Allergy (types of allergies) – what is this condition, diagnostics, how to treat, prevention

Allergy – is a state of hypersensitivity, developing in response to repeated exposure to a specific allergen (antigen). Process, that occurs in the body after initial contact with the allergen, called allergization or sensitization.

Repeated exposure to the same allergen results in an inappropriately strong reaction (hypersensitivity) immune system, accompanied by damage to the body's own tissues. In this case, those tissues are damaged first of all., through which the allergen enters: skin, conjunctiva of the eye, mucous membranes of the respiratory and digestive organs. The result of such damage is the development of acute or chronic allergic diseases.. The term “allergy” itself was first proposed by the Austrian pediatrician Clemens von Pirke in 1906 year to characterize cases of excessive reactivity, which he observed in children with serum sickness, as well as infections.

Reasons for the development of allergies

Today, there are a number of risk factors, that contribute to the development of allergic diseases:

• heredity (if one of the parents has an allergy, the risk of developing it in a child is more than 30%, What if both parents have allergies? – more 70%);
• change in the structure of infectious diseases (improvement in quality of life and reduction in viral and bacterial infections in early childhood lead to the "reprogramming" of the immune system to develop hypersensitivity at an older age);
• environmental factors (traffic fumes, tobacco smoke, industrial pollution, inappropriate use of drugs, lack of breastfeeding in infancy).

Besides, rapid increase in the incidence of allergic diseases in advanced economies, provide the so-called "civilizational" factors. Modern products and things contain a large number of chemical additives and synthetic materials., which help to increase the permeability of natural biological barriers (skin and mucous membranes) for various substances-proteins in the first place. The immune system of the body perceives all these substances as foreign and reacts aggressively to them.

Types and properties of allergens

Allergens (antigens) name different chemical compounds, which are able to bind to the proteins of the human body and cause reactions of the immune system. How does the immune system react to certain substances?, with whom a person comes into contact during his life, can't predict exactly; for a sensitive organism, any of them can become an allergen. However, in most cases, protein compounds cause allergies.. In general, there are two large groups of allergens: infectious and non-infectious. The first group is represented by bacteria, viruses and fungi. The latter are the most common allergens; it is known 350 types of fungi, causing allergic reactions. Such fungi are found in the asthmasphere, house dust dwellings, spoiled products. Regarding bacteria and viruses, Allergization of the body is caused mainly by long-term, sluggish chronic infectious processes. Therefore, it is important to promptly diagnose and adequately treat any infections..

The group of non-infectious allergens is additionally classified depending on the way it enters the human body.: Household; food; epidermal; pollen; insect; Medicinal; industrial.

household allergens. House dust plays a major role among household allergens., which has a complex:

• dust particles from clothes, bed linen, pillows, blankets, mattresses, furniture upholstery;
• dust mites and their waste products;
• domestic insects and their metabolic products;
• fungi (in damp areas);
• bacteria.

Mites are the main allergens in house dust., that live in beds and feed on particles of human epidermis. In addition to house dust, household allergies are caused by warehouse mites and library dust., as well as dried daphnia, included in food for aquarium fish.

food allergens. In sensitive people, almost any product can cause allergies.. However, most allergens are protein products., cereals and some vegetables: fish, meat (especially pork), eggs, milk, chocolate, wheat, beans, tomatoes. Chemical substances also have pronounced allergenic properties., included in dietary supplements, which are used in the industrial production of products: antioxidants, Dyes, Flavors.

epidermal allergens. Represented by dandruff and animal hair, bird feathers, fish scales. Form an increased sensitivity of the body in humans, who, by virtue of their profession, have been in contact with this type of allergen for a long time: farm and vivarium workers, sheep breeders, horse breeders, groomers. Wool, the epidermis and feathers of pets are also a source of allergies for dog owners, cats, parrots and canaries.

Pollen allergens. Allergy caused by pollen from wind pollinated plants, which has certain properties: small size (less 35 m), spherical shape, lightness and volatility. This pollen is produced by 50 plant species, however, many of them share common allergens, that provoke similar allergic reactions in sensitive people. For Example, common allergens are the pollen of widely distributed cereal grasses: Rye, fescue, timothy, bluegrass.

insect allergens. The poison of stinging and saliva of biting insects has pronounced allergenic properties., as well as parts of their covers. Besides, same order and family of insects have similar allergens, therefore, sensitive people develop allergies to different types of insects.

Drug allergens. Any drug can cause an allergy., which, binding to human tissue proteins, becomes a complete allergen. At the same time, molecules of different drugs can have the same regions., which the immune system "recognizes" as foreign to the body. Therefore, if allergic to one drug, sensitive people will develop similar reactions to all other drugs., that have similar parts of the molecules.

Industrial allergens. Non-protein chemicals, like drugs, they become full-fledged allergens after they are combined with the proteins of the human body. The most significant industrial allergens are turpentine, oils, tar, resin, tannins, Dyes, arsenic, chrome, nickel.

Allergy types

Depending on the time of occurrence of the reaction of the body after contact with the allergen, All hypersensitivity reactions are conventionally divided into:

• immediate allergy. Develops over 15-20 m. (sometimes earlier)-to 1 Nights. Caused by the release of mediators from cells, affected by the allergen-antibody complex.
• delayed type allergy. Develops through 24-72 o'clock. Caused by the presence of specific immune cells in the body (sensitized lymphocytes), that can recognize a specific allergen.

Currently, the most widely used classification. Gella and R. Kumʙsa, proposed in 1969 year, according to which allocate 4 type of hypersensitivity (Table 1):

The mechanism of development of allergies

True allergic reactions ( regardless of the type) take place in 3 stage:

1. Immune (initial contact with the allergen, its recognition and development of sensitization with the formation of specific antibodies, mainly IgE immunoglobulins, rarely IgG and IgM);
2. pathochemical (upon repeated contact with the allergen, as a result of the work of immune mechanisms, a large number of biologically active substances-mediators are released);
3. pathophysiological (manifested by local and general reactions of body tissues to the action of mediators).

The pathophysiological stage ends with clinical manifestations of diseases, in which protective allergic antibodies in the composition of immune complexes “bombard” the cells and tissues of the body. Generally, the biological meaning of allergic reactions is the immune defense against foreign substances (antigens) by their localization or removal, even at the cost of self-harm of the body.

Allergic diseases

The classification of allergic diseases displays the forms of lesions of organs and systems, types of hypersensitivity, as well as the types of the most significant allergens.

Anaphylactic shock. This is a hyperacute generalized allergic reaction of the body., characterized by bronchospasm, a sharp decrease in systemic arterial pressure and a general severe course. Any allergen can cause an anaphylactic reaction., but most often the following:

• Medicines, predominantly protein (serum, Vaccine, preparations, which are used to diagnose allergies or treat specific allergies, enzymes and their inhibitors (trypsin, papain, contrycal, penicillinase), hormones (insulin, paratgormon), plasma). Non-protein drugs (antibiotics, antimicrobial substances, vitamins, non-protein hormones, radiopaque media) cause anaphylaxis less frequently.
• Food: primarily fish and seafood, rarely-nuts, eggs,milk.
• Insect bites.

The course of anaphylaxis is the more severe, the shorter the time elapsed between contact with the allergen and the onset of the clinical manifestations of the reaction. Therefore, the success of medical care in anaphylactic shock depends on the rate of stabilization of blood pressure and respiration.. Immediately stop contact with the allergen and carry out the full range of therapeutic measures. Full recovery is possible even with an extremely serious condition of the patient., Therefore, medical assistance must be provided quickly., insistently, in full.

Urticaria and angioedema. Typical allergic reaction, which develops mainly in diseases of the gastrointestinal tract, dysbacteriosis and helminthic invasions. Acute or chronic urticaria can also be caused by other factors. (low or high temperatures, medicines, change in autonomic regulation, pressure on or rubbing of skin). An external allergic reaction is manifested by a characteristic rash, caused by swelling of the papillary layer of the skin and similar to a burn nettle. With hives, the rash appears quickly and disappears just as quickly.. With the spread of the allergic process to the deep layers of the skin and subcutaneous tissue, Quincke's edema is formed. Treatment depends on the form and course of urticaria and / or Quincke's edema. Allergen avoidance is most effective, treatment of the underlying disease, antiallergic and symptomatic drugs.

Serum sickness develops in response to the introduction of foreign serum (blood products, immunoglobuliny) less often for other drugs (long-acting penicillins), Manifested by an inflammatory lesion of blood vessels and connective tissue on 7-12 the day after injection. Early manifestations - redness, swelling and itching at injection sites. Further join the manifestation communities: hives (90% patients), angioedema (much less often), papules; fever and joint pain (50% patients); inflammation (vasculitis) large vessels of the heart, light, pancreas. Serum sickness, usually, is of good quality; most symptoms disappear after 3-10 days after stopping the administration of the drug that caused it. Treatment: antiallergic, anti-inflammatory, symptomatic.

Bronchial asthma (BA). Chronic allergic respiratory disease, which is manifested by repeated bouts of shortness of breath, due to inflammation of the mucous membrane and narrowing of the bronchi, as well as increasing their sensitivity to any stimuli. Attacks of wheezing are also typical for AD., paroxysmal cough, feeling of tightness in the chest (especially at night or early morning). Bronchial constriction in asthma is reversible—spontaneous or with appropriate treatment. Since it is impossible to completely avoid contact with allergens in real life, Modern AD therapy is aimed primarily at achieving control of the disease itself.: treatment of allergic inflammation of the respiratory tract, prevention of recurrence and complications. For this, inhaled corticosteroids are used. (ICS), which, if necessary, are combined with other groups of drugs, depending on the type and variant of the course of asthma in a particular patient. well controlled (absence of exacerbations and complications) Asthma allows the patient to lead an active and high-quality lifestyle..

Nasal allergy (AP). I is the most common chronic allergic disease and is manifested by bouts of sneezing, itching in the nose and eyes, headache, copious watery discharge from the nose. According to the features of the current, seasonal and year-round AR are distinguished. The first option is characterized by bouts of sneezing and itching during the flowering period of plants. (late spring-summer), whose pollen causes allergic inflammation of the mucous membrane of the upper respiratory tract in sensitive people. Seasonal AR is also called hay fever.. Year-round AR worries the patient regardless of the season; bouts of sneezing and itching can occur in response to any allergen. Allergic rhinitis is often accompanied by conjunctivitis (inflammation of the mucous membrane of the eyes), and is also an independent risk factor for the development of bronchial asthma. According to the results of many studies, 30-40% patients with allergic rhinitis suffer from asthma, and in 80% people with asthma are diagnosed with allergic rhinitis. As with asthma, Modern treatment for allergic rhinitis focuses on around-the-clock symptom control: reduction of allergic inflammation of the nasal mucosa, prevent attacks. For this, ICS is used., which, if necessary, combined with other groups of drugs in each case.

Pollen disease (hay fever). FROMseasonal allergic disease, caused by hypersensitivity to pollen of plants during their flowering. Dry and windy weather contributes to the transport of allergenic pollen over long distances.. Besides, in cities pollen is more aggressive, because it adsorbs on itself particles of chemicals and exhaust gases. Plants, that produce allergenic pollen, differ in different regions of the world; to date, there are detailed flowering calendars, which make it possible for sensitive people to avoid contact with pollen allergens. Besides, with hay fever, it is necessary to take into account the presence of cross-allergy between some plants, herbal medicines and foodstuffs. Pollinosis is characterized by allergic inflammation of the mucous membranes of the eyes and respiratory tract.. Manifested by redness, swelling and itching of the conjunctiva, tearing, runny nose and cough. In this case, the patient's condition may be aggravated by other symptoms. (temperature rise, headache and joint pain, rash on the skin, digestive disorders). The most common rhinoconjunctival form of hay fever (nasal allergy, conjunctivitis) and pollen asthma. The first is manifested by itching in the eyes and nose, sneezing, nasal congestion, the second - bouts of shortness of breath. Pollinosis predominantly affects young people. Treatment of hay fever has a number of features. Since skin testing and allergen-specific therapy (ASIT) carried out only outside the exacerbation of hay fever, for 2-3 weeks before and during the entire flowering season, antiallergic drugs of various groups are used, that reduce inflammation and allergy symptoms. In severe hay fever, corticosteroids are used in the forms, contributing to the effective delivery of the drug to the affected target organ: eye drops, nasal sprays, metered dose inhalers. In addition to avoiding contact with established pollen allergens as much as possible, it is recommended to limit your stay outdoors in dry, hot and, especially, in windy weather; avoid trips and hikes in the forest, parks and fields; take a shower and change clothes when returning from a walk; clean your home more frequently; do not dry clothes outside.

Atopic dermatitis (FROM). Chronic allergic skin lesions, characterized by a relapsing course, which leads to a decrease in its protective and barrier function. External factors in the development of AD are most often food allergens and medications.. Clinically, AD is manifested by various elements of an allergic rash at different stages of development.: severe redness, weeping microbubbles, itchy papules, serous crusts. Persistent redness remains, dryness and flaking of the skin appear, it is possible to attach an infection with the formation of microbial eczema. The rash in AD is located on the flexion surfaces of the arms and legs, less often around the eyes, mouth, on the neck. Pruritus is a characteristic symptom of AD.. In young children, AD begins with redness and dryness of the cheeks., and in the folds of the skin (especially the perineum, buttocks) develop diaper rash that is difficult to treat. Treatment of allergic dermatitis begins with the elimination of the likely food allergen from the diet. (elimination diet), which is most effective in young children. In adolescents and adults, the elimination diet is practically ineffective., since the allergic process passes into a non-specific stage, at which the allergen loses its starting significance. In such cases, general nutrition correction helps., unloading diets and enterosorption. At the same time, they treat chronic infectious and inflammatory processes in the body, correction of metabolic disorders. To reduce inflammation and itching of the skin, anti-allergic and anti-inflammatory drugs are used in various dosage forms. (Creams, ointment, solutions, tablets). In the complex treatment of AD at all stages of the disease, local moisturizing dermatological emollient preparations are also used..

food allergy. In the development of food allergies may be involved as immunological, and non-immunological mechanisms. In the first case, they talk about a true food allergy., in the second, about pseudo-allergy or para-allergic reactions. Food allergy is an IgE-mediated reaction to the protein components of food.. Almost any product or its component can cause such a reaction, both independently, as well as various additives (other than glucose, sodium chloride and ethanol). The development of a true allergic reaction does not depend on the dose of the allergen. The most common cause of allergies is fish., seafood (crabs, shrimp), peanuts, milk, eggs, honey. Atopic dermatitis and allergic lesions of the gastrointestinal tract are more common in young children. (gastritis, enteritis, colitis). In adolescents and adults, allergic rhinitis, bronchial asthma. Severe communities of allergic reactions are much less common - anaphylactic shock or Quincke's edema.

Pseudoallergy (paraallergy, "false" allergy) or food intolerance. Looks like a food allergy, but does not have a first (immune) stages of development. pathochemical (isolation of mediators) and pathophysiological (local or general reactions) pass similarly to true food allergies. Pseudo-allergy is most often caused by products with a high content of biologically active substances. (histamine, histamine liberators), that directly affect blood cells, releasing mediators, provoking the development of local or general allergic reactions. Fermented cheeses and salami contain the most histamine.. Other products, containing histamine and histamine liberators: dry wines, pickled vegetables, canned food, pickled and smoked products, honey, Brewer's yeast, tomatoes, sour berries, citrus, pulse, spinach, chocolate, cocoa, hazelnuts). The development of pseudo-allergy depends on the dose of the allergen, that comes with food. Pseudo-allergic reactions occur mainly with enzyme deficiency (chronic inflammatory diseases of the gastrointestinal tract), as well as the effects of toxic substances in products (nutritional supplements, packaging components, salts of heavy metals during conservation). Besides, pseudoallergy is characterized by a dose-dependence. In children, it has a generally favorable course and to 2 years of life disappears on its own (formed enzyme systems of the gastrointestinal tract). If pseudo-allegia has developed in an adult, then, usually, it persists. Important to remember, that the allergenicity of many foods can be significantly reduced or eliminated by heat treatment during food preparation. And vice versa, slightly allergenic foods can become highly allergenic when consumed with spices, alcohol and sugar. Treatment for true or false food allergies is based on exclusion (elimination) allergens. It's easy to achieve, if we are not talking about staple foods or their basic components (milk, feel sick, oil). With pseudo-allergies, improvement often occurs with a decrease in the amount or heat treatment of products., allergenic, exclusion from the diet of spices, alcohol, sweets and caffeine, as well as in the treatment of chronic inflammatory diseases of the gastrointestinal tract. For true allergies, especially severe, products should be excluded from the diet as much as possible for life, causing a reaction. Specific hyposensitization is ineffective.

insect allergy. Evolves into bites, ingestion of poison when stinging, as well as inhalation or contact with the skin of particles of integument or excrement of insects. The most common reactions to hymenoptera venom (honey bee). Reactions to bee stings are of a mixed allergic-toxic nature., arise immediately, hold on for a long time, characterized by significant local changes (strong pain, redness, edema, sometimes-necrosis). A threat to life is the general reaction of the body to sting: swelling of the mucous membranes of the respiratory tract and anaphylactic shock. In contact with cockroaches or daphnia (in aquarium fish food) allergic rhinitis may develop, conjunctivitis, bronchospasm. Treatment of general and local insect reactions is carried out in the same way., as with other types of allergies. The imposition of a tourniquet and the suction of poison from the wound of the cogut affect only the toxic, but not the allergic component of the reaction. If the allergen is identified, effective specific hyposensitization. Of great importance is the prevention of bites and stings with the help of repellents., also taking appropriate precautions.

drug allergy. Today it remains one of the most common and serious types of allergic diseases.. Most medicines can provoke the development of true or pseudo-allergic reactions.. Many drugs also provoke group and cross allergic reactions due to the common chemical groups in the structure of various drugs.. The exception is substances, which are physiological components of the human body: glucose and sodium chloride. Manifestations of drug allergies depend on the time of their development.. Superacute and acute anaphylactic shock, angioedema, urticaria and drug-induced bronchial asthma. Subacute rash, drug fever, vascular purpura. Delayed course characteristic of drug dermatitis, serum sickness, kidney damage, liver, hearts, joints. At the same time, allergic damage to organs and systems develops several days or even weeks after taking medications and is often not associated with it.. If a drug allergy is suspected, it should be distinguished from other side effects of drugs or the toxic effects of drugs in their overdose., individual intolerance or misuse. A positive elimination test allows a drug allergy to be suspected. (disappearance of symptoms after discontinuation of the drug). With this type of allergy, provocative tests are not recommended due to the development of possible side effects., cross or group allergic reactions. Treatment of drug allergy consists in the rapid withdrawal and elimination of the drug from the body using various methods.. If the disease does not allow you to cancel a certain class of medications (antibiotics, etc.) they are replaced with drugs of a different group and chemical structure to avoid cross-reactions.

Other forms of allergies. Photodermatitis (solar dermatitis) is a common type of allergy to sunlight or ultraviolet radiation. A photoallergic reaction develops through 24-48 hours after sun exposure. The rash is localized mainly on open areas of the skin, sometimes spreads to areas of the body, covered by clothes. The elements of the rash are similar to itchy allergic dermatitis, in severe cases, blistering may occur on the skin. The rash gets worse after every sun exposure., characterized by flaking and thickening of the skin. In 5-10% people with photoallergies develop persistent reddening of the skin - solar erythema, that does not disappear for years, even without sun exposure. General and local treatment of solar dermatitis is carried out with the help of antiallergic drugs., prescribed by the doctor. In this case, it is necessary to limit the patient's exposure to the sun., cover the skin as much as possible, use sunscreen with a high protection factor

Diagnosis of allergic diseases performed by allergologists or immunologists. Diagnostic steps include:

1. detailed survey (allergic history) and examination of the patient;
2. general laboratory and instrumental examination;
3. specific allergy testing.

The main purpose of collecting an allergic history and a general examination of the patient is to establish the allergic nature of the disease.. During the laboratory and instrumental examination, the patient's condition is assessed and violations of the work of his organs and systems are revealed.. A specific examination is carried out in order to establish the type of allergy, type of disease and choice of treatment. Allergological diagnostics includes skin tests and provocative tests. There are a number of contraindications for an allergological examination.:

• acute phase of allergic and exacerbation of concomitant chronic disease;
• acute infections;
• blood disease, tumor;
• nervous and mental illnesses, convulsions;
• pregnancy, lactation, first days of the menstrual cycle;
• Age to 3 years;
• the period of treatment of an allergic disease with antihistamines, hormones, membrane stabilizers, bronholitikami;
• history of anaphylactic shock.

Principles of treatment of allergic diseases

Modern therapy of allergic diseases is based on the following principles.:

• allergen elimination;
• drug treatment;
• allergen-specific immunotherapy;
• patient education.

The main role is played elimination measures, during which it is necessary to exclude the patient's contact with the allergen as much as possible. Since in real life it is far from always possible to completely eliminate contact with allergens., necessary drug treatment, aimed at suppressing allergic reactions. To relieve allergy symptoms and prevent exacerbations, the doctor prescribes antihistamines. (loratadine, desloratadine (Erius), ketotifen, clemastine (Tavegil), xloropiramin (Suprastin). Desloratadine – representative of the latest generation of this group of drugs, and at its reception the drowsiness is the least expressed. It should be noted, that the last two drugs belong to an earlier generation of antihistamines, which have a pronounced side effect in the form of lethargy and drowsiness, and therefore cannot be accepted by persons, who drive cars. Into a drug therapy regimen to accelerate the relief of allergy symptoms (especially its manifestations on the skin) also includes sorbents (Activated carbon, Enterosgel). It is very important for the patient to follow medical recommendations for taking medications and consult a doctor in time if it is necessary to revise the treatment regimen. (pregnancy, travels, exacerbation of a chronic disease, etc.). Allergen-Specific Immunotherapy (ASIT) is the most effective method for the treatment of allergic diseases in the presence of a well-established allergen with an IgE-dependent reaction development mechanism. The essence of the method lies in the long (3-5 years) reintroduction (under the skin or under the tongue) gradually increasing doses of the allergen, to which the body is sensitized. The result of treatment is a decrease or cessation of the manifestations of the disease upon contact with the allergen., reduction in drug treatment, stopping the progression of a chronic allergic disease. Of great importance in preventing the exacerbation of an allergic disease and maintaining a high quality of life is patient education. There are special educational programs for this purpose., in which patients get acquainted with the causes and mechanisms of the development of allergic diseases, principles of their diagnosis, treatment and prevention, and also improve mutual understanding in the "doctor-patient" system.