development of an allergic reaction. The mechanism of development of an allergic reaction of an immediate type (type I, immediate type hypersensitivity (ITH), atopic type, reaginic type, IgE-mediated type, anaphylactic type)
Allergy is understood as the acquired ability of the body to specifically respond to various foreign substances from the external environment or to its own altered macromolecular substances or cells.
In principle, an allergic reaction carries elements of a protective mechanism, since it determines the localization of bacterial allergens that have entered the body. In serum sickness, the formation of immune complexes promotes the removal of antigen from the blood. But in any case, allergic reactions entail damage to their own tissues, which can lead to the development of allergic diseases. The question of which reaction (immune or allergic) will develop in an individual depends on a number of conditions and circumstances. Usually, weak antigens in large quantities or repeatedly entering a weakened body often cause allergic reactions.
Allergic reactions are based on the combination of Ag (allergen) with AT or sensitized lymphocytes. In addition to IgE, IgM and IgG, antibody-dependent and natural killers, T-killers, neutrophils, monocytes, eosinophils, basophils, mast cells, CEC, various mediators and biologically active substances (prostaglandins, thromboxanes, leukotrienes, etc.) ).
The most important component in the deployment of immediate allergic reactions is histamine. Its main sources are mast cells And blood basophils.
Histamine acts on two types of cell receptors - H1 and H2. Through H1, it causes contraction of smooth muscles of blood vessels, bronchioles, bronchi, gastrointestinal tract, increases vascular permeability, causes itching, vasodilatation of the skin. Through H2, it increases the permeability of the walls of blood vessels, the production of mucus in the bronchi, and expands the bronchioles.
5.1. CLASSIFICATION OF ALLERGENS
An allergen is an Ag or hapten that causes an allergy, usually does not damage the tissues of a healthy person with no allergy.
There are several classifications of allergens.
Exoallergens live in the human environment and are divided into the following: fig. 4 and 5.
Rice. 4. Ecological classification of allergens (B.N. Rayskis et al.)
Rice. 5. Classification of allergens by origin (B.N. Rayskis et al.)
5.2. CLASSIFICATION OF ALLERGIC REACTIONS
The old names of allergic reactions of immediate and delayed types (GNT and HRT) do not reflect the biological essence of the phenomenon, although they continue to be retained. Cutaneous HNT (PCNT) occurs with secondary intradermal administration of Ag after 10-15 minutes, with HRT
(PCHZT) - after 10-21-48-72 hours.
According to the classification of Coombs and Gell, allergic reactions are divided into 4 types.
Type 1. It is caused by the formation of cytotropic antibodies, primarily of the IgE class (reagins), which are fixed on mast cells, basophils, and bind to allergens circulating in the blood. There is an immune complex reagin-allergen. The formation of such a complex on the cell membrane causes degranulation of mast cells due to a change in their membranes and the release of granules containing histamine, serotonin, acetylcholine, the "slow-reacting substance of allergy." These substances provoke spasm of smooth muscles, increase capillary permeability and other effects.
Type 1 reactions are divided into early And later. The most important are later. They usually develop after 3 hours and last up to 12-24 hours. Often, in patients with bronchial asthma, double reactions are induced in response to the introduction of house dust allergen. (early And later) reactions. Late response enhances hypersensitivity to non-allergic (non-specific) stimuli - cold, stress.
Type II.Cytotoxic hypersensitivity. The reaction occurs when AT interacts with Ag or hapten, which is associated with the cell surface and can be a drug. Complement, killer cells (K-cells) take part in the reaction. As AT can be IgM, IgG. To induce a type II reaction, it is necessary for the cell to acquire autoallergenic properties, for example, when it is damaged by drugs, bacterial enzymes, and viruses. The resulting antibodies activate complement. Some cells take part in the reaction, for example, T-lymphocytes carrying the Fc fragment. There are three mechanisms of target cell lysis: a) due to complement, occurring with the participation of activated complement, which causes perforation of membranes and the release of proteins and other cellular substances; b) intracellular cytolysis of opsonized Ag inside a macrophage under the influence of lysosomal enzymes; c) AT-dependent
Simaya cellular cytotoxicity caused by K-cells with the participation of IgG.
The cytotoxic type of reaction plays an important role in immunity in protecting the human body from bacteria, viruses, and tumor cells. If healthy human cells, under the influence of external adverse factors, become Ag, the reaction from a protective one turns into a damaging one - an allergic one. An example of a pathology that occurs according to this type of reaction can be hemolytic anemia, lymphocytopenia, platelet purpura, etc.
Type III. Got a name immune complex damage reactions and the Arthus phenomenon. In the blood of patients, there is a large excess of Ag-AT complexes, which fix and activate the C3 component of the complement. The reaction develops according to the scheme: IgG - immune complexes - complement. Usually, the reaction is induced 2-4 hours after the encounter with Ag, reaches a maximum after 6-8 hours, and can last for several days. The negative charge of immune complexes is important; positively charged immune complexes are quickly deposited, for example, in the renal glomeruli, while neutral ones penetrate them very slowly, because glomeruli have a negative charge. Pathological damage to cells often occurs where immune complexes are retained - in the kidneys (glomerulonephritis), lungs (alveolitis), skin (dermatitis). By type III allergic reactions also develop serum sickness, exogenous allergic alveolitis, drug and food allergies, exudative erythema multiforme, autoallergic diseases (rheumatoid arthritis, systemic lupus erythematosus), glomerulonephritis, periarteritis nodosa. With severe complement activation, even some clinical and pathogenetic variants of anaphylactic shock can be observed.
Type IV- delayed hypersensitivity (DTH) or cell-mediated immune responses. Ag with this type of allergy can be microbes, protozoa, fungi and their spores, drugs, chemicals. Ingestion of antigen into the body causes sensitization of T-lymphocytes. Upon repeated contact with Ag, they release more than 30 different mediators that act on various blood cells and tissues through the corresponding receptors.
By type of allergic cellular reactions IV type a number of diseases occur - infectious allergies (bronchial asthma and allergic rhinitis), mycoses, some viral infections (measles,
mumps). A classic example of a reaction IV type may be allergic contact dermatitis (Ag - a chemical) and a reaction to tuberculin in patients with a corresponding infection. This also includes dermatitis (eczema) caused by haptens, rejection of transplanted tissues and organs.
For types allergic reactions, the formation of antibodies is crucial, so they were combined under the name humoral allergic reactions(old name - GNT). IV type is a purely cellular phenomenon (CTH). In reality, several types of reactions often develop simultaneously. For example, mechanisms of types I and III are involved in anaphylaxis, II and IV in autoimmune diseases, and all four in drug allergies.
Immune responses have also been identified V type. They are caused by IgG directed against cell receptors, cause either stimulation of their function, for example, thyroglobulin, or blocking the formation of insulin, etc.
5.3. ATOPIC DISEASE
Term "atopy" was introduced in 1923 to emphasize the difference between atopic disease and the phenomenon of anaphylaxis. The group of classical atopic diseases includes year-round atopic rhinitis, hay fever, atopic form of bronchial asthma and atopic dermatitis. Closely associated with this group of diseases are certain acute allergic reactions to drugs and food.
The most important sign of atopy is hereditary predisposition. If one parent suffers from atopy, the pathology is transmitted to children in 50%, if both - in 75%.
Atopy is accompanied by certain immune disorders.
1. Increased ability of the immune system to respond with the formation of IgE to weak antigenic stimuli, to which people who do not suffer from atopy either do not respond at all or form antibodies of other classes of immune globulins. In the blood with atopy, the concentration of total and specific IgE is sharply increased.
2. There are violations of the function of lymphocytes in the form of a decrease in the number of CD3 + , CD8 + , a proliferative response to antigen and PHA, suppressive activity of NK, skin reactions to contact allergens, to intradermal administration of tuberculin, candidin, IL-2 production. At the same time, there is an increase in the content of CD4 + cells, hyperreactivity of B-lymphocytes to Ag and
B-mitogens, histamine binding by B-lymphocytes in the period of exacerbation of the disease.
3. Chemotaxis of monocytes and neutrophils is inhibited, which reduces the efficiency of phagocytosis, inhibits monocyte-lymphocyte cooperation and antibody-dependent monocyte-mediated cytotoxicity.
In addition to the listed immune disorders, atopy is characterized by the inclusion of a number of non-specific pathogenetic mechanisms:
1. Disbalance of sympathetic and parasympathetic innervation of body systems
In all three classic atopic diseases, cholinergic α-adrenergic reactivity is increased with a decrease in β-2-adrenergic reactivity.
2. There is an increased ability of mast cells and basophils to release mediators both spontaneously and in response to non-immune stimuli.
3. Atopic diseases are accompanied by varying degrees of eosinophilia and infiltration of mucous membranes and secretions of the respiratory tract and gastrointestinal tract.
Thus, immune and non-immune mechanisms are involved in the implementation of atopic reactions, according to this V.I. Pytsky (1997) identifies three options:
With a predominance of specific mechanisms;
The middle variety, where specific and non-specific reactions are expressed;
With a predominance of non-specific mechanisms - a pseudo-allergic variant of atopic disease.
Thus, the concept of atopy not equivalent the concept of allergy. Atopy is a broader phenomenon than allergy. Atopy can occur with allergies, when immune mechanisms are activated, and without it, when there are no immune mechanisms or they are minimal and do not play a leading role.
Allergic reactions are divided into true And pseudoallergic. The first one is based on three mechanisms. First- immune, due to the interaction of antibodies (sensitized cells) with the allergen. Second- pathochemical, in which the release of the corresponding mediators occurs. Third- phenomenological, which is characterized by the manifestation of a symptom of the disease.
In case of pseudo-allergic reactions (PAR), the immunological stage is absent, while the remaining stages appear, but the symptoms of the disease develop in an accelerated way.
The reasons for the development of PAR are as follows.
1. The intake of excess histamine in the body with food (cheese, chocolate, potatoes).
2. The appearance in the body of liberators of its own histamine from the corresponding cells (fish).
3. Violations of histamine inactivation in the body (oxidation by diamine oxidase, monoamine oxidase, methylation of nitrogen in the ring, methylation and acetylation of the amino group of the side chain, binding by glycoproteins).
4. Intestinal diseases leading to disorders of absorption processes, creating conditions for the absorption of large molecular compounds that have the properties of allergens and the ability to cause non-specific reactions of allergy target cells. Sometimes these factors are mucoproteins that bind histamine, protecting it from destruction.
5. Insufficiency of the hepato-biliary system - a violation of histamine degradation in liver cirrhosis, cholecystitis, cholangitis.
6. Dysbacteriosis, in which excessive formation of histamine-like substances and their increased absorption are possible.
7. Activation of the complement system, leading to the formation of intermediate products (C3a, C2b, C4a, C5a, etc.), which are capable of causing the liberation of mediators from mast cells, basophils, neutrophils and platelets.
Often, PAR occurs after the administration of medications and ingestion of food.
Particularly severe reactions occur with parenteral administration of drugs, the introduction of local anesthetics during tooth extraction, during X-ray contrast studies, instrumental examinations (bronchoscopy), and physiotherapy procedures (inhalations, electrophoresis).
Clinical manifestations of PAR are diverse: from local (contact dermatitis) to systemic (anaphylactic shock). In terms of severity, PAR can be light And heavy up to death.
PAR occur more often in women over 40 years of age with concomitant diseases of the gastrointestinal tract, liver, and neuroendocrine system.
Often there is simultaneous intolerance to several drugs from different chemical groups.
As a rule, PAR is accompanied by a decrease in phagocytosis, a decrease in the level or imbalance of individual subpopulations of lymphocytes, which contributes to the chronicity of concomitant foci of infection, disruption of physiological processes in the gastrointestinal tract, liver, etc.
5.4. PRINCIPLES OF DIAGNOSTICS OF ALLERGIC DISEASES
In the process of diagnosis, it is necessary to determine whether the disease is allergic, and to establish the nature of the acting allergen and the mechanism of the developed reaction. Therefore, at the first stage, in essence, it is necessary to differentiate exogenous allergies from autoimmune and infectious diseases, which may also be based on hyperergic mechanisms. At the second stage, when the allergic nature of the disease is established, its connection with a certain allergen and the type of allergy are clarified. In parallel, a distinction is made between allergic and pseudo-allergic reactions.
Diagnosis of allergic diseases, as a rule, is carried out in a complex manner in a certain sequence, when some methods of analysis follow others (see Fig. 6).
Allergological history
When collecting an anamnesis, a patient's hereditary disposition and previous allergic diseases, atypical reactions to food, medicines, insect bites, etc. are revealed; connection of pathology with climate, season, day, physical factors (cooling, overheating); place of development of an attack of the disease, etc .; influence of household factors; connection of exacerbations with other diseases, the postpartum period, with vaccinations; influence of working conditions (presence of occupational hazards); the dependence of the disease on the intake of medicines, food products; the possibility of improving the condition in the elimination of allergens during vacations, business trips.
Rice. 6. General principles for diagnosing allergic diseases
Clinical laboratory tests
- Indirect degranulation of basophils (Shelly test)
The reaction is based on the ability of the Ag-AT complex to cause degranulation of basophils. A positive test reveals hypersensitivity to the allergen, a negative result does not rule it out. - Reaction of degranulation of mast cells The interpretation of the reaction is the same as in the previous case.
- Reaction of blast transformation of lymphocytes (RBTL)
Its essence lies in the ability of sensitized lymphocytes to enter into a blast transformation reaction in the presence of a causative allergen.
- Leukocyte migration inhibition reaction (RTML) Sensitized leukocytes upon contact with the causative
allergen inhibit their mobility.
- Neutrophil Damage Index (NDI)
An allergen causes damage to the corresponding cells in the presence of allergization to it.
Skin tests
Specific allergen tests are an objective method for diagnosing allergic conditions. The morphology of a positive skin test makes it possible to judge the type of allergy. Immediate reactions characterized by the appearance of a pink or pale blister with a peripheral zone of hyperemia. For reactions III and IV types redness, swelling, infiltration of the focus of inflammation are characteristic. Positive skin tests indicate the presence of sensitization to this allergen, which, however, does not indicate its clinical manifestation.
Several variants of skin tests are used: drip, skin, scarification, injection, intradermal. They are implemented on the inner surface of the forearm, less often on the back or thigh.
Provocative tests
- thrombopenic test
A decrease in the number of platelets after contact with the allergen is determined by more than 20%.
- Leukopenic test
A similar decrease in the number of leukocytes is determined.
- Nasal provocation test
The appearance in the nostril after instillation of the allergen of congestion, as well as sneezing, runny nose.
- conjunctive provocation test
The appearance in the conjunctiva of the eye after the introduction of the allergen itching, swelling, redness of the eyelids.
- Leukocyte natural migration inhibition test Detects a decrease in the number of leukocytes in the liquid after rinsing the mouth in the presence of allergens.
- Sublingual Test
It is considered positive after placing under the tongue 1/8 tablet of the drug or part of the therapeutic dose of the liquid drug.
- Gastrointestinal provocation test
Provocation of relevant disorders after ingestion of the causative food allergen.
5.5. PRINCIPLES OF TREATMENT OF ALLERGIC DISEASES
Traditionally, there are 6 basic principles for the treatment of allergic diseases:
Elimination of the allergen from the patient's body;
The use of agents that non-specifically suppress allergic reactions without taking into account the characteristics of the allergen;
Non-drug treatments for allergies;
immunosuppressive therapy;
Specific desensitization or specific immunotherapy;
Targeted immunocorrection.
In practice, any one principle of treatment is rarely used, their combinations are used. Therapy is also implemented using symptomatic agents, the choice of which depends on the clinical manifestation of the disease and the patient's condition. For example, with bronchospasm, drugs that dilate the bronchi are used.
Tactics of treatment of patients significantly depends on the stage of the disease. Yes, in period of exacerbation therapy is aimed primarily at eliminating the acute clinical manifestations of an allergic reaction, at preventing its progression. IN remission period the main task is to prevent relapse by changing the reactivity of the body.
Elimination of allergens
At food allergies products that cause pathological reactions are excluded from the diet, with medical- medicines, domestic remove upholstered furniture, pillows, fur products, pets. They carry out wet cleaning of the premises, carry out the fight against insects (cockroaches), it is recommended to leave the place of flowering plants, stay in air-conditioned wards.
In cases where patients have already formed an allergic reaction to the necessary drug, the drug is administered fractionally in small concentrations until the required therapeutic dose is reached.
Means of non-specific allergy therapy
For the treatment of allergic diseases, methods are used that inhibit the immune, pathochemical and pathophysiological (phenomenological) stages of reactions. Many of them are simultaneously
but act on several mechanisms for the deployment of allergic reactions.
Antimediator drugs. Currently, about 150 anti-mediator drugs are produced in the world. The general mechanism of their functioning is associated with a high affinity of these drugs for histamine receptors of cells in various organs. Basically, they block histamine H1 receptors in the “shock” organ, resulting in cell insensitivity to mediators of allergic inflammation. Other ways to achieve an antimediator action are blocking histamine by inhibiting histidine decarboxylase, immunizing the patient with histamine or histoglobulin to induce antihistamine antibodies, or administering ready-made monoclonal antibodies.
The method of administration of antihistamines depends on the severity of the course and phase of the disease. Drugs are usually administered orally, subcutaneously, intravenously or topically in the form of solutions, powders, ointments. All of them pass through the blood-brain barrier and therefore cause sedation due to the binding of H1 receptors in the brain. They are prescribed, as a rule, 2-3 times a day, the duration of treatment should not exceed 15 days, it is recommended to change the drugs every week of admission.
There are 6 groups of antihistamine compounds that block H1 receptors:
- Ethylenediamines.Chloropyramine.
- Ethanolamines.Diphenhydramine.
- Alkylamines.Dimetindene (Fenistil).
- Derivatives of phenothiazine.Diprazine.
- piperazine derivatives,cinnarizine.
- Antihistamines of various origins,clemastine, hifenadine, bicarfen, cyproheptadine, mebhydrolin, ketotifen (zaditen). Increasingly widespread are H1 - antihistamines of the 2nd generation, which include loratadine, claritin, hismanal, zyrtec, semprex and etc.
In 1982, non-sedating terfenadine, a blocker of H1-histamine receptors, was created. However, in rare cases, it has contributed to the development of serious cardiac arrhythmias. Its active metabolite is fexofenadine hydrochloride. (fexofenadine) is a highly active and highly selective blocker of H1-histamine receptors, does not have a cardiotoxic effect, does not pass through the hemato-
encephalic barrier, does not show a sedative effect, regardless of the dose.
H2 receptor blockers include cimetidine.
There are general application rules antihistamines.
In case of skin diseases, exclude topical use of drugs due to the possibility of histamine release from cells.
Do not prescribe drugs of the phenothiazine group for photodermatosis and hypotension.
For breastfeeding mothers, prescribe only small doses of drugs so as not to cause drowsiness in the child.
Do not use drugs with strong sedative properties in patients with asthenodepressive condition.
To determine effective drugs, an individual choice is recommended.
With prolonged use, it is necessary to replace one drug with another every 10-14 days in order to avoid addiction and complications.
If H1 blockers are ineffective, they should be combined with antihistamines directed against H2 receptors and other antimediator drugs.
Pharmacological and side effects of antihistamines
Sedative and hypnotic action.
Inhibition of the function of the endocrine system, an increase in the viscosity of secrets.
Local anesthetic and antispasmodic action.
Strengthening the effects of catecholamines and depressants (anesthetics, analgesics).
Since many mediators are involved in the deployment of allergic reactions, the possibilities of non-specific treatment are expanded by exposing them to a number of drugs:
Antiserotonin agents- cinnarizine, sandostene, peritol, deseryl.
kinin system inhibitors(due to the blockade of the formation of vasoactive polypeptides) - contrical, trasilol, ε-aminocaproic acid.
Inhibitors of the kallikrein-kinin system conditionally divided into three groups:
1. Drugs with anti-bradykinin action - anginin, prodectin, parmidin, glivenol.
2. Antienzymatic drugs that inhibit the activity of blood proteases - trypsin, contrical, trasilol, tzalol, Gordox.
3. Drugs affecting the kallikrein-kinin system through the coagulation and fibrinolysis system - ε-aminocaproic acid (EACA).
Complement system inhibitors - heparin, suramin, chlorpromazines (chlorpromazine).
Heparin It has anti-inflammatory, anticoagulant, immunosuppressive, anti-complementary, anti-mediator effects through its influence on factor XII (Hageman) of the blood coagulation system. Actively implements the action on various parts of the immune system.
Suramin 76% causes suppression of the complement system. Chlorpromazine inhibits and inhibits the formation of C2 and C4 complement components.
Medicines endowed anticholinergic activity - ipratropium bromide.
Antagonists of the slow responding system - diethylcarbamazine.
Histamine used for "training" and stimulation of H2 receptors. Usually, the drug is administered subcutaneously, starting with a dose of 0.1 ml of a dilution of 10 -7 M, adding 0.1 ml with each injection.
Group cromoglycic acid is a membrane stabilizer, prevents the release of histamine and slow-reacting substances, prevents the expansion of calcium channels in target cells, the ingress of calcium into them and spasm of smooth muscles.
Widely used in the treatment of allergic diseases histaglobulin, consisting of histamine and γ-globulin. When it is administered, antihistamine antibodies are formed in the body that bind free histamine circulating in the blood. The effect occurs within 15-20 minutes after administration.
Quite active anti-mediator drug - histoseratoglobulin, acting on many mediators of an immediate allergic reaction.
calcium channel antagonists(nifedipine, verapamil) reduce mucus secretion and reduce bronchial hyperreactivity.
In case of lysis of blood cells and the formation of granulocytopenia (type II allergy) shown quercetin, tocopherol acetate, lithium carbonate, phagocytic immunity stimulants(sodium nucleinate,
lev and mizol, thymus preparations, diucifon, to some extent - pyrimidine derivatives). Means that enhance the detoxifying capabilities of the liver (katergen), successfully used in patients with the formation of pathological immune complexes (type III allergy).
Appointment of immunomodulators - sodium nucleinate, myelopida, levamisole and other means of this series is quite effective. They increase the number and function of CD8 + cells, which inhibit the formation and function of CD4 + lymphocytes and T-killers, which are known to trigger the manifestation of all types of allergies.
Calcium preparations have not lost their significance in the treatment of allergic diseases (serum sickness, urticaria, angioedema, hay fever), as well as in situations of drug allergy formation, although the mechanism of this effect has not been fully elucidated. Usually calcium chloride and calcium gluconate are used.
Non-drug methods of non-specific treatment of allergies
Hemosorption and immunosorption is the method of choice for the treatment of severe forms of allergies with polysensitization, when specific treatment is not possible. Contraindications for hemosorption are: pregnancy, chronic foci of infection in the acute stage, severe diseases of internal organs with impaired function, blood diseases and a tendency to thrombosis, peptic ulcer of the stomach and duodenum in the acute stage, status asthmaticus with hypertension.
Plasmapheresis and lymphocytopheresis based on the use of gravitational blood surgery. Plasmapheresis is based on the removal from the body after preliminary plasma separation of pathological proteins and other elements.
Extracorporeal immunosorption is a new direction of extracorporeal therapy. Substances capable of interacting with the pathogenic component of plasma are fixed on the sorbent. Sorbents are divided into selective, capable of removing harmful products in a non-immunochemical way (heparin-agarose sorbent), and specific, which act according to the Ag-AT reaction type. Selective plasmapheresis allows you to remove circulating from the blood of patients.
Immunosuppressive therapy
This method of treatment includes primarily the use of glucocorticosteroids. Information about the drugs of this series is already
cited earlier. Recall that their ability to suppress the local inflammatory response, reduce exudation and proliferation, reduce the permeability of capillaries, serous membranes, inhibit the proliferation of leukocytes and the secretion of mediators leads to the suppression of various phases of immune and allergic reactions with a high therapeutic effect.
With the ineffectiveness of the use of drugs of this group, the use of cytostatics is theoretically substantiated, especially in the formation of type IV allergies in patients. Sometimes cytostatics are combined with hormones to reduce the therapeutic doses of the latter. The rate of onset of the clinical effect is fast when using glucocorticosteroids and slower when using cytostatics. The side effects of such interventions are numerous, which is why their administration is sometimes referred to as desperation therapy. And this is not surprising, since after taking even small doses cyclophosphamide immune system disorders persist for several years.
Specific hyposensitization (specific immunotherapy, SIT)
This type of treatment is usually carried out in cases where traditional (non-specific) treatments have proven ineffective. The essence of this approach lies in the fact that patients are injected with a causative allergen to produce antibodies, starting with small, then medium and large doses that block the process of binding of allergens to reagins and suppress the formation of the latter. Water-salt extracts of allergens are used as immunizing agents. allergoids- allergens chemically modified with formaldehyde or glutaraldehyde.
The introduction of allergens in specific immunotherapy includes subcutaneous, oral, intranasal, inhalation, and other routes. There are pre-season, year-round, intra-season SIT. Apply classical a method of introducing allergens, in which injections of allergens are made 1-3 times a week, and accelerated, at which 2-3 injections are made per day. In the latter case, the patient receives a course dose of the allergen in 10-14 days. To reduce the risk of complications, patients need to additionally administer antihistamines. At the same time, this reduces the effectiveness of the body's immune response.
A variant of SIT is autoserotherapy. The essence of the method lies in the fact that the patient is injected intradermally with serum obtained on
the peak of the exacerbation of the disease. It is believed that with such exposure, conditions are created for the formation of an anti-idiotypic response.
Close to this was the treatment of patients with autolympholizat. D.K. Novikov (1991) believes that in the stage of exacerbation of an allergic disease, the number of sensitized lymphocytes increases and autoimmunization of patients by them causes the formation of autoantibodies that inhibit hypersensitivity and causes desensitization.
The following assessment of the effectiveness of the ME was adopted:
4 points- after treatment, all manifestations of the disease disappear.
3 points- exacerbations of the pathological process become rare, mild and effortlessly stopped by medications.
2 points- achieving a satisfactory result, i.e. the symptoms of the disease remain, but their severity is reduced, the number of necessary medicines is reduced by about half.
1 point- an unsatisfactory result, in which there was no improvement in the clinical condition of patients.
Specific treatment is performed after establishing the initial dose of the causative allergen using allergometric titration. To do this, patients are injected with 0.1 ml of the allergen at a dilution of 10 -7 to 10 -5, followed by taking into account the skin reaction. At the same time, the patient is injected with a solution in which the allergen is diluted, and a 0.01% solution of histamine (controls). For the therapeutic dose of allergens take the maximum dilution, giving a negative skin reaction.
Contraindications for specific hyposensitization are:
The period of acute exacerbation of the underlying disease and pronounced changes in the shock organ - emphysema, bronchiectasis;
The presence of an active tuberculosis process;
Diseases of the liver, kidneys, collagenoses and other autoimmune processes;
Carrying out preventive vaccinations.
Rules for specific immunotherapy
Injections, as a rule, are not done during menstruation, they are not combined with other methods of treatment that complicate or reduce the effectiveness of SIT. After the introduction of the allergen, patients are under the supervision of a doctor or nurse for 15-20 minutes.
ry. There should be an anti-shock kit in the treatment room, because. anaphylactic reactions are possible. In the event of a local reaction (redness, itching, swelling of the skin), a one-day break is taken and the injection of the dose that preceded the formation of an allergic reaction is repeated. Similarly, they act in cases of development of general reactions (appearance of itching, sore throat, bronchospasm, wheezing in the lungs). If necessary, stop the introduction of the allergen for 1-3 days and prescribe antihistamines and other drugs (sympathomimetics, aminophylline). For highly sensitized patients, inhalation can be used cromoglycic acid (intala) or inject its solutions into the nose. Treatment is interrupted when significant allergic reactions, acute non-allergic diseases or chronic exacerbations appear. After a break of 7-10 days, specific immunotherapy is usually carried out first.
Complications of SIT
Usually, with injections of allergens, local reactions occur in 12-75%, general - in 9-50% of cases. Their appearance indicates either an excess of the dose of the injected allergen, or an incorrect scheme for its administration.
The most serious manifestation of allergic reactions is anaphylactic shock, requiring emergency and intensive care. Therefore, we will dwell on this issue in more detail.
Targeted immunocorrection
Since allergic reactions almost always develop with suppression of the T-suppressor link of immunity, drugs should be prescribed that increase the number or potentiate the activity of the corresponding subpopulation of T-lymphocytes (decaris, thymic preparations, sodium nucleinate, licopid).
5.6. SOME CLINICAL FORMS OF ALLERGY
Anaphylactic shock
This is an acute generalized non-specific reaction to various chemical, biological substances and physical factors that induce the formation and release of mediators of immediate hypersensitivity, causing characteristic clinical symptoms. There are several variants of anaphylactic shock.
Hemodynamic - the prevalence of symptoms of disorders of the cardiovascular system.
Anaphylactic - in which the leading is acute respiratory failure.
Cerebral- when changes in the central nervous system prevail (loss of consciousness, psychomotor agitation).
Abdominal - characterized by a picture of "acute abdomen" with pain and symptoms of peritoneal irritation, with possible perforations and intestinal obstruction.
Cardiogenic - in which there is an imitation of acute myocardial infarction with pain in the heart and acute coronary insufficiency.
Treatment activities include the following:
1. Stopping the intake of the allergen into the body, for this purpose, the injection site of the allergen is cut with 0.3-1 ml of a 0.1% solution of epinephrine (adrenaline).
2. Enter intramuscularly or subcutaneously, or sublingually 0.2-0.5 ml of a 0.1% solution of epinephrine in a total dose of up to 2 ml every 10-15 minutes until a therapeutic effect is achieved.
3. At the same time, intravenous bolus, then drip infusion of glucocorticosteroids up to 60-90 mg with a daily dose of up to 160-1200 mg in saline or 5% glucose solution.
4. In the absence of an effect in a serious condition, intravenous drip administration of 0.2-1.0 ml of 0.2% norepinephrine (norepinephrine) or 0.5-2 ml of 1% phenylephrine (mezaton) in 400 ml of 5% glucose solution per isotonic sodium chloride solution.
5. With bronchospasm, up to 10 ml of 2.4% aminophylline in saline can be administered intravenously.
6. Antihistamines of two different groups can be injected intramuscularly - 1-2 ml of 2% suprastin, 2-4 ml of 0.1% clemastine, up to 5 ml of 1% diphenhydramine.
7. With the development of acute left ventricular failure, 0.3-0.5 ml of a 0.05% solution of strophanthin-K in saline is used, as well as 20-40 mg of furosemide.
8. Respiratory analeptics are shown - nikethamide - 2 ml, caffeine 10% - 2 ml, etimizole 1.5% 2-3 ml subcutaneously, intramuscularly, 2-4 ml of diazepam or 2-4 ml of relanium.
9. In case of cardiac arrest, 0.5 mg 0.1% is injected intravenously
epinephrine in 100 ml of 4% sodium bicarbonate solution, intracardiac (in the IV intercostal space 2 cm outward from the left edge of the sternum - 0.5 ml of 0.1% epinephrine, 10 ml of 10% calcium gluconate).
drug allergy
Drug intolerance is one of the most important problems of modern medicine. This condition is found in 3.9% of those examined for allergic diseases. The term drug intolerance includes specific(true allergic) And non-specific(pseudo-allergic) reactions to medications, as well as complications of drug therapy. The latter include intoxication with the development of toxicoderma, absolute and relative overdose, cumulation of drugs, side effects, individual intolerance, secondary effects, polypharmacy.
Unwanted allergic reactions to medications account for 15 to 60% of all home visits. Drug allergy is an increased specific immune response to drugs, accompanied by general and local clinical manifestations. The most common cause of complications are antibiotics (26%), and among them penicillin (59.7%), vaccines and serums (22.8%), analgesics, sulfonamides and salicylates (10%).
Routes of administration of drugs affect the degree of their allergenicity. Penicillin, for example, is the most allergenic when applied (5-12%), dermal and inhalation (15%) administration, the least - when parenteral. The simultaneous use of many drugs creates conditions for the interaction of not only the initial substances, but also their metabolites, during which highly allergenic complexes and conjugates can occur. Often medications cause cross-allergic reactions.
Basically, any the drug may cause allergic or pseudo-allergic reactions.
drug anaphylactic shock can be induced by various drugs, most often antibiotics.
Stevenson-Johnson Syndrome - malignant exudative erythema, acute mucocutaneous ocular syndrome, induced by sulfonamides, antipyretics, antibiotics. Characterized by rapid onset, high fever, sore throat,
joints, herpetic eruptions (erythematous, papular and vesiculo-bullous). Erosions on the mucous membranes quickly form. There are stomatitis, uveitis, vulvovaginitis, conjunctiva of the eyes.
Lyell's syndrome - toxic epidermal necrosis (scorched skin syndrome). Mortality reaches 30-50%. People of all ages suffer. The disease begins 10-21 days after taking the medication (antibiotics, sulfonamides, salicylates, barbiturates, etc.). The onset is sudden - chills, vomiting, diarrhea, fever, painful burning of the skin, a rash in the form of erythematous edematous painful spots, the formation of thin-walled blisters, erosions. The oral cavity and tongue are a continuous wound surface. Symptoms of meningoencephalitis, glomerulonephritis, hepatitis appear, abscesses of the brain and spleen form, and cardiovascular insufficiency increases.
There are localized forms of drug allergy, which are in the form of skin rashes (small-spotted, roseolous, maculopapular). Erythema may form in the form of large hyperemic spots. Sometimes exudative erythema multiforme is formed in the form of an acute skin lesion with the formation of spots, nodules, blisters. Allergic rhinitis is more often observed in workers of pharmacies and the pharmaceutical industry. Allergic pharyngitis, laryngitis, tracheitis, as a rule, appear when the patient comes into contact with aerosols. Possible liver damage when using sulfonamides, erythromycin, indomethacin, salicylates, nitrofurans, penicillin. Glomerulonephritis is often induced by antibiotics, gold salts, novocaine, sulfonamides, etc.
Treatment of drug allergies
Treatment begins with the abolition of all previously used drugs, except for vital ones.
Very often in patients with medicinal observed and food allergy. Therefore, they need to prescribe a hypoallergic diet with carbohydrate restriction, the exclusion of foods with extreme taste sensations (salty, sour, spices, etc.).
With mild manifestations of allergies, it is sufficient to cancel the medication and prescribe parenteral administration of antihistamines or any other antimediators. In the absence of a positive effect of treatment, corticosteroids are used in doses (in terms of prednisolone) from 60 to 120 mg.
With moderate severity of allergic lesions, hormones are used repeatedly during the day, but not less than after 6 hours. When a lasting effect is achieved, they are canceled. In other cases, the dose of these drugs has to be increased.
With the formation of various complications from the internal organs, syndromic therapy is indicated.
An allergy is an increased sensitivity of the body to the effects of certain environmental factors.
Allergy often manifests itself during the flowering of herbs, in contact with pets or inhalation of dye fumes. An allergic reaction can be caused by drugs and even ordinary dust.
In some cases, certain foods, synthetic compounds, chemical detergents, cosmetics, etc. are intolerable.
Allergy due to environmental pollution becomes especially dangerous. More and more people are suffering from it.
Allergy its causes and symptoms
The main signs of allergies:
skin redness,
Inflammation of the mucous membranes - the appearance of a runny nose and tears,
Attacks of coughing.
Sometimes the rhythm of the heartbeat can be disturbed and a general malaise develops. And edema of the larynx, lungs are life-threatening. Anaphylactic shock caused by allergies can also be fatal.
The main factor on which the manifestation of an allergic reaction depends is the immune system. The immune system is designed to protect the body from elements that can have a harmful effect on it. The danger can come from microbes, foreign proteins, various chemicals, and even from the body's own cells if they tend to degenerate into malignant cells that develop into cancerous tumors.
antigens called elements that interfere with the normal functioning of the body, carrying a certain danger to its existence. These can be various enzymes, toxins, foreign proteins and other substances that enter the body with microbes, plant pollen, drugs, in particular sera. Antigens are counteracted by special blood proteins - antibodies, otherwise called immunoglobulins . They are produced by some cells of the lymphatic system in the presence of antigens.
Immunoglobulins are highly sensitive to the presence of foreign substances. They are designed to bind and block antigen cells. And subsequently, together with them, they are destroyed by special cells (phagocytes) and excreted from the body.
In the process of interaction of antigens and antibodies, substances that have a negative effect on the body can be produced. They play an important role in the occurrence of allergic reactions.
The body usually secretes the necessary amount of antibodies to fight antigens. But if for some reason the immune system malfunctions and produces more than necessary, the number of immunoglobulins, the latter can have a destructive effect on the body, causing allergic reactions that are dangerous to health and even to life itself. An inadequate response of the body to exposure to foreign substances is an allergy.
Certain types of antibodies oppose various antigens. There are total five classes of immunoglobulins, each of which must protect the body from certain antigens.
Class A - immunoglobulins that counteract various harmful microbes, toxins, viruses and protect mainly the mucous membranes. This type of antibody also includes those that play an important role in the body's reaction to cold and in protection against certain allergens. Class A immunoglobulins are involved in the mechanism of occurrence of rheumatic allergic diseases.
Class D represented by immunoglobulins released during inflammation of the bone marrow, i.e. osteomyelitis, and involved in a number of skin allergic reactions.
Class G are the most commonly used immunoglobulins. Within this group, there are several varieties of antibodies designed to combat certain types of toxins, microbes and viruses. But the immunoglobulins themselves of this class can cause a number of severe allergic diseases. In particular, hemolytic disease of infants (developing as a result of the production of antibodies in the mother's blood against the Rh factor present in the blood of the fetus), neurodermatitis, eczema and some others.
Class E - the most active in the development of allergies immunoglobulins. They are the first to react to the appearance of allergens, although they are not directly involved in their destruction. They also contribute to the formation of a special allergic mood of the immune system. The content of antibodies of this type in the body depends, in particular, on age - the largest number is produced by 7-14 years of age.
The presence of a more or less significant proportion of class E immunoglobulins also varies depending on the geographical location and climatic conditions of the country in which the person lives.
Class M another immunoglobulin. These antibodies are involved in the fight against intestinal infections and rheumatic diseases. They bind bacteria that enter the body; destroy red blood cells of incompatible blood groups.
Among themselves, the immunoglobulins of the five classes mentioned differ not only in their role in resisting antigens, but also in molecular weight and specific proportion in the total number of antibodies.
Involved in the process of recognition and destruction of foreign cells are various cells of the immune system, which are scattered throughout the body. They are called lymphocytes and are formed through the transformation of stem cells.
The task of recognizing antigens is assigned to those cells that first come into contact with foreign elements. This macrophages and monocytes , as well as some cells of the liver and nervous system. Then antigens are opposed lymphocytes. They, in turn, are divided into several categories depending on the functions performed. Part of the lymphocytes is involved in blocking foreign elements, part - in the production of the necessary antibodies.
Cytokines- Substances secreted by lymphocytes contribute to the activation of antigen-destroying cells, play an important role in the destruction of dangerous tumors formed in the body. In the case of a clear work of the immune system, they are also eliminated in the future. But, if the body is prone to an inadequate reaction, an excessive amount of these biologically active substances is produced. And not all cytokines are destroyed after getting rid of antigens. Some of them oppose completely healthy cells of their own body, cause inflammation, and begin to destroy organs. This is the mechanism for the development of an allergic reaction. It should be noted that the release of histamine and a number of other chemical substances that are characterized by increased activity by interacting cells is of particular importance.
It is in cases where the immune system is overly sensitive to the effects of antigens on the body that allergic reactions occur.
Pseudo-allergy and true allergy: how do they differ
In addition to the described true allergy, the so-called pseudo-allergy or false allergy is known. true allergy manifested as a result of a malfunction of the immune system. Origin mechanism pseudo-allergies different. The latter differs from a true allergy in that antibodies do not participate in the process of its occurrence. In this case, the active substances - histamine, tyramine, serotonin, etc., are released into the body as a result of the direct effect of antigens on cells. Manifestations of true and false allergies are very similar. Indeed, in both cases, the reaction is caused by the same substances - histamine.
If there is an increase in the amount of histamine in the blood, there are signs characteristic of allergies, such as fever, urticaria, an increase or decrease in blood pressure, headache and dizziness, and suffocation. These symptoms are manifested in both true allergies and pseudo-allergies.
Difficulties in diagnosis lies in the fact that many allergy tests show a negative result, because immunoglobulins do not come into conflict with antigens. It is possible to recognize the presence of an ailment only by the experience of repeated contacts with the allergen. The release of biologically active substances can occur when eating certain foods, such as eggs, fish, as well as as a result of cell damage during irradiation, contact with acids or alkalis, the action of certain drugs, in extreme cold or heat.
A completely healthy body is able to independently neutralize a large amount of histamine, reduce the activity of this substance to a safe level. But with diseases such as tuberculosis, dysbacteriosis or cirrhosis of the liver, the countermeasure mechanism is violated. Inadequately reacts to the presence of histamine and the body is allergic. Therefore, food rich in proteins can cause a pseudo-allergic reaction. The composition of proteins includes amino acids, the derivatives of which are biologically active substances - such as histamine and tyramine.
Some signs allow to distinguish a true allergy from a false one . True allergy is accompanied by an increased content of class E immunoglobulins in the blood. Also an important indicator is the relationship between the amount of the allergen and the strength of the reaction caused by it. With pseudo-allergies, including food intolerance, the reaction intensifies in case of an increase in the amount of food intolerable to the body, flowering plants, household chemicals, etc. This type of pseudo-allergy, such as food intolerance, manifests itself much more often than true allergy, which is associated with violation of the mechanisms of the immune system. And a true allergic reaction is caused even by a minimal dose of an allergen-containing substance, for example, a drug, plant pollen. In addition, the reaction associated with the failure of immunity often manifests itself in certain seasons, for example, during the flowering of certain plants.
Allergy caused by the pollen of various plants
Of the truly allergic diseases, diseases caused by the pollen of various plants were identified and investigated earlier than others. Their name is hay fever- comes from the Latin word for pollen. Then new experiments and studies were carried out. A compatriot of the East, Blackley, managed to artificially cause various manifestations of allergies when plant pollen contacts damaged areas of the skin, mucous membranes of the eyes and nose. The tests developed by this researcher began to be used later in the diagnosis of allergic diseases and contributed to their successful treatment. As the results of subsequent experiments showed, pollinosis is caused by small pollen that can penetrate into the bronchioles. In most cases, this category includes the pollen of those plants that are pollinated with the help of wind. In addition, it must be sufficiently volatile and remain viable for a long time. Humid environments tend to enhance the effect of such an allergen. Usually grass pollen is more active than shrub or tree pollen.
The vast majority of pollinosis also occurs when exposed to pollen from the most common plants in the area. In the regions of Central Europe, this category includes timothy, fescue, cocksfoot, wormwood, quinoa, poplar, elm, and linden. In the southern strip, the main allergen is ragweed pollen. Therefore, for allergy sufferers, flowering periods of these plants are dangerous, especially in the morning, when a lot of pollen is thrown out.
An allergy is manifested, caused by the ingestion of allergens through the respiratory tract, usually attacks - suffocation, cough, runny nose.
In some cases, pollinosis is combined with other forms of allergies that develop as a result of the action of infections, chemical and medicinal substances, and certain foods.
The ability of products to cause allergies depends on their chemical composition and some other factors. Those that have a more complex protein composition are especially allergenic. These include primarily milk and products made from it, as well as chocolate, eggs, meat, fish, as well as some fruits, vegetables and berries.
Allergy caused food intolerance
A pseudo-allergy caused by certain foods is called a food intolerance. It may be associated with the substances contained in the products: preservatives, dyes, etc. People who are hypersensitive to nitrates are advised to limit the use of black radish, celery, beets, bacon, salted fish.
Dairy intolerance or allergy provoked by the latter is more common in people suffering from diseases of the digestive system - gastritis and gastroduodenitis, cholecystitis, dysbacteriosis. The lack of vitamins also leads to the development of negative reactions.
Usually in the case of food allergies, there are disorders of the digestive system, and urticaria and fever. Dyes, turpentine, mineral oils and other chemicals, in contact with the skin, can cause allergies in the form of dermatitis.
infectious allergy
Infectious allergies can accompany diseases such as tuberculosis and typhoid fever. Sometimes allergens are produced in the body itself due to exposure to very high or very low temperatures or due to some mechanical damage.
Factors affecting the development of allergies :
hereditary predisposition,
certain environmental conditions,
Relaxation of the nervous system
Weakness of the body's immune system (due to stress, overload, previous diseases),
Irrational nutrition,
Smoking;
Abuse of alcoholic beverages
Repeated contact with the allergen (at the first, an inadequate reaction to the allergen does not occur).
Substances that cause hypersensitivity in allergic people are easily tolerated by healthy people.
Also, the development of an allergic reaction may be due to the inability of the body to protect itself from the effects of the allergen that has appeared.
Allergic diseases that are passed from parents to children are called atonic. An inherited allergy is called atopy. The likelihood of developing the disease in a person whose parents suffered from allergies is high.
The reaction of his body to the appearance of an allergen, as a rule, turns out to be fast and very strong. But if the gene responsible for allergy is inherited from one of the parents, the painful reaction will be less pronounced, and may even be completely absent. But repeated exposure to any antigen can cause a malfunction of the immune system even in an organism that is not prone to allergies.
Allergies affect different tissues and organs of the body in different ways. Sometimes substances arising from the interaction of "own" and "foreign" cells cause bronchospasm. In other cases, the vessels of the skin or the muscles of the intestine are primarily affected. And the permeability of capillaries or the mechanism of action of enzymes may be impaired.
Therefore, as a result of allergies, various diseases develop that affect certain organs. These diseases include bronchial asthma, rheumatism, inflammation of the kidneys.
If, due to cholecystitis or other diseases, the amount of bile entering the duodenum is significantly reduced, the digestion process is disrupted. The body does not absorb fats and certain vitamins well. As a result, favorable conditions are created for the vital activity of pathogenic bacteria.
There is a violation of the balance of microorganisms that existed before. Dysbacteriosis develops. The consequence of dysbacteriosis is a change in the permeability of the intestinal walls. They cease to restrain the penetration into the blood of various microbes and the toxins they release. As a result, antibodies are produced and allergic reactions occur. Manifestations of allergies can be different, such as asthma attacks, skin rashes. Further poisoning with microbial waste products leads to a general weakening of the body, to damage to the central nervous system. In this case, the patient's mood and appetite worsens, vitality decreases.
To prevent diseases caused by allergies, it is very important to timely and consistently treat diseases of the digestive system, such as cholecystitis and gastroduodenitis, to combat microbes penetrating the intestines.
Development of allergic reactions
Allergic reactions differ in the speed of their development. According to this principle, they are divided into two categories:
delayed reactions,
Reactions of immediate type.
For human life and health, the most dangerous are those that appear especially quickly. This is within one hour of exposure to the allergen.
Immediate reactions
Slow allergic reactions are not so dangerous. But they can also cause serious illnesses that occur for a long time and shorten the life of the patient.
There are several types of allergy manifestations, depending on the immunoglobulins involved in the reaction and the affected organ.
The first type includes allergic reactions occurring especially quickly. They develop within minutes or hours after exposure to the allergen. It is the reactions of the immediate type that sometimes create life-threatening situations.
To the number allergic manifestations of this type are:
Anaphylactic shock,
swelling of the larynx,
attacks of bronchial asthma,
swelling of the subcutaneous tissue,
Conjunctivitis,
Hives.
The tissues of the disease-prone organism are affected by histamine released from the cells and some other biologically active substances. Allergic reactions are caused by class E immunoglobulins.
Reactions of the cytotoxic type
The second type of allergic reactions is called cytotoxic. The manifestation of this type can be noticeably delayed in time from exposure to the allergen. In this case, cells are damaged by components of the so-called complement - a special protein substance present in the blood, or cytotoxic lymphocytes.
Antibodies of classes C and M are also involved in the process. As a result of allergic reactions of the second type, blood cells are destroyed, kidneys and lungs are damaged, hemolytic anemia develops, and transplanted organs are rejected.
Reactions leading to the development of immune complex diseases
The third type of allergy leads to the development of immune complex diseases.
This is in particular for:
alveolitis,
lupus erythematosus,
serum sickness,
Inflammation of the kidneys, and resulting from infections.
Various allergens can be involved in the reaction: bacterial, medicinal, pollen and opposing immunoglobulins, which in most cases belong to classes C and M. Antigens and antibodies combined into complexes are retained in the blood, attracting leukocytes to themselves and activating the release of enzymes from cells. As a result of these processes, those organs and tissues that are associated with the immune system are affected.
Delayed reactions
The last fourth type of allergy develops due to a delayed type of hypersensitivity. It is characterized by the fact that the reaction to the penetration of the antigen into the body appears only after a day. There are foci of inflammation, and next to them - accumulations of macrophage cells and lymphocytes. The process ends with the formation of granules, scars, necrosis of some tissue areas.
In some cases, several types of allergic reactions appear at the same time. This situation, in particular, occurs with serum sickness or with severe skin lesions.
Sometimes an allergic reaction affects blood clotting or the production of adrenaline.
Types of allergies
Allergic reactions are provoked, they can be various substances that exist in the outside world.
Medications make up a significant group of allergens. Any pharmacological drug under certain conditions can be an irritant. The decisive role here is played by the frequency and doses of taking a particular substance.
Allergens among drugs in most cases are antibiotics, sulfonamides, aspirin, insulin, quinine.
Infectious or biological allergens- these are different microbes and viruses, fungi and worms. The same category includes sera introduced into the body and vaccines containing a foreign protein.
Can act as food allergens any human use Food.
The next category of allergens is presented plant pollen(usually wind pollinated). Among the "record holders" in terms of the number of allergic reactions they cause are the most common plants in one or another band. In various natural zones, this role can be played by ambrosia, birch, poplar, wheat, cotton, plane tree, maple, alder, mallow and etc.
TO industrial allergens relate dyes, turpentine, lead, nickel and many other substances. Allergies can also be caused by mechanical influences, cold or heat.
household allergens represented mainly by the common house dust, animal hair, cleaning products and other household chemicals. They mainly affect the upper respiratory tract.
Depending on the substance that caused the reaction, and on the way the allergen enters the body, the following types of allergies are determined:
- as medicinal
- bacterial
- food,
- respiratory,
- skin, etc.
There are various manifestations drug allergy . The features of the course of the disease are associated with such factors as the state of the body's immune system, the dose of the taken substance containing the allergen, etc.
Drug allergies are divided into several types:
Subacute
Protracted.
Acute manifests itself within an hour after penetration into the body of the allergen and can cause edema, urticaria, anemia and anaphylactic shock.
At subacute Allergy causes fever that develops within 24 hours of contact with the allergen. There may be some other consequences as well.
Protracted the type of allergy causes serum sickness, arthritis, myocarditis, hepatitis, etc. The manifestation of these diseases from the moment of interaction with the allergen can be separated by a rather long period of time, up to several weeks.
Occupational Allergy occurs upon contact with paints and varnishes, synthetic resins, chromium and nickel, oil distillation products. Its most common manifestations are dermatitis and eczema.
From allergies caused by chemicals present in mineral fertilizers, as well as physical irritants - prolonged exposure to sunlight, extreme cold or heat, rural residents are more likely to suffer. Under the influence of these factors, an occupational skin disease develops - dermatitis. Contributes to the development of occupational allergic diseases, the general weakening of the body, caused by disruption of the endocrine, central nervous and digestive systems. At the same time, minor cracks or scratches on the skin are far from safe.
Allergies in children
Allergic diathesis is characterized by increased permeability of the mucous membranes, which contributes to the penetration of allergens. As a result, there is an increased tendency to allergies. Allergic diathesis observed in the youngest children and, in most cases, is inherited. Subsequently, allergic diathesis can be replaced by diseases inherent in older people, such as asthma, urticaria, dermatitis and eczema.
The main manifestations of the disease:
Intertrigo and other types of rashes on the skin,
Increased irritability and excitability,
Loss of appetite.
There are also changes in the biliary tract, an increase in the size of some internal organs, and dysbacteriosis.
A predisposition to diathesis can be identified even before the birth of a child, therefore, according to the presence of allergic diseases in his parents, preventive measures should be taken even during the mother's pregnancy. They consist in the exclusion of the use of products containing allergens by a woman, the timely treatment of infections, the careful use of medicinal substances. Similar measures of protection against allergies are also necessary for the baby - he is given complementary foods later and more carefully, only in the absence of manifestations of diathesis are vaccinations mandatory for children.
eczema in children downstream has certain characteristics. Often the disease occurs under the influence of a hereditary predisposition, and food products act as the allergens that cause it. Children who are formula-fed or who start complementary foods early are more at risk. In the future, eczema may be a reaction to environmental factors - odors, dust, wool, plant pollen, etc. Usually, the face is affected first. It swells, the skin is covered with small bubbles filled with liquid. Developing, the disease is able to capture all new areas of the skin.
Eczema usually resolves completely before children reach school age. But sometimes there is a relapse, which leads to permanent changes in the color and oiliness of the skin and hair.
It also has certain developmental features. bronchial asthma at an early age, and in the event of an attack in children, it is strictly forbidden to use steam inhalations and products containing mustard, as this can enhance the reaction. But infusions or decoctions of medicinal plants have a positive effect.
Allergy diagnostics
Diagnosis of allergies involves two main stages:
The first stage is the determination of the organ that has undergone allergic inflammation;
The second stage is the identification of the allergen that provoked an inadequate reaction.
Special tests for reliable determination of allergens. One can judge the reaction of the body to the effect of a particular element by changing the pulse, inflammation on the skin, the level of immunoglobulins E in the blood serum, and some other indicators.
The simplest tool used to determine the allergic substance is pulse test. It is carried out in this way - if any food or drug causes concern, half an hour after taking it, you need to measure the pulse. The increase in heart rate, compared with the indicators obtained before, can be considered as evidence of intolerance to this substance. Its reception is canceled for several days, and then resumed in small doses, always with a control measurement of the pulse.
elimination method consists in the complete cessation of the use of the product that is suspected of being allergenic. Changes or lack thereof in the patient's well-being should confirm or refute the validity of the assumption.
More complex studies are used in medical institutions. Spend skin tests. For their implementation, special solutions containing one or another allergen are used. These drugs are produced by the pharmaceutical industry. If there is suspicion of intolerance to any substance, then the antigens contained in it can be injected under the skin of the patient using such a solution. In the case of the production of appropriate antibodies, an allergic reaction occurs, as evidenced by inflammation developing on the skin.
But this method sometimes fails. It may, for example, turn out that a person is really allergic to food or plant pollen and the effect of the allergen is manifested in the intestines or bronchi. And skin tests show a negative result, since such a reaction does not affect her. In other cases, on the contrary, after the introduction of the antigen, the skin may become inflamed. However, in the future it turns out that this is simply the result of irritation, and not evidence of an allergy at all.
Sometimes, during skin tests, an allergic reaction can be much stronger than expected, up to serious swelling, bronchospasm, and even anaphylactic shock.
In cases where there is no specially manufactured preparation, a test for intolerance to any product can be carried out differently. For this it is enough to put a small amount under the tongue suspected of being allergic. The validity of such fears should be confirmed by the reaction that develops in the future.
Another method for identifying a tendency to allergies is blood serum analysis. An increase in the amount of immunoglobulins E may indicate such a reaction.
With more complex studies, it is possible to establish against which antigen protective antibodies are produced.
Very risky are the previously widely used provocative tests. Their essence is as follows: a person who is suspected of having an allergic disease is injected with the blood serum of a known allergic person. This is followed by a provocation with exactly the allergen from which the known patient suffered. As a result, the same allergic reaction can occur, manifesting itself in the form of asthma attacks, swelling, skin rash or anaphylactic shock. This allows you to easily and with sufficient accuracy to determine the diagnosis. But the method itself, capable of causing a strong manifestation of the reaction, is too dangerous. Therefore, nowadays it is rarely used, moreover, only in a hospital setting, where there are all the means to provide emergency care.
In some cases, the degree of sensitivity of the body to a particular substance can be determined in the simplest way outside of medical institutions. For example, a small amount of perm, blush, or lipstick can be apply on the skin of the hands and do not rinse for several hours. If itching, redness, and other signs of allergic skin irritation are not noted, the tested drug is considered safe and suitable for use.
Allergy treatment
It provides for the treatment of allergies by a system of measures, which, in addition to a healthy lifestyle, include immunotherapy, diet, and pharmacological preparations.
Currently pharmacological preparations play a paramount role. New medicines are constantly being developed and put into practice. The pharmaceutical industry provides medical institutions with various tablets and ointments, drops and injections.
The most commonly used for the relief of a painful condition caused by allergies, well-known drugs suprastin, fenistil, claritin .
Until recently enjoyed great popularity diphenhydramine, characterized by a low price, therefore the most affordable. It is available in tablets (for oral administration) and in ampoules (for injection under the skin). However, the use of this drug has a serious side effect that negatively affects the general well-being of the patient. Thus, the drowsiness caused by this reduces the reaction on the roads, worsens the ability to work. The use of this substance is incompatible with significant physical and mental stress. An overdose of diphenhydramine can cause especially severe consequences. Therefore, the sale of this drug is now made exclusively by prescription.
To relieve an allergic reaction and the serious condition caused by it, in some cases, in addition to antihistamines, are used adrenaline, ephedrine and other drugs. At allergic conjunctivitis and dermatitis applied externally hydrocortisone ointment . allergic rhinitis treated with a mixture of solutions boric acid, silver nitrate and adrenaline hydrochloride . Special medicines are designed to combat diseases of allergic origin - bronchial asthma, rheumatism, etc.
If the development of allergies is associated with factors such as brain injury, deterioration of the adrenal glands, stress, disruption of the endocrine and nervous systems, general weakening of the body. Therefore, sedatives and restorative agents are also applicable for the treatment of allergic diseases.
Anaphylactic shock and its treatment
The most severe manifestation of an allergic reaction is anaphylactic shock. It can be caused by the repeated introduction of an antigen contained in any drug into the body, regardless of the amount of the substance that provoked the reaction. Usually, injections of a vaccine or serum, novocaine, antibiotics and some other substances lead to such serious consequences. Less often, anaphylactic shock may be associated with other factors. So, in particular, cases of the occurrence of this reaction to an insect bite were recorded.
Some food products also act as allergens that cause shock. These include fresh strawberries and strawberry jam. Children usually suffer from reactions provoked by such substances.
Manifestations of anaphylactic shock are extremely severe. Within a few minutes after contact with the substance that caused the allergy, a sharp deterioration in the patient's well-being is observed, associated with the inhibition of the most important body systems.
Main symptoms - a sharp drop in blood pressure, dizziness, difficulty breathing, noises in the lungs, nausea, pain in the abdomen, skin rash and swelling. Convulsions and fever may occur. There is a blackout or even loss of consciousness. Sometimes the picture of what is happening is not so obvious, only bronchospasm is noted, without any other manifestations of allergy. In this case, it is much more difficult to quickly and correctly determine the diagnosis. Usually, only indications of a previous anaphylactic shock or an already occurring allergic reaction to the same antigen help the doctor to correctly assess the situation.
If a person in a state of anaphylactic shock is not provided with timely medical assistance, death from suffocation or heart failure may occur. Therefore, allergen testing rooms should be equipped with the necessary facilities for emergency care.
To save the life of an anaphylactic patient, the first thing to do is urgent administration of adrenaline . In the future, some other drugs and measures to restore impaired breathing may be required. If anaphylactic shock occurs outside of a medical facility, immediate call a doctor . With the ability, you can independently inject the patient with adrenaline.
To preventive measures anaphylaxis include caution when introducing into the body substances containing foreign protein and other likely allergens (in particular, sera), fixing previous cases of an allergic reaction and accurately identifying the substances that caused them.
Anaphylactic shock is an immediate, extreme manifestation of an allergy that is not so common.
Serum sickness
Serums and other drugs can provoke other forms of allergic diseases. There are similar causes of serum sickness to anaphylaxis. The degree of its development and the presence of complications depend on the frequency and intensity of the introduction of certain drugs into the body.
Usually explicit disease symptoms are observed after an incubation period lasting from several hours to several weeks, most often about 10 days. The patient begins to feel fever and chills, severe headache. These phenomena may be accompanied by nausea and vomiting, soreness of the joints and lymph nodes, and life-threatening edema. As blood pressure falls, the heart rate increases. There is also a rash on the skin. The result of the patient's blood and urine tests, and ECG data show certain abnormalities, indicating the presence of serum sickness.
Doctors, having made a diagnosis, prescribe the appropriate course of treatment. Among the tools needed to combat the disease are antihistamines . In case of swelling of the larynx, also apply adrenaline and ephedrine . Sometimes needed hydrocortisone .
Serum sickness usually occurs from several days to three weeks. If there are no complications, in the future, in most cases, a full recovery occurs. Physicians can only take preventive measures in order to prevent the resumption of such a reaction in the future. However, serum sickness can cause very dangerous complications affecting the heart, liver, kidneys and other internal organs. As a result, encephalitis, hepatitis, myocarditis can develop.
For a warning similar complications, the patient, along with other drugs for 1-2 weeks, should be administered glucocorticoid hormones .
Dermatitis
The use of pharmacological drugs can cause other manifestations of allergic reactions. For example, dermatitis, characterized by rashes on the skin, is usually accompanied by damage to internal organs and disruption of the central nervous system. Contributes to the development of dermatitis the presence of certain diseases - influenza, rheumatism, all kinds of chronic infections. Risk factors also include severe stress, disruption of the endocrine system, improper metabolism, repeated and prolonged contact with potential allergens.
Dermatitis is most often provoked by antibiotics, hormones, anesthetics and some vitamins, as well as sulfa drugs. They can come into contact with the body through injection, ingestion or external use.
Skin rash is not the only manifestation of drug dermatitis . In addition, there is also a feeling of itching and burning of the skin, increased irritability, sleep disturbance, and the temperature rises.
The duration and severity of the disease are related to the rate of detection of the drug that caused the allergy.
Sometimes it is enough to relieve the symptoms of dermatitis stop taking the drug to which hypersensitivity has been found.
But a more complex course of the disease requires the intake of substances that alleviate the patient's condition. These include, in particular, calcium chloride and sodium hyposulfite, antihistamines . Erupted skin is treated hydrocortisone ointment . In the vast majority of cases, the patient recovers completely, although the disease, under adverse circumstances, can drag on for several weeks.
Hives
The range of allergens contributing to the development of acute urticaria and extensive allergic edema is much wider. This disease can be caused by contact with plant pollen, taking any food or medicine, ultraviolet radiation, penetration of helminths or bacteria into the body, insect venom, etc. The presence of a tumor also increases the likelihood of urticaria.
The action of histamine, released by the body during the penetration of the allergen, leads to a change in the degree of permeability of the vascular wall. As a result, reddening of the skin occurs with the formation of blisters of various shapes and sizes, or significant allergic edema occurs, painful and dense. Symptoms diseases are itching, nausea and vomiting, fever and chills. Edema can affect the face and other parts of the body, leading to difficulty in swallowing and breathing. The most dangerous are those that affect the larynx, brain, esophagus or intestines. Such edema in some cases endanger the life of the patient. However, they usually disappear gradually.
Violation of the permeability of the walls caused by allergies can cover not only the vessels of the skin, but also the vessels of the internal organs. Therefore, urticaria can be accompanied by myocarditis and some kidney diseases. It also contributes to the occurrence of arthritis affecting the joints. Features of the treatment of urticaria depend on the nature of the allergen that caused it and on the degree of development of the reaction. In any case, it is necessary to remove allergen-containing substances from the body as soon as possible.
In these diseases, the pharmacological agents used include, in particular, antihistamines, sodium chloride, epinephrine and ephedrine, hydrocortisone and some other substances. Special measures are taken to prevent complications.
Patients with urticaria, among other means, are prescribed a dairy-vegetarian diet and a temporary refusal to use table salt . Strengthening the body's defenses can contribute to daily intake ascorbic acid .
Pollinosis or hayfever
Another fairly common allergic disease is pollinosis or hay fever. It mainly affects the mucous membranes of the eyes and respiratory organs, and may also be accompanied by a skin rash. The development of pollinosis is observed during the flowering period of plants. The danger of this disease lies in the likelihood of subsequent development of bronchial asthma on its basis. Other complications are possible, such as sinusitis, frontal sinusitis, or bacterial conjunctivitis.
Feature hay fever - depending on the seasons. An outbreak of diseases of this type occurs in the spring period of tree flowering, in the middle of summer, the time of flowering of cereals, and at the end of summer - the beginning of autumn, the time of flowering of weeds.
There may be manifestations of pollinosis in various combinations of conjunctivitis, rhinitis and attacks of asthma-type dyspnea. In some cases, they are joined by neurodermatitis or urticaria. With an exacerbation of hay fever, increased sneezing, a runny nose, swelling of the mucous membranes of the nose and difficulty breathing, a burning sensation or pain in the eyes, swelling of the eyelids, redness of the mucous membranes of the eyes, lacrimation and photophobia are noted. There may be attacks of suffocation such as asthmatic, especially in the evening. In some cases, rashes appear on the skin. Rarely, the course of the disease is accompanied by fever, general weakening of the body and other manifestations of intoxication caused by pollen: headache, insomnia, profuse sweating, etc.
Studies conducted in medical institutions reveal the presence of changes in the composition of the patient's blood. Often x-rays show swelling in the maxillary sinuses.
The degree of development of the disease can be different - from minor and harmless manifestations of conjunctivitis or rhinitis to severe asthma attacks.
Often, hay fever manifests itself in a similar way to illnesses such as influenza, bronchitis, or conjunctivitis. This can mislead the doctor when making a diagnosis. But with repeated seasonal exacerbations, the essence of what is happening becomes obvious.
Allergic reactions in hay fever are observed only during the period of distribution of pollen of the plants causing the disease. Even after the rain has knocked down the pollen carried by the wind, the symptoms of pollinosis are weakening.
Outside of the flowering period, the disease may not appear at all or be slightly reminded of itself by short-term symptoms caused by the use of products associated with the allergenic plant, such as nuts or birch sap.
Exacerbations and severe complications, including anaphylactic shock, in a patient with hay fever can also be caused by improper use of pharmacological agents, primarily antibiotics. In this case, the development of an allergy to new substances, hypersensitivity to which has not been previously noted, is not ruled out.
As with other allergic diseases, hay fever should first of all stop contact with the allergen . For this purpose, even moving to another area for the period of flowering of dangerous plants is not ruled out. In extreme cases, you can limit yourself to staying within the walls of the house, go out less, where the effect of pollen carried by the wind can affect. If it is not possible to avoid being outside, you should rinse your nose and take a shower after returning home.
A special role belongs diet. It is necessary to exclude from the diet those foods that are potential allergens.
To combat pollinosis, which manifests itself in inflammation of the mucous membranes of the nose and eyes, are used antihistamines . Conjunctivitis caused by hay fever is treated hydrocortisone or dexamethasone . In some cases, apply ephedrine and adrenaline . If the disease has spread to the bronchi, and attacks of shortness of breath occur, the same drugs that are prescribed to patients come to the fore.
With swelling of the larynx, not removed by other methods, can be applied surgical intervention .
Strengthening the immune system as a method of treating allergies
A special role in recovery belongs to strengthening the immune system.
Immunity is the body's defenses, its resistance to various infections or foreign substances. There is resistance to the effects of bacteria, viruses or toxins through a system of adaptations and reactions, some of which are inherited, and some are acquired later.
Innate immunity protects a person from all those diseases that affect only animals. The degree of his strength varies from absolute to relative immunity.
Acquired immunity is divided into two types:
Active,
Passive.
Active is produced as a result of the introduction of a vaccine or develops after a certain infectious disease has been transferred.
Passive associated with the production of antibodies against any infectious agent. This happens when serum is injected. Such immunity is unstable, and it can only last for a few months.
It is thanks to the action of the immune system that control over the maintenance of the stability of the antigenic and cellular composition is carried out. But the immune system can fail due to intoxication of the body due to the action of infections, all kinds of toxins and a number of other adverse factors.
The occurrence of allergic reactions is closely related to the state of the immune and central nervous systems. Therefore, among the measures to prevent allergies, a special role should be given to those aimed at strengthening the body's defenses.
It helps to increase the body's resistance by taking infusions of certain medicinal plants that relieve fatigue and increase overall tone.
The most famous and effective of them is ginseng growing in the Far East. Its roots are especially valuable. Tinctures and powders used in medicine are made from them. These healing agents relieve fatigue, increase cardiac activity and are especially beneficial for an organism weakened by an illness. But there are a number of contraindications to its use.
Root and leaf extracts can also have a tonic effect. eleutherococcus . If you take this remedy for more than 2 weeks, positive changes such as increased mood, performance, improved vision and hearing will become apparent. Therefore, Eleutherococcus is taken in case of exhaustion and hypotension - low blood pressure.
With a number of diseases, alcohol tinctures of seeds will have a beneficial effect. schisandra chinensis . In the homeland of the mentioned plant, the Far East, decoctions and infusions from lianas, leaves and fruits of magnolia vine are also widely used. The use of this remedy helps not only relieve fatigue and improve performance, but also promotes the outflow of bile, and therefore is used for cholecystitis. The drug is also effective in hypotension. The ability to increase immunity and improve the functioning of the nervous system makes it possible to include lemongrass in the number of drugs designed to resist cancer.
They are also among the immune boosters. aralia manchurian, leuzea safflower and zamaniha . Alcohol tincture from young aralia roots stimulates the activity of the central nervous system, increases blood pressure, relieves fatigue and strengthens the body weakened by the disease. A tincture of dried rhizomes of zamanihi is used to treat depression, hypotension, and some forms of diabetes. The same remedy is a general tonic, contributing to the restoration of strength after serious illnesses or tedious work. Many diseases can heal Leuzea. This plant has been used in folk medicine since time immemorial. At present, the pharmaceutical industry produces a drug known as "liquid leuzea extract". It also serves to relieve overwork, improve working capacity, increase blood pressure. The drug based on Leuzea promotes the speedy recovery of patients who have undergone a major operation.
Among the tonic herbs we can mention rhodiola rosea . From its root, which has a golden hue, infusions, decoctions and extracts have long been made.
In addition to improving working capacity and relieving fatigue, Rhodiola can help treat diseases of the central nervous system and heal injuries. It neutralizes to some extent the dangerous effects of radioactive substances and metal dust harmful to health.
Allergy: prevention of allergic diseases
Prevention of allergic diseases includes a number of measures.
Since a variety of factors are capable of provoking an inadequate response of the body:
Food,
plant pollen,
pharmacological preparations,
household chemicals,
animal fur,
Cold, etc.
That and preventive measures should be aimed at the general strengthening of the body and the removal of those factors that increase the risk to the greatest extent.
The main conditions for getting rid of allergic diseases:
1. healthy lifestyle,
2. moderate exercise,
3. rational mode of work and rest,
4. properly organized nutrition,
5. creation of a favorable ecological environment.
Should refuse self-medication and use pharmacological preparations only as prescribed by a doctor to prevent drug allergies. It is important to note those drugs that have already caused intolerance in the past, and in no case should they be taken again. It is undesirable to start taking several new drugs at the same time, since in the case of an allergy it will be difficult to identify the substance that caused the reaction.
Improving the functioning of the immune system also plays an important role in preventing drug allergies and other types of this disease. Here, hardening, accustoming the body to endure cold or heat, a sharp fluctuation in ambient temperature, will provide invaluable help. Hardening exercises begin from a very early age, of course, taking into account the state of health and the individual characteristics of the child. In order to train the thermoregulatory apparatus, various methods can be applied, for example, wet rubbing, massage, bathing and air baths. But when hardening children, it is necessary to increase the load gradually, in proportionate doses. Too long and intense exposure to hardening factors (cold water, sunlight) should be avoided, as this can cause the opposite of the desired result.
They are used to strengthen the body, increase its resistance to disease and physical education. But if moderate physical activity promotes health, then intense training, on the contrary, can have a negative effect. Also unfavorable and overwork during physical or mental work.
Gotta try avoid nervous breakdowns. After all, as you know, difficult experiences can exacerbate an existing allergic disease or even cause a new one, in particular, bronchial asthma and some types of skin lesions.
Positive emotions, good mood reduce the likelihood of allergies. Therefore, it is necessary to learn to control your feelings and manage your emotional mood even if difficult life situations arise. Favorite books, classical music, embroidery or knitting, communication with four-legged friends, pleasant walks, etc. will help in this. At home and at work, it is necessary to create, as far as possible, a healthy environment.
In order to avoid the accumulation of dust in the room, after 2-3 days it is necessary to carry out wet cleaning. Carpets, sofas, curtains need to be vacuumed. We should not forget about the need to remove dust from books, paintings, televisions, computers. Special air purifiers will also help create a favorable environment. In the kitchen, it is desirable to install an exhaust device that removes products of incomplete combustion of gas and other harmful substances from the room. And of course, a necessary condition for maintaining a good microclimate is the rejection of active or passive smoking.
If at work you have to work with harmful substances that can cause dermatitis. In this case, it is especially necessary take good care of your skin hands, timely wash off dyes and solvents that pollute it, cause irritation. Sometimes the use of skin-protecting gloves helps. Some nourishing creams are used as an emollient. Even small cracks and scratches should be treated with an iodine solution, since their presence facilitates the penetration of allergens. Oily substances should not be heavily sprayed or splashed, protective screens are installed to limit their contact with the skin.
Particularly serious safety measures are provided for in the case of work in production with radioactive preparations, which, among other things, can cause allergic diseases. Workers must be provided special protective clothing, rooms are equipped with exhaust ventilation. For the storage and transportation of radioactive materials, hermetic containers are provided, the reliability of which must be controlled.
Caution requires the use of such substances necessary in the household as dyes and solvents, glues "Moment", "Octopus", kerosene and gasoline. After applying them the room must be well ventilated.
Allergies are often caused by various lotions, shampoos, deodorants, creams, blush and lipsticks, colognes and perfumes, washing powders and other cleaning products.
Choose perfumes or household chemicals with great care. And if signs of intolerance appear (shortness of breath, skin rashes, etc.), immediately stop using. Drinking water is best filtered.
For the prevention of bacterial allergies, it is important to timely elimination of foci of infection present in the body(in particular, the treatment or removal of teeth affected by caries).
If you suspect an allergy or if allergic diseases have already been identified, you will have to resort to more drastic measures. For example, replace feather pillows with synthetic ones, do not wear clothes made of wool or natural fur, remove items that accumulate dust (carpets, etc.). It is even better to clean boots and boots with cream outside the apartment (on the balcony or on the landing).
In the presence of diseases of the digestive system, the main danger is food allergies. To prevent it, it will be necessary avoid eating spicy, smoked, salty and pickled foods. Desirable limit the intake of chocolate, coffee and chicken eggs, and use boiled or condensed milk.
The main allergens that cause allergies
Some allergens have already been considered, but we will dwell on them in more detail.
airborne allergens (aeroallergens) are substances that cause an allergic reaction (sensitization) in the body, getting into the respiratory tract.
In order for an air allergen to have a pathogenic effect, it must be contained in the air in a significant amount, its particles must be relatively small and remain suspended for a long time. Air allergens are plant pollen, spores of fungi, including molds, animal products (parts of the vital activity of mammals, insects, mites), dust (organic and inorganic nature), and occasionally algae.
In the external environment, many airborne allergens, such as plant pollen or fungal spores, appear only at certain times of the year for each of them. Separately, they meet sporadically. During the period of abundant flowering, the concentration of pollen can be high. It is affected by air temperature and humidity, wind speed and direction. As the temperature rises, that is, usually in the middle of the day, the release of pollen by plants and spores by fungi increases. Also, the concentration of spores of many fungi and pollen of some plant species (for example, ragweed) increases in the air at high humidity. Typically, the concentration of aeroallergens increases at a wind speed of about 24 km/h. With a further increase in wind speed, the concentration of the allergen decreases. The smaller the aerosol particles containing the allergen, the longer they remain in suspension. The shape of the grains also affects the stability of the aerosol with pollen.
Plants are a very common cause of allergic rhinitis and asthma. From plants, grasses, weeds and trees can cause allergies. However, plants do not cause allergies on their own, but because they produce pollen during the flowering period. Pollen is transported in many ways: with the help of insects, animals or wind. Pollen often causes allergy symptoms, but this does not mean that there is an allergy to the plants themselves. For example, if there is an allergy to oak pollen, then it is not to the tree itself. You can not be afraid to step on oak parquet and safely use oak furniture.
In general, a very small percentage of all herbs produce pollen that provokes allergies or asthma. Basically, these allergenic species are forage or lawn. Pollen from about 50 species of flowering plants are known to cause allergies. These include cereals (rye, meadow timothy, fescue, foxtail, bluegrass) and plants of the Compositae family (dandelion). Allergies can occur to the pollen of many other plants: wormwood, quinoa, sorrel. Moreover, an allergic reaction to the pollen of one of these plants indicates hypersensitivity to the rest.
Much more often than other plants, the cause of allergies and asthma attacks is ragweed. Many allergy sufferers who are sensitive to ragweed are also affected by chaff, a weed that grows in flax crops. The flowering period of ragweed usually begins in mid-August and ends in October and / or before the first frost. Ambrosia releases most of its pollen between 6 and 11 o'clock in the morning. In hot and humid weather, pollen is usually less.
Tree pollen is smaller than grass pollen. The flowering period of trees that produce allergenic pollen usually lasts from late winter or early spring to early summer. As a result, the risk of suffering from tree pollen is lower than from grass pollen.
Trees that produce the most allergenic pollen include elm, willow, poplar, birch, beech, oak, chestnut, maple, boxwood, ash, and some types of cedar. Coniferous trees (spruce, pine, fir) are wind pollinated. Although there is a significant amount of pollen around them, it rarely causes allergies. Many allergy sufferers believe that poplar fluff is the cause of their disease. In fact, they are more likely to be affected by grasses whose pollen peak coincides with the dispersal of poplar seeds. Poplar pollen causes allergies much less often than it is credited with.
The flowers produce a heavy and sticky pollen that is carried by sticking to the body of insects and animals. Therefore, flowers, as a rule, do not cause allergies. In most cases, when an allergic disease is associated with the flowering of roses or other flowers, in fact it is caused by the pollen of nearby grasses and trees. Allergies to flowers can rarely develop in people who have close contact with them, such as employees of flower greenhouses or shops.
Sometimes the cause of an allergic reaction in the oral cavity is the result of a cross-reaction between pollen and certain foods. By itself, the reaction of the oral cavity is manifested by swelling, itching of the oral mucosa in contact with food - lips, tongue, pharynx, palate. Those suffering from such a reaction should not eat raw foods, especially during the flowering season of plants whose pollen causes them allergies. If you are allergic to birch pollen, it is not recommended to eat apples, pears, celery, carrots, potatoes, kiwi, hazelnuts; if you are allergic to ragweed pollen, it is not recommended to eat watermelons, melons, cucumbers; if you are allergic to tree and grass pollen, it is not recommended to eat apples, peaches, oranges, pears, cherries, cherries, tomatoes, carrots, hazelnuts, etc.
As a rule, allergy to the fruits of trees, on the pollen of which signs of allergy are noted, the allergy does not develop.
In general, in order for an allergic reaction to plant pollen to occur, contact with it is necessary for at least one flowering season. In infants, such a reaction, as a rule, is not observed, as a result of which they do not develop allergies.
To avoid exposure to pollen allergens, it is recommended :
Avoid prolonged exposure to the open air, especially in the early morning and late evening hours, when the concentration of pollen in the air is maximum;
If you still need to work outdoors, you need to wear a mask or, even better, a respirator;
Do not go outside on warm windy days and afternoons when the concentration of pollen in the air is especially high;
Since grass pollen is released into the air mainly at the end of the day, it is best to stay indoors at this time;
While at home, close windows and doors tightly and use an air purifier;
Wash your hair before bed to prevent allergens that have settled on your hair from getting into the pillow;
Dry your laundry indoors, as outdoors can act as a pollen trap, introducing a huge amount of "fresh" allergens into your home.
It can also cause an attack of bronchial asthma and allergic rhinitis. mold. Mold spores are present outdoors and indoors. The danger of mold spores is that their concentration in the air is much higher than the concentration of plant pollen. Unlike plant pollen, which is seasonal, fungal spores are present in the air almost all year round. The peak concentration of fungal spores occurs in the summer. Because molds grow indoors, they attack the immune system all year round. Outdoors, mold grows on fields planted with corn or wheat, on compost, hay, fallen leaves, cut grass, as well as on certain foods - tomatoes, corn, pumpkin, bananas, bread, etc. Not all fungi cause allergic rhinitis and/or asthma. Fungi that produce "dangerous" pollen include Cladosporum and Alternaria. Cladosporum spores are found everywhere in huge numbers, except for the North and South Poles, and Alternaria grows only outdoors. They are the most common cause of allergies.
As a result of scientific research, it has been established that in children with allergies resulting from contact with fungi of the genus Aspergillus, an asthma attack develops immediately when particles (spores) of fungi enter the lungs. Inhalation of spores of this type of fungus contributes to the development of not only asthma, but allergic pneumonitis and severe bronchopulmonary disease - allergic bronchopulmonary aspergillosis.
Antibiotics of the penicillin group, widely used in the treatment of various infections, are produced by fungi of the genus Penicillinum. However, they do not cross-react with the spores of these fungi. Allergic people sensitive to fungi of the genus Penicillinum can safely use antibiotics.
Even when mowing the lawn or during activities of this kind, asthma or other allergic diseases are often exacerbated. This is usually caused by mold spores. Patients who are allergic to fungi of the genus Penicillinum may develop an allergy to the oral cavity when eating Roquefort or Camembert cheeses, since molds of this genus are present in the thickness and on their surface.
You can suspect that molds are the cause of allergies by the following signs :
Allergic rhinitis bothers most of the year, and not just in a certain period;
If allergy symptoms worsen during the summer months - especially near untidy arable fields or while working in the garden.
To avoid contact with mushroom allergen , you should adhere to the following recommendations: do not rake leaves, mow lawns, shovel compost heaps, agricultural work, do not go to the forest; where contact with mold is possible, wear a mask or respirator; fight dampness in living quarters, periodically wash damp places with bleach to destroy molds and prevent their growth. A solution of lime dissolved in three parts of water is usually effective.
In addition to mold, one has to face indoors indoors, an extremely dangerous allergen is house dust. In addition to mold particles and their spores, it contains micromites, insect excretions, particles of animal wool and dander, particles of various fibers such as acrylic, viscose, nylon, cotton, etc., particles of wood and paper, particles of hair and skin, tobacco ash , plant pollen. House dust is not dirt or the result of poor cleaning. It is always present in any room, even never visited.
The house micromite is the strongest allergen of house dust. The allergenicity of household micromites is 10-100 times higher than the allergenicity of house dust in general. These eight-legged arachnids are ubiquitous. They can only be seen with a microscope. They feed on particles of the epidermis of humans and animals, fungi and waste that form house dust. Especially a lot of micromites in mattresses, pillows, carpets, furniture upholstery, soft toys. As a rule, one has to deal with the products of their vital activity and their decaying remains. The mattresses on which they sleep contain up to several million house mites. This explains the fact that asthma and other allergic diseases worsen at night.
The second strongest allergen present in house dust is pet dander. It often causes allergic rhinitis and asthma attacks. This allergen is present even in homes where there is no cat or dog, getting there through the hands and clothes of pet owners visiting the house. In addition to pet dander, the cause of allergic reactions is the urine of mice and rats. Scientific observations have shown that the waste products of cockroaches are also powerful allergens that contribute to the occurrence of asthma attacks, especially in children.
Airborne allergen indoors can be latex. Latex particles are present in large quantities in the air of hospital rooms. The main source is rubber gloves, which are used by medical staff. In urban areas close to freeways, allergy sufferers are at risk because the latex is found in the rubber microparticles of airborne tires.
food products indoors can also be a source of airborne allergens. Very often, an allergic reaction occurs as a result of inhaling allergens when cooking fish and seafood. Allergic rhinitis and baker's asthma have also been observed from flour inhalation.
Airborne allergens may be the cause professional allergic diseases. Occupational asthma is caused by more than 250 industrial substances.
Besides, perfumes, perfumery usually have an irritant odour, which can exacerbate both allergic and non-allergic rhinitis.
Strong odors like smells of petroleum products(gasoline, kerosene, etc.), organic solvents, diesel exhaust, and the smell of heated cooking oils cause allergies and asthma.
Smoking can also cause bronchial asthma and other allergic diseases. It has now been proven that active and passive smoking can cause bronchial asthma and other allergic diseases. Tobacco smoke is a major residential air pollutant. Passive smoking, inhalation of air filled with tobacco smoke, increase the manifestation of allergic respiratory diseases.
Another substance present in the air of residential enclosed spaces - formaldehyde, which gets into it from particle boards and furniture, tobacco smoke, gas stoves, foam insulating materials, carbon paper. Its concentration is especially high in industrial enclosed spaces. Lots of irritants in poorly ventilated areas. They accumulate: hydrocarbons, ammonia, acetic acid from the copying equipment, insecticides, carpet cleaners, combustion products, tobacco smoke. Sometimes contaminants enter the room from the outside. For example, air entering a building's ventilation system from a street with heavy truck traffic leads to an increase in indoor ozone and nitrogen dioxide levels.
Exists a range of symptoms that indicate exposure to indoor air allergens . So, allergic symptoms appear during cleaning, making the bed or changing blankets and bed linen. In addition, allergy symptoms are disturbing throughout the year, and not periodically. Exacerbations occur more often indoors than outdoors, on waking or during sleep.
Sometimes sick home syndrome occurs in people who live or work in homes where poor ventilation and air exchange is slow. Pollutants, reaching high concentrations, enter the human body during breathing. The most common complaints in this syndrome are irritation of the conjunctiva and respiratory tract.
IN atmospheric air contains the main pollutants. The main air pollutants several decades ago were sulfur dioxide and soot particles that entered the atmosphere as a result of burning coal. Now the role of these pollutants in the whole world has significantly decreased, excluding natural sources of these pollution, such as volcanoes, but at the same time, an increase in the number of cars has led to increased concentrations of ozone, nitrogen oxides and fine particulate matter in the atmospheric air. Elevated ozone sometimes contributes to the development of an asthma attack, and nitrogen oxides and ozone increase the reaction to an allergen in patients with allergic rhinitis and asthma.
First, most practical and effective way to deal with allergies - this is a restriction of contact with the allergen. If we eliminate or reduce the degree of exposure to substances that surround us and cause an allergic reaction, then the symptoms of allergies are weakened or disappear altogether.
About a third of a person's life is spent in bed. The main and most aggressive allergen of house dust is a micro mite, therefore, all efforts should first of all be directed to combating it. Although it is almost impossible to completely eradicate them (females lay 20 to 50 eggs every three weeks), it is possible to minimize their detrimental effect.
Measures that will significantly reduce the frequency of exacerbations, the severity of asthmatic and allergic symptoms, and reduce the need for medications.
1. Cleaning - clean the room with a vacuum cleaner at least once a week. It is advisable to use a washing vacuum cleaner. If you suffer from asthma or allergies, wear a dust mask while cleaning.
2. Carpets and Draperies - Get rid of rugs and thick rugs. If all carpets cannot be removed, they must be treated with substances that deactivate dust mite allergens. In addition, it is advisable to replace heavy draperies and blinds with easy-washable curtains and curtains.
3. Bed - put on all pillows, blankets special anti-allergic covers (pillowcases and duvet covers). Wash bedding every two weeks in hot water (at least 70°C), use pillows, blankets and bedspreads only made of synthetic materials. Discard feather (down) blankets and pillows; place your bed in the driest place in your home, use an air purifier and/or dehumidifier if possible to keep the humidity at least 50%.
4. Furniture - use furniture made of wood, vinyl, plastic, leather, but without fabric upholstery.
5. Try not to clutter up the room so that dust does not accumulate and the room is easier to clean. Do not hang pictures, photographs on the walls, do not use large pillows. Limit blankets, books, and other personal items that can collect dust.
6. If your child has allergies or asthma, try to limit the number of soft toys to a few that are machine washable.
The source of allergens are all living things that live in your house (cat or dog). With dandruff and saliva, they secrete proteins - proteins that are powerful allergens. Dead skin cells not only of humans, but also of your pets serve as food for dust mites. Individuals with asthma or allergies should not adopt a cat or dog. But if they already live with you, it is extremely difficult to part with them. Therefore, if you do not want to look for new owners for your pets, the following measures should be applied: increase the stay of your pet outside the living quarters; if the previous recommendation is not feasible, keep the animal out of the allergy sufferer's room and bed; warn all family members, after petting the animal, to wash their hands thoroughly before interacting with an allergic person; be sure to wash your pet once a week.
Outdoor mold spores enter the home through an open window or door and ventilation. Indoors, mold can grow all year round, preferring dark, damp places like basements and bathrooms. Molds grow under carpets, pillows, mattresses, air conditioners, trash cans and refrigerators. Mold Restrictions- extremely important measure:
Avoid damp places in the house, such as a room with a leaky ceiling; use a desiccant to reduce moisture in these areas;
Turn the clothes dryer so that moist air goes towards the window or door, and not into the depths of the dwelling;
Ventilate the bathroom well after a shower or bath;
Use special products to clean surfaces where moisture usually accumulates, around the toilet, sink, shower, bathtub, washing machine, refrigerator, etc.;
Remove any visible mold on ceilings, walls, floors with special products;
Take out the trash can in time and wash it regularly so that the mold does not grow;
Dry shoes and clothes, but do not hang them outside, where fungal spores can settle on them;
Limit the number of houseplants as mold can grow in their soil;
If you suffer from asthma or allergies, remove any plants around the house; you let it "breathe" and reduce the humidity inside.
This term refers to a group of allergic reactions that develop in sensitized animals and humans 24-48 hours after exposure to an allergen. A typical example of such a reaction is a positive skin reaction to tuberculin in antigen-sensitized tuberculosis mycobacteria.
It has been established that the main role in the mechanism of their occurrence belongs to the action sensitized lymphocytes for allergen.
Synonyms:
- Delayed type hypersensitivity (DTH);
- Cellular hypersensitivity - the role of antibodies is performed by the so-called sensitized lymphocytes;
- Cell-mediated allergy;
- Tuberculin type - this synonym is not quite adequate, since it represents only one of the types of delayed-type allergic reactions;
- Bacterial hypersensitivity is a fundamentally incorrect synonym, since bacterial hypersensitivity can be based on all 4 types of allergic damage mechanisms.
The mechanisms of a delayed-type allergic reaction are fundamentally similar to the mechanisms of cellular immunity, and the differences between them are revealed at the final stage of their inclusion.
If the activation of this mechanism does not lead to tissue damage, they say about cellular immunity.
If tissue damage develops, then the same mechanism is referred to as delayed allergic reaction.
The general mechanism of an allergic reaction of a delayed type.
In response to the ingestion of an allergen, the so-called sensitized lymphocytes.
They belong to the T-population of lymphocytes, and in their cell membrane there are structures that act as antibodies that can combine with the corresponding antigen. When the allergen enters the body again, it combines with sensitized lymphocytes. This leads to a number of morphological, biochemical and functional changes in lymphocytes. They manifest as blast transformation and proliferation, increased synthesis of DNA, RNA, and proteins, and secretion of various mediators called lymphokines.
A special type of lymphokines has a cytotoxic and inhibitory effect on cell activity. Sensitized lymphocytes also have a direct cytotoxic effect on target cells. Accumulation of cells and cell infiltration of the area where the connection of the lymphocyte with the corresponding allergen occurred, develop over many hours and reach a maximum after 1-3 days. In this area, there is destruction of target cells, their phagocytosis, and an increase in vascular permeability. All this manifests itself in the form of an inflammatory reaction of a productive type, which usually occurs after the elimination of the allergen.
If the elimination of the allergen or the immune complex does not occur, then granulomas begin to form around them, with the help of which the allergen is separated from the surrounding tissues. The granulomas may include various mesenchymal macrophage cells, epithelioid cells, fibroblasts, and lymphocytes. Usually, necrosis develops in the center of the granuloma, followed by the formation of connective tissue and sclerosis.
immunological stage.
At this stage, the thymus-dependent immune system is activated. The cellular mechanism of immunity is usually activated in cases of insufficient effectiveness of humoral mechanisms, for example, when the antigen is located intracellularly (mycobacteria, brucella, listeria, histoplasm, etc.) or when the cells themselves are the antigen. They can be microbes, protozoa, fungi and their spores that enter the body from the outside. Cells of own tissues can also acquire autoantigenic properties.
The same mechanism can be activated in response to the formation of complex allergens, for example, in contact dermatitis that occurs when the skin comes into contact with various medicinal, industrial and other allergens.
pathochemical stage.
The main mediators of type IV allergic reactions are lymphokines, which are macromolecular substances of a polypeptide, protein or glycoprotein nature, generated during the interaction of T- and B-lymphocytes with allergens. They were first discovered in in vitro experiments.
The secretion of lymphokines depends on the genotype of lymphocytes, the type and concentration of the antigen, and other conditions. Testing of the supernatant is carried out on target cells. The release of some lymphokines corresponds to the severity of an allergic reaction of a delayed type.
The possibility of regulating the formation of lymphokines has been established. Thus, the cytolytic activity of lymphocytes can be inhibited by substances that stimulate 6-adrenergic receptors.
Cholinergics and insulin enhance this activity in rat lymphocytes.
Glucocorticoids apparently inhibit the formation of IL-2 and the action of lymphokines.
Group E prostaglandins change the activation of lymphocytes, reducing the formation of mitogenic and inhibiting macrophage migration factors. Neutralization of lymphokines by antisera is possible.
There are various classifications of lymphokines.
The most studied lymphokines are the following.
Factor inhibiting macrophage migration,
- MIF or MIF (Migration inhibitory factor) - promotes the accumulation of macrophages in the area of allergic alteration and possibly enhances their activity and phagocytosis. It also participates in the formation of granulomas in infectious and allergic diseases and enhances the ability of macrophages to destroy certain types of bacteria.
Interleukins (IL).
IL-1 is produced by stimulated macrophages and acts on T-helpers (Tx). Of these, Th-1 under its influence produce IL-2. This factor (T-cell growth factor) activates and maintains the proliferation of antigen-stimulated T-cells, regulates the biosynthesis of interferon by T-cells.
IL-3 is produced by T-lymphocytes and causes the proliferation and differentiation of immature lymphocytes and some other cells. Th-2 produce IL-4 and IL-5. IL-4 enhances the formation of IgE and the expression of low-affinity receptors for IgE, and IL-5 - the production of IgA and the growth of eosinophils.
chemotactic factors.
Several types of these factors have been identified, each of which causes chemotaxis of the corresponding leukocytes - macrophages, neutrophilic, eosinophilic and basophilic granulocytes. The latter lymphokine is involved in the development of cutaneous basophilic hypersensitivity.
Lymphotoxins
cause damage or destruction of various target cells.
In the body, they can damage cells located at the site of formation of lymphotoxins. This is the nonspecificity of this damage mechanism. Several types of lymphotoxins have been isolated from an enriched culture of human peripheral blood T-lymphocytes. At high concentrations, they cause damage to a wide variety of target cells, and at low concentrations, their activity depends on the type of cells.
Interferon
secreted by lymphocytes under the influence of a specific allergen (the so-called immune or γ-interferon) and nonspecific mitogens (PHA). It is species specific. It has a modulating effect on the cellular and humoral mechanisms of the immune response.
Transfer factor
isolated from dialysate of lymphocytes of sensitized guinea pigs and humans. When administered to intact gilts or humans, it transfers the "immunological memory" of the sensitizing antigen and sensitizes the organism to that antigen.
In addition to lymphokines, the damaging action involves lysosomal enzymes,
released during phagocytosis and cell destruction. There is also some degree of activation Kallikrein-kinin system,
and involvement of kinins in damage.
pathophysiological stage.
In a delayed-type allergic reaction, the damaging effect can develop in several ways. The main ones are the following.
1. Direct cytotoxic effect of sensitized T-lymphocytes
on target cells, which, due to various reasons, have acquired autoallergenic properties.
Cytotoxic action goes through several stages.
- In the first stage - recognition - the sensitized lymphocyte detects the corresponding allergen on the cell. Through it and the histocompatibility antigens of the target cell, contact of the lymphocyte with the cell is established.
- In the second stage - the stage of a lethal blow - the induction of a cytotoxic effect occurs, during which the sensitized lymphocyte carries out a damaging effect on the target cell;
- The third stage is the lysis of the target cell. At this stage, blistering of the membranes develops and the formation of a fixed frame with its subsequent disintegration. At the same time, swelling of mitochondria, pycnosis of the nucleus is observed.
2. Cytotoxic effect of T-lymphocytes mediated through lymphotoxin.
The action of lymphotoxins is nonspecific, and not only the cells that caused its formation, but also intact cells in the zone of its formation can be damaged. Cell destruction begins with damage to their membranes by lymphotoxin.
3. Release of lysosomal enzymes during phagocytosis damaging tissue structures. These enzymes are secreted primarily by macrophages.
An integral part of delayed-type allergic reactions is inflammation, which is connected to the immune response by the action of mediators of the pathochemical stage. As with the immunocomplex type of allergic reactions, it is connected as a protective mechanism that promotes the fixation, destruction and elimination of the allergen. However, inflammation is both a factor in damage and dysfunction of those organs where it develops, and it plays an important pathogenetic role in the development of infectious-allergic (autoimmune) and some other diseases.
In type IV reactions, in contrast to inflammation in type III, macrophages, lymphocytes and only a small number of neutrophilic leukocytes predominate among the focus cells.
Delayed-type allergic reactions underlie the development of some clinical and pathogenetic variants of the infectious-allergic form of bronchial asthma, rhinitis, autoallergic diseases (demyelinating diseases of the nervous system, some types of bronchial asthma, lesions of the endocrine glands, etc.). They play a leading role in the development of infectious and allergic diseases. (tuberculosis, leprosy, brucellosis, syphilis, etc.), transplant rejection.
The inclusion of a particular type of allergic reaction is determined by two main factors: properties of the antigen and the reactivity of the organism.
Among the properties of an antigen, its chemical nature, physical state and quantity play an important role. Weak antigens found in the environment in small quantities (plant pollen, house dust, dander and animal hair) often give an atopic type of allergic reactions. Insoluble antigens (bacteria, fungal spores, etc.) often lead to a delayed-type allergic reaction. Soluble allergens, especially in large quantities (antitoxic serums, gamma globulins, bacterial lysis products, etc.), usually cause an allergic reaction of the immunocomplex type.
Types of allergic reactions:
- Immune complex type of allergy (I I I type).
- Delayed type allergy (type IV).
Over the past two decades, the frequency of allergic diseases has increased significantly, especially in economically developed countries and in countries with an unfavorable environmental situation. Some scientists predict that the 21st century will be the century of allergic diseases. Currently, more than 20 thousand allergens are already known, and their number continues to grow. Various factors appear today as the reasons for the increase in the frequency of allergic diseases.
- 1. Change in the structure of infectious morbidity. At present, it is generally accepted that the function of T-lymphocytes-helpers of the 2nd type normally prevails in the human immune system at birth. This is due to the peculiarities of the immune mechanisms that regulate the relationship in the mother-fetus system during pregnancy. However, after birth, during the period of maturation of the immune system, there should normally be a change in orientation in the ratio of the function of T-lymphocytes-helpers in favor of strengthening the function of type 1 T-helpers. In this they are helped by viral and bacterial antigens, which, by activating macrophages, contribute to the production of interleukin 12 by the latter. In turn, IL-12, acting on type 0 T-helpers, shifts their differentiation towards type 1 T-helpers, which produce gamma-IFN and suppress the function of type 2 T-helpers. It may sound paradoxical, but today there is every reason to say that improving the quality of life, reducing the number of viral and bacterial diseases in childhood, including tuberculosis, leads to an increase in the function of type 2 T-helpers and the development of allergic reactions in the future. .
- 2. Hereditary factors. It has been established that the genetic predisposition to allergies is polygenic in nature and includes:
genetic control of the enhanced function of type 2 T-helpers for the production of IL-4 and IL-5;
genetic control of increased IgE production; c) genetic control of bronchial hyperreactivity.
3. Environmental factors. In recent years, it has been shown that exhaust gases, tobacco smoke, due to the content of obvious pollutants such as NO2, SO2, or NO, enhance the function of type 2 T-helpers and the production of IgE. In addition, by acting on epithelial cells of the airways, they contribute to their activation and production of pro-inflammatory cytokines (IL-8, alpha-ONF, IL-6), which, in turn, have a toxic effect on epithelial cells that contribute to the development of allergic inflammation.
Stages of a true allergic reaction:
The presence of primary contact of the body's immune system with an allergen (antigen);
The presence of a certain time interval for changing the reactivity of the development of the immune response, which in this context is understood as the occurrence of sensitization; ends with the formation of antibodies and/or cytotoxic sensitized T-lymphocytes;
The presence of repeated contact with the same (specific) allergen-antigen;
And, finally, the development of characteristic clinical manifestations, which are based on one or another effector immune mechanisms, which were mentioned in the general part of this book, i.e. an allergic reaction develops; action that causes damage.
Based on the above, today there are three stages of a true allergic reaction.
I. Immune stage - lasts from the moment of initial contact of the immune system with the allergen until the development of sensitization.
II.Patochemical stage - is activated by repeated contact of the immune system with a specific allergen and is characterized by the release of a large amount of biologically active substances.
III.Pathophysiological stage - characterized by a violation of the functioning of cells and tissues of the body up to their damage under the influence of biologically active substances released by the immune system during the pathochemical stage.
We can also talk about the existence of stage IV - clinical, which completes the pathophysiological and is its clinical manifestation.
Thus, it should be remembered that the immune system of the body, developing an immune response, implementing humoral and cellular reactions as protective reactions aimed at maintaining immune homeostasis, in some cases can cause damage to its own cells and tissues. Such reactions, according to the historical tradition, are called allergic, or hypersensitivity reactions. However, even in cases of development of damage, allergic reactions are also considered as protective, contributing to the localization of the allergen that has entered the body and its subsequent removal from the body.
Conventionally, all hypersensitivity reactions, depending on the duration of the period between the onset of contact of the sensitized organism with the antigen and the onset of external (clinical) manifestations of an allergic reaction, are divided into three types:
Allergic reactions of immediate type (hypersensitivity of immediate type - HHT) - develop within 15-20 minutes (or earlier).
Late (delayed) allergic reactions HNT - develop within 4-6 hours.
Delayed-type allergic reactions (delayed-type hypersensitivity - HRT) - develop within 48--72 hours.
The classification of hypersensitivity reactions according to Gell and Coombs (1964), which provides for four types, is currently most widely used. In recent years, this classification has been supplemented by type V. The mechanism of the hypersensitivity reaction of types I, II, III and V is based on the interaction of the antigen with antibodies; IV hypersensitivity reactions depend on the presence in the body of sensitized lymphocytes carrying structures on their surface that specifically recognize the antigen. Below is a description of the different types of hypersensitivity reactions.
I. Anaphylactic type of hypersensitivity reactions. It is caused by the formation of a special type of antibodies related to IgE and having a high affinity (affinity) for tissue basophils (mast cells) and peripheral blood basophils. These antibodies are also called homocytotropic because of their ability to be fixed to the cells of the same animal species from which they are obtained.
When an allergen first enters the body, it is captured by antigen-presenting cells (macrophages, B-lymphocytes, dendritic cells) and is digested (processed). As a result of digestion under the influence of lysosomal enzymes, a certain amount of peptides is formed from the allergen, which are loaded into the peptide-binding grooves of the molecules of the major histocompatibility complex, transported to the surface of antigen-presenting cells and presented for recognition by T-helper lymphocytes. For certain reasons, allergenic peptides are recognized by type 2 T-helpers, which, at the moment of recognition, are activated and begin to produce IL-4, IL-5, IL-3, and other cytokines.
Interleukin-4 performs two important functions:
Under the influence of IL-4 and subject to the presence of a costimulation signal in the form of contact between two molecules of CD40L and CD40, the B-lymphocyte turns into a plasma cell that produces mainly IgE;
Under the influence of IL-4, IL-3, the proliferation of both types of basophils increases and the number of receptors for the IgE Fc fragment increases on their surface.
Thus, at this stage of the immune response, a fundamental basis is laid that distinguishes an immediate-type allergic reaction from all other hypersensitivity reactions: specific IgE (homocytotropic antibodies, or reagins) are “produced” and fixed on tissue basophils and peripheral blood basophils.
Under the influence of IL-5, IL-3, eosinophils are also included in the “combat readiness”: their migratory activity and the ability to produce biologically active substances increase, their life span lengthens. On the surface of eosinophils, adhesion molecules appear in large numbers, allowing eosinophils to attach to the epithelium, in particular ICAM.
When a specific allergen enters the body again, it binds to IgE (moreover, it is very important that the allergen has a certain molecular weight that allows it to bind the Fab fragments of two adjacent IgE molecules located on the basophil (or mast cell) membrane), which leads to degranulation of basophils both types with the release of thrombocyte-activating factor, histamine, leukotrienes, prostaglandins, etc. The release of biologically active substances during degranulation leads to:
activation of platelets with the release of serotonin;
complement activation with the formation of anaphylotoxins - C3a and C5a, activation of hemostasis;
release of histamine and increased vascular permeability;
increased contraction of smooth (non-striated) muscle tissue under the influence of leukotrienes and prostaglandins (in particular, PGT2alpha).
All this ensures the development of the acute phase of the reaction, and its clinical symptoms, which are sneezing, bronchospasm, itching and lacrimation.
The mediators that are released during a type I allergic reaction are divided into reformed (i.e., already present in the granules of both types of basophils) and newly formed under the influence of phospholipase A2 during the breakdown of arachidonic acid cell membranes.
The participation of eosinophils in allergic reactions of the immediate type is characterized by two functions.
Mediators are released from eosinophils, which include the main basic protein of eosinophils, cationic proteins, peroxidase, neurotoxin, platelet-activating factor, leukotrienes, etc. Under the influence of these mediators, symptoms of the late phase develop, which are characterized by the development of cellular inflammation, destruction of the epithelium, hypersecretion of mucus, contraction of the bronchi .
Eosinophils produce a number of substances that help suppress the allergic reaction, reduce the consequences of its damaging power:
histaminase - destroying histamine;
arylsulfatase - contributing to the inactivation of leukotrienes;
phospholipase D - neutralizing platelet-activating factor;
prostaglandin E - reducing the release of histamine.
Thus, type I allergic reactions, like other immune reactions, have a dialectical character in terms of the realization of a protective potential, which can take on a damaging character. It's connected with:
release of mediators with destructive potential;
the release of mediators that destroy the function of the former.
At the first stage, the release of mediators leads to an increase in vascular permeability, promotes the release of Ig, complement into the tissues, enhances the chemotaxis of neutrophils, eosinophils. The inclusion of hemocoagulation mechanisms and the formation of blood clots in the microvascular bed localize the focus of penetration of the allergen into the body. All of the above leads to inactivation and elimination of the allergen.
At the second stage, the release of arylsulfatase, histaminase, phospholipase D, prostaglandin E2 contributes to the suppression of the function of mediators released at the first stage. The degree of clinical manifestations depends on the ratio of these mechanisms. In general, the pathophysiological stage of the T-type hypersensitivity reaction is characterized by:
increased permeability of the microvasculature:
the release of fluid from the vessels;
the development of edema;
serous inflammation;
increased formation of mucous excretions.
Clinically, this is manifested by bronchial asthma, rhinitis, conjunctivitis, urticaria, angioedema, angioedema, skin itching, diarrhea, an increase in the number of eosinophils in the blood and in secrets.
Concluding the review of type I allergic reactions, it should be noted that allergens that promote the production of IgE have a molecular weight in the range of 10-70 KD. Antigens (allergens) weighing less than 10 KD, if they are not polymerized, are not able to bind two IgE molecules on the surface of basophils and mast cells, and therefore are not able to “turn on” an allergic reaction. Antigens weighing more than 70 KD do not penetrate intact mucous membranes and therefore cannot bind to IgE present on cell surfaces.
II. Cytotoxic type of hypersensitivity reactions. It is realized in the same way as type I, by humoral antibodies, however, not IgE (as in type 1 reactions), but IgG (except IgG4) and IgM act as reactants. Antigens with which antibodies interact in type II allergic reactions can be both natural cellular structures (antigenic determinants), for example, when blood cells are damaged, and extracellular structures, for example, antigens of the basal membrane of the renal glomeruli. But in any case, these antigenic determinants must acquire autoantigenic properties.
The reasons for the acquisition of autoantigenic properties by cells can be:
conformational changes in cell antigens;
membrane damage and the appearance of new “hidden” antigens;
formation of an antigen + hapten complex.
As a result of the immune response, IgG and IgM are produced, which, by combining their F (ab) 2 fragments with cell antigens, form immune complexes. Under the influence of the formation of immune complexes, three mechanisms are activated:
Complement activation and implementation of complement-mediated cytotoxicity;
Activation of phagocytosis;
Activation of K-cells and realization of antibody-dependent cell-mediated cytotoxicity (ADCC).
During the pathochemical stage, complement activation is accompanied by opsonization. activation of inflammatory cell migration, increased phagocytosis, release of histamine under the influence of C3a, C5a, formation of kinins, destruction of the cell membrane. Activation of neutrophils, monocytes, eosinophils leads to the release of lysosomal enzymes from them, the formation of superoxide anion radical, singlet oxygen. All these substances are involved in the development of cell membrane damage, in the initiation and maintenance of free-radical lipid oxidation of cell membranes.
As clinical examples of type II allergic reactions, one can cite autoimmune hemolytic anemia, autoimmune thyroiditis, allergic drug agranulocytosis, thrombocytopenia, nephrotoxic nephritis, etc.
III. Immune complex type of hypersensitivity reactions. It is characterized in the same way as the cytotoxic type II by the participation of IgG and IgM. But unlike type II, here antibodies interact with soluble antigens, and not with antigens located on the surface of cells. As a result of the combination of antigen and antibody, a circulating immune complex is formed, which, when it is fixed in the microvasculature, leads to complement activation, release of lysosomal enzymes, formation of kinins, superoxide radicals, release of histamine, serotonin, endothelial damage and platelet aggregation with all subsequent events. leading to tissue damage. Examples of type III reactions are serum sickness, local reactions like the Arthus phenomenon, exogenous allergic alveolitis (farmer's lungs, pigeon breeders' lungs, etc.), glomerulonephritis, some variants of drug and food allergies, autoimmune pathology.
The pathological potential of immune complexes in type III allergic reactions is determined by the following factors:
- 1. The immune complex must be soluble, formed with a slight excess of antigen and have a molecular weight of -900-1000 KD;
- 2. The composition of the immune complex should include complement-activating IgG and IgM;
- 3. The immune complex must circulate for a long time, which is observed when:
prolonged intake of the antigen;
in violation of the excretion of immune complexes as a result of overload of the monocyte-macrophage system, blockade of Fc-, C3b- and C4b-receptors;
4. The permeability of the vascular wall should be enhanced, which occurs under the influence of:
vasoactive amines from both types of basophils and platelets;
lysosomal enzymes.
With this type of reaction, neutrophils predominate in the focus of inflammation, then macrophages, and finally lymphocytes.
IV. Delayed-type hypersensitivity reactions (cell-mediated or tuberculin hypersensitivity). This type of hypersensitivity is based on the interaction of a cytotoxic (sensitized) T-lymphocyte with a specific antigen, which leads to the release of a whole set of cytokines from the T-cell, mediating the manifestations of delayed hypersensitivity.
The cellular mechanism is activated when:
Insufficient efficiency of the humoral mechanism (for example, with the intracellular location of the pathogen - tubercle bacillus, brucella);
In the case when foreign cells act as an antigen (some bacteria, protozoa, fungi, transplanted cells and organs), or cells of one's own tissues, the antigens of which are changed (for example, the inclusion of an allergen-hapten in skin proteins and the development of contact dermatitis).
Thus, during the immunological stage, cytotoxic (sensitized) T-lymphocytes mature in the body.
During repeated contact with the antigen (allergen), in the pathochemical stage, cytotoxic (sensitized) T-lymphocytes secrete the following cytokines:
Macrophage migration inhibitory factor (MIF, MIF), which has the ability to enhance phagocytosis and is involved in the formation of granulomas;
Factor stimulating the formation of endogenous pyrogens (IL-1);
Mitogenic (growth) factors (IL-2, IL-3, IL-6, etc.);
Chemotactic factors for each white cell line, especially IL-8;
Granulocyte-monocytic colony-stimulating factors;
Lymphotoxins;
Tumor-necrotizing factor;
Interferons (alpha, beta, gamma).
Cytokines released from sensitized T-lymphocytes activate and attract cells of the monocyte-macrophage series to the focus of inflammation.
In the event that the action of lymphocytes is directed against viruses that infect cells, or against transplantation antigens, stimulated T-lymphocytes are transformed into cells that have the properties of killer cells in relation to target cells that carry this antigen. These reactions include: allergies that form in some infectious diseases, transplant rejection, some types of autoimmune lesions.
Thus, during the pathophysiological stage, damage to cells and tissues occurs due to:
Direct cytotoxic action of T-lymphocytes;
Cytotoxic action of T-lymphocytes due to non-specific factors (pro-inflammatory cytokines, apoptosis, etc.);
Lysosomal enzymes and other cytotoxic substances (NO, oxidants) of activated cells of the monocyte-macrophage series.
In type IV allergic reactions, among the cells infiltrating the focus of inflammation, macrophages predominate, then T-lymphocytes, and, lastly, neutrophils.
An example of delayed-type hypersensitivity is allergic contact dermatitis, allograft rejection, tuberculosis, leprosy, brucellosis, fungal infections, protozoal infections, and some autoimmune diseases.
V. Stimulating type of hypersensitivity reactions. When reactions of this type are implemented, cell damage does not occur, but, on the contrary, cell function is activated. A feature of these reactions is that they involve antibodies that do not have complement-fixing activity. If such antibodies are directed against the components of the cell surface involved in the physiological activation of the cell, for example, against the receptors of physiological mediators, then they will cause stimulation of this cell type. For example, the interaction of antibodies with antigenic determinants that are part of the structure of the thyroid-stimulating hormone receptor leads to a reaction similar to the action of the hormone itself: to the stimulation of thyroid cells and the production of thyroid hormone. In fact, such antibodies are referred to as autoimmune antibodies. This immune mechanism underlies the development of Graves' disease - diffuse toxic goiter. The considered classification of hypersensitivity reactions, despite the fact that it was proposed more than 30 years ago, allows you to get a general idea of the types of immunologically mediated reactions affecting cells and tissues; allows you to understand the fundamental differences in the mechanisms underlying them, as well as in the basis of clinical manifestations; and, at last, allows to explain possible ways of medical control over the course of these reactions.
It is important to take into account that, as a rule, not one, but several types of hypersensitivity reactions are involved in the mechanisms of development of individual nosological forms.
ALLERGY. MAIN TYPES OF ALLERGIC REACTIONS, MECHANISMS OF THEIR DEVELOPMENT, CLINICAL MANIFESTATIONS. GENERAL PRINCIPLES OF DIAGNOSTICS, TREATMENT AND PREVENTION OF ALLERGIC DISEASES.
Exists special type response to an antigen immune mechanisms. This unusual, different form of response to an antigen, which is usually accompanied by pathological reaction, called allergies.
The concept of "allergy" was first introduced by the French scientist C. Pirquet (1906), who understood allergy as modified sensitivity (both increased and decreased) of the body to a foreign substance upon repeated contact with this substance.
Currently in clinical medicine allergies understand the specific hypersensitivity (hypersensitivity) to antigens - allergens, accompanied by damage to their own tissues when the allergen enters the body again.
An allergic reaction is an intense inflammatory reaction in response to safe for the body of the substance and in safe doses.
Substances of an antigenic nature that cause allergies are called allergens.
TYPES OF ALLERGENS.
There are endo- and exoallergens.
Endoallergens or autoallergens are formed within the body and can be primary And secondary.
Primary autoallergens - these are tissues separated from the immune system by biological barriers, and immunological reactions leading to damage to these tissues develop only when these barriers are violated . These include the lens, the thyroid gland, some elements of the nervous tissue, and the genital organs. In healthy people, such reactions to the action of these allergens do not develop.
Secondary endoallergens are formed in the body from its own damaged proteins under the influence of adverse factors (burns, frostbite, trauma, the action of drugs, microbes and their toxins).
Exoallergens enter the body from the external environment. They are divided into 2 groups: 1) infectious (fungi, bacteria, viruses); 2) non-infectious: epidermal (hair, dandruff, wool), medicinal (penicillin and other antibiotics), chemical (formalin, benzene), food (, vegetable (pollen).
Routes of exposure to allergens varied:
- through the mucous membranes of the respiratory tract;
- through the mucous membranes of the gastrointestinal tract;
- through the skin
- by injection (allergens enter directly into the bloodstream).
Conditions necessary for an allergy to occur :
1. Development of sensitization(hypersensitivity) of the body to a certain type of allergen in response to the initial introduction of this allergen, which is accompanied by the production of specific antibodies or immune T-lymphocytes.
2. Re-hit the same allergen, resulting in an allergic reaction - a disease with corresponding symptoms.
Allergic reactions are strictly individual. For the occurrence of allergies, hereditary predisposition, the functional state of the central nervous system, the state of the autonomic nervous system, endocrine glands, liver, etc. are important.
Types of allergic reactions.
By mechanism development and clinical manifestations There are 2 types of allergic reactions: immediate hypersensitivity (GNT) And delayed hypersensitivity (HRT).
GNT associated with the production antibodies - Ig E, Ig G, Ig M (humoral response), is B-dependent. It develops a few minutes or hours after the repeated introduction of the allergen: the vessels dilate, their permeability increases, itching, bronchospasm, rash, and swelling develop. HRT due to cellular reactions cellular response) - the interaction of an antigen (allergen) with macrophages and T H 1-lymphocytes, is T-dependent. It develops 1-3 days after the repeated introduction of the allergen: there is a thickening and inflammation of the tissue, as a result of its infiltration by T-lymphocytes and macrophages.
Currently adhere to the classification of allergic reactions according to Gell and Coombs,
highlighting 5 types by the nature and place of interaction of the allergen with the effectors of the immune system:
I type- anaphylactic reactions;
II type- cytotoxic reactions;
III type- immunocomplex reactions;
IV type- Delayed type hypersensitivity.
I, II, III types hypersensitivity (according to Gell and Coombs) refer to GNT. IV type- To HRT. Antireceptor reactions are distinguished into a separate type.
Type I hypersensitivity - anaphylactic, in which the primary intake of the allergen causes the production of IgE and IgG4 by plasma cells.
Development mechanism.
On initial admission the allergen is processed by antigen-presenting cells and exposed to their surface together with MHC class II to present T H 2. After the interaction of T H 2 and B-lymphocyte, the process of antibody formation (sensitization - the synthesis and accumulation of specific antibodies). Synthesized Ig E are attached by the Fc fragment to receptors on basophils and mast cells of the mucous membranes and connective tissue.
On secondary admission The development of an allergic reaction proceeds in 3 phases:
1) immunological- the interaction of existing Ig E, which are fixed on the surface of mast cells with the re-introduced allergen; at the same time, a specific antibody + allergen complex is formed on mast cells and basophils;
2) pathochemical- under the influence of a specific antibody + allergen complex, degranulation of mast cells and basophils occurs; a large number of mediators (histamine, heparin, leukotrienes, prostaglandins, interleukins) are released from the granules of these cells into the tissues;
3) pathophysiological- there is a violation of the functions of organs and systems under the influence of mediators, which is manifested by the clinical picture of allergy; chemotactic factors attract neutrophils, eosinophils and macrophages: eosinophils secrete enzymes, proteins that damage the epithelium, platelets also secrete allergy mediators (serotonin). As a result, smooth muscles contract, vascular permeability and mucus secretion increase, swelling and itching appear.
The dose of antigen that causes sensitization is called sensitizing. It is usually very small, because large doses may cause not sensitization, but the development of immune protection. The dose of antigen administered to an animal already sensitized to it and causing the manifestation of anaphylaxis is called permissive. The resolving dose should be significantly greater than the sensitizing dose.
Clinical manifestations: anaphylactic shock, food and drug idiosyncrasy, atopic diseases:allergic dermatitis (urticaria), allergic rhinitis, pollinosis (hay fever), bronchial asthma.
Anaphylactic shock in humans, it occurs most often with repeated administration of immune foreign sera or antibiotics. Main symptoms: pallor, shortness of breath, rapid pulse, a critical decrease in blood pressure, shortness of breath, cold extremities, swelling, rash, decrease in body temperature, CNS damage (convulsions, loss of consciousness). In the absence of adequate medical care, the outcome can be fatal.
For prevention and prevention anaphylactic shock, the desensitization method according to Bezredko is used (was first proposed by the Russian scientist A. Bezredka, 1907). Principle: the introduction of small permissive doses of the antigen, which bind and remove part of the antibodies from circulation. The way is in the fact that a person who has previously received any antigenic drug (vaccine, serum, antibiotics, blood products), upon repeated administration (if he has hypersensitivity to the drug), is first injected with a small dose (0.01; 0.1 ml ), and then, after 1-1.5 hours - the main dose. This technique is used in all clinics to avoid the development of anaphylactic shock. This admission is mandatory.
With food idiosyncrasy allergies often occur on berries, fruits, spices, eggs, fish, chocolate, vegetables, etc. Clinical symptoms: nausea, vomiting, abdominal pain, frequent loose stools, swelling of the skin, mucous membranes, rash, itching.
Drug idiosyncrasy is hypersensitivity to repeated drug administration. More often it occurs to widely used drugs during repeated courses of treatment. Clinically, it can manifest itself in mild forms in the form of a rash, rhinitis, systemic lesions (liver, kidneys, joints, central nervous system), anaphylactic shock, and laryngeal edema.
Bronchial asthma accompanied severe attacks of suffocation due to spasm of the smooth muscles of the bronchi. Increased secretion of mucus in the bronchi. Allergens can be any, but enter the body through the respiratory tract.
Pollinosis - allergy to plant pollen. Clinical symptoms: swelling of the nasal mucosa and shortness of breath, runny nose, sneezing, hyperemia of the conjunctiva of the eyes, lacrimation.
Allergic dermatitis characterized by the formation on the skin of rashes in the form of blisters - bandless edematous elements of a bright pink color, rising above the level of the skin, of various diameters, accompanied by severe itching. Rashes disappear without a trace after a short period of time.
Available genetic predisposition To atopy- increased production of Ig E to the allergen, an increased number of Fc receptors for these antibodies on mast cells, increased permeability of tissue barriers.
For treatment atopic diseases are used desensitization principle - repeated introduction of the antigen that caused the sensitization. For prevention - identification of the allergen and exclusion of contact with it.
Type II hypersensitivity - cytotoxic (cytolytic). Associated with the formation of antibodies to surface structures ( endoallergens) own blood cells and tissues (liver, kidneys, heart, brain). It is caused by antibodies of the IgG class, to a lesser extent by IgM and complement. The reaction time is minutes or hours.
MECHANISM OF DEVELOPMENT. The antigen located on the cell is "recognized" by antibodies of the IgG, IgM classes. In the cell-antigen-antibody interaction, complement is activated and destruction cells by 3 destinations: 1) complement dependent cytolysis ; 2) phagocytosis ; 3) antibody-dependent cellular cytotoxicity .
Complement mediated cytolysis: antibodies are attached to antigens on the cell surface, a complement is attached to the Fc fragment of antibodies, which is activated with the formation of MAC and cytolysis occurs.
Phagocytosis: phagocytes engulf and (or) destroy target cells opsonized by antibodies and complement containing the antigen.
Antibody-dependent cellular cytotoxicity: lysis of target cells opsonized by antibodies using NK cells. NK cells attach to the Fc portion of antibodies that have bound to antigens on target cells. Target cells are destroyed by perforins and NK cell granzymes.
Activated complement fragments involved in cytotoxic reactions ( C3a, C5a) are called anaphylatoxins. They, like IgE, release histamine from mast cells and basophils, with all the corresponding consequences.
CLINICAL MANIFESTATIONS - Autoimmune Diseases due to the appearance autoantibodies to self-tissue antigens. Autoimmune hemolytic anemia due to antibodies to the Rh factor of erythrocytes; RBCs are destroyed by complement activation and phagocytosis. Pemphigus vulgaris (in the form of blisters on the skin and mucous membranes) - autoantibodies against intercellular adhesion molecules. Goodpasture's syndrome (nephritis and hemorrhages in the lungs) - autoantibodies against the basement membrane of the glomerular capillaries and alveoli. Malignant myasthenia gravis - autoantibodies against acetylcholine receptors on muscle cells. Antibodies block the binding of acetylcholine to receptors, leading to muscle weakness. autoimmune thyroidism - antibodies to thyroid-stimulating hormone receptors. By binding to receptors, they mimic the action of the hormone, stimulating the function of the thyroid gland.
type III hypersensitivity- immunocomplex. Based on education soluble immune complexes (antigen-antibody and complement) with the participation of IgG, less often IgM.
Picks: C5a, C4a, C3a complement components.
MECHANISM OF DEVELOPMENT. The formation of immune complexes in the body ((antigen-antibody) is a physiological reaction. Normally, they are quickly phagocytosed and destroyed. Under certain conditions: 1) the rate of formation exceeds the rate of elimination from the body; 2) with complement deficiency; 3) with a defect in the phagocytic system - the resulting immune complexes are deposited on the walls of blood vessels, basement membranes, i.e. structures with Fc receptors. Immune complexes cause activation of cells (platelets, neutrophils), blood plasma components (complement, blood coagulation system). Cytokines are involved, and macrophages are involved in the process in the later stages. The reaction develops 3-10 hours after exposure to the antigen. An antigen can be exogenous or endogenous in nature. The reaction can be general (serum sickness) or involve individual organs and tissues: skin, kidneys, lungs, liver. It can be caused by many microorganisms.
CLINICAL MANIFESTATIONS:
1) diseases caused exogenous allergens: serum sickness (caused by protein antigens), Arthus phenomenon ;
2) diseases caused endogenous allergens: systemic lupus erythematosus, rheumatoid arthritis, hepatitis;
3) infectious diseases accompanied by active formation of immune complexes - chronic bacterial, viral, fungal and protozoal infections;
4) tumors with the formation of immune complexes.
Prevention - exclusion or restriction of contact with the antigen. Treatment - anti-inflammatory drugs and corticosteroids.
Serum sickness - develops with a single parenteral administration large doses of serum and others protein drugs (for example, tetanus toxoid horse serum). Mechanism: after 6-7 days, antibodies appear in the blood against horse protein , which, interacting with this antigen, form immune complexes deposited in the walls of blood vessels and tissues.
Clinically serum sickness is manifested by swelling of the skin, mucous membranes, fever, swelling of the joints, rash and itching of the skin, a change in the blood - an increase in ESR, leukocytosis. The timing of manifestation and the severity of serum sickness depend on the content of circulating antibodies and the dose of the drug.
Prevention serum sickness is carried out according to the Bezredki method.
Type IV hypersensitivity - delayed-type hypersensitivity (DTH), caused by macrophages and T H 1-lymphocytes, which are responsible for stimulation cellular immunity.
MECHANISM OF DEVELOPMENT. HRT is called CD4+ T-lymphocytes(subpopulation Tn1) and CD8+ T-lymphocytes, which secrete cytokines (interferon γ), activating macrophages and induce inflammation(via tumor necrosis factor). macrophages are involved in the process of destruction of the antigen that caused sensitization. In some CD8+ disorders, cytotoxic T lymphocytes directly kill the target cell carrying the MHC I + allergen complexes. HRT develops mainly through 1 – 3 days after repeated allergen exposure. going on thickening and inflammation of the tissue, as a result of it infiltration by T-lymphocytes and macrophages.
Thus, after the initial ingestion of the allergen in the body, a clone of sensitized T-lymphocytes is formed, carrying specific recognition receptors for this allergen. At re-hit the same allergen, T-lymphocytes interact with it, are activated and secrete cytokines. They cause chemotaxis to the site of allergen injection. macrophages and activate them. macrophages in turn, they secrete many biologically active compounds that cause inflammation And destroy allergen.
With HRT tissue damage happens as a result of products activated macrophages: hydrolytic enzymes, reactive oxygen species, nitric oxide, pro-inflammatory cytokines.Morphological picture wearing HRT inflammatory character, caused by the reaction of lymphocytes and macrophages to the resulting allergen complex with sensitized T-lymphocytes. To develop such changes a certain number of T cells are needed, for what need 24-72 hours , and so the reaction called slow. At chronic HRT often formed fibrosis(as a result of the secretion of cytokines and macrophage growth factors).
DTH reactions may cause the following antigens:
1) microbial antigens;
2) helminth antigens;
3) natural and artificially synthesized haptens (drugs, dyes);
4) some proteins.
HRT is most pronounced on admission low-immune antigens (polysaccharides, low molecular weight peptides) when administered intradermally.
Many autoimmune diseases are the result of HRT. For example, when type I diabetes around the islets of Langerhans, infiltrates of lymphocytes and macrophages are formed; destruction of insulin-producing β-cells occurs, which leads to insulin deficiency.
Drugs, cosmetics, low molecular weight substances (haptens) can combine with tissue proteins, forming a complex antigen with the development contact allergy.
infectious diseases(brucellosis, tularemia, tuberculosis, leprosy, toxoplasmosis, many mycoses) accompanied by the development of HRT - infectious allergy .
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