Relationship of food allergy and atopic dermatitis in children

Relevance. A food allergy is an adverse immune response to food. Proteins are most often the allergen. At the moment, there is no exact information on the prevalence and geography of food allergies in adults and children [4,7.9]. Although a number of serious epidemiological studies have been conducted on the prevalence of allergies in children, the true number of food allergy sufferers is not known. An estimated 11 to 26 million people in Europe suffer from food allergies. In the world there are 6 659 040 000 people, respectively, the number of patients with food allergies is approximately 220-520 million people [2,3,7,9,10]. This is a serious global problem. The results of studies by many authors indicate the presence in children with atopic dermatitis of aggravated heredity in relation to allergic diseases [4,5,11]. Approximately 80% of children with atopic dermatitis (AD) have a history of allergic diseases (food allergy, hay fever, bronchial asthma, recurrent allergic reactions in parents) [1,2,11]. Food sensitization involves, directly or indirectly, almost all organs and systems of the body. Localization and number of "shock organs" involved in the pathological process determines the clinical picture of the disease, which determines the variety of its clinical manifestations [1,2,6].

Clarification of the nature of food Allergy in children with atopic dermatitis is fundamental in the definition of a rational diet, the most important component of complex treatment of the disease.

Objective: to determine the frequency, risk factors of developing food allergies, particularly its etiological structure and immunological manifestations in children with AD.

Materials and research methods . The survey included 88 children with AD in age from 2 to 14 years (16% are children of pre-school age and 84% are children over 8 years old) who suffer from persistent flow of various chronic pathologies. Moreover, 25% were patients who turned directly to an allergist about their typical manifestations of allergy (dermatitis, bronchial asthma).The majority (75%) were patients who were treated in the somatic departments for the underlying disease or were registered by a pediatrician or narrowly specialized physicians (neurologist, rheumatologist, otolaryngologist). All children regularly (2-3 times a year) received planned therapy for the underlying disease. Criteria for inclusion of patients in the study - the duration of the disease is not less than 6 months; continuous relapsing course of the disease; frequency of exacerbations at least 1 time per month; short-lasting effect of classical therapy. Standard clinical and instrumental examination methods were used.

The diagnosis of food allergy was made on the basis of a comprehensive clinical and laboratory examination of patients, taking into account the allergological anamnesis data, the analysis of the food diary, the results of skin testing with allergies, elimination and provocation tests. Skin tests were carried out with the nutritional allergens of the company AOOT Biomed them. THEM. Mechnikov. According to the main clinical manifestations of the disease, 5 groups were singled out - 1st c. (n = 22) - patients with arthralgia, 2nd gr. (n = 20) cephalalgia, 3rd gr. (n = 18) - gastritis and / or gastroduodenitis, 4th gr. (n = 17) - nasal bleeding, 5th gr. (n = 11) - enuresis. The duration of the disease ranged from 6 months. up to 1 year - 17%, up to 2-3 years 35%, more than 3 years - 48% of cases. The frequency of diseases from weekly to daily was recorded in 59% of patients and most often in the group of patients suffering from cephalalgia (80%) and enuresis (75%). In 22% of patients, exacerbations occurred from 1 to 3 times a month; in 24%, exacerbations were irregular (associated with fatigue, hypothermia, meteorological conditions, etc.). In 45% of patients, a combination of the underlying disease with the skin (atopic dermatitis) or respiratory (bronchial asthma, allergic rhinitis) manifestations of allergy was noted.

Results and discussion . Analysis of the most common clinical manifestations of chronic pathology in children showed that in the structure of cephalgia, chronic headache was determined - 42%, headache with cerebral angiodystonia - 20%, vegetovascular dystonia - 18%, migraine - 13%, residual organically lesion of the central nervous system -6%; in the structure of arthralgia: arthralgia of unspecified etiology - 58%, arthralgia with reactive arthritis - 42%; in the structure of gastrointestinal manifestations, chronic gastritis with normal acidity - 63%, chronic gastroduodenitis with normal acidity - 31%, erosive gastroduodenitis - 6%. It is known that the main risk factors for the development of food allergies are aggravated atopic heredity and perinatal factors. A detailed study of the risk factors for the development of food allergy revealed that the possibility of allergic reactions to food products is almost equally affected by the burdened allergy and the pathological course of pregnancy (65% and 52%, respectively).

In addition to hereditary burdens, the development of food allergies requires sensitization of the body. In this regard, significant results are presented by the results of skin testing, which revealed in 84% of cases an increased sensitivity to food allergens. A characteristic feature of skin testing in all patients was the presence in the overwhelming majority of cases (90%) of a weakly positive degree of sensibilization. This, apparently, is one of the reasons for the lack of a clear relationship between taking the product and the appearance of complaints, in connection with which patients do not associate their suffering with food allergies. In the structure of the etiological factors of food sensitization, chicken eggs (80%), food grains (73%), meat (67%), cow milk (55%) citrus fruits (42%), fish (45%) are identified. Moreover, depending on the nosological form of the disease, the etiological structure of food sensitization has its own characteristics. Analyzing the structure of the etiological factors of food sensitization, it was found that in all forms of diseases, sensitization to the egg was practically the same frequency (from 78% to 86%). Sensitization to other food allergens occurred with varying frequency. So, most often sensitization was determined:                  -in patients with cephalalgia: cereals

(91%), egg (75%), milk (63%), meat (56%);                 -in patients with arthralgia:

egg (85%), cereals (70%), fish and meat (58%), milk (51%);        -in patients with nasal bleeding: meat (93%), citrus fruits, egg (75%), cereals (69%);        -in patients with enuresis: egg (82%), meat (64%), milk and cereals (55%);                  -in patients with gastritis: cereals, egg (78%), meat (69%).

• - Type I: positive skin test results for 20 minutes, early (within the first 2 hours) or delayed (from 2 to 6 hours) positive reactions during provocative tests.

• - Type II: the presence of elevated levels of total IgE and / or specific IgE / IgG antibodies in the blood.

• - Type III: delayed (from 6 to 12 hours) positive reactions during provocation tests, the presence of elevated levels of CIC and immunoglobulins M, G in serum.

  -Type IV: positive results of skin tests after 24.48.72 hours, slower (after 24.48.72 or more hours) positive reactions during provocative tests, elevated levels of immunoglobulins M, G in blood serum. Immediatetype hypersensitivity was found in 77% of patients, in 28% - immunocomplex, in 55% - delayed type of allergic response. Analysis of the obtained data allowed us to identify the features of the immune response within each clinical group.It has been established that in each group of patients types of allergic reactions are rarely seen in isolated form, since in most cases there is a combination of pathogenetic mechanisms of food allergy development (table).

Table 1.

Types of allergic reactions in patients with a typical manifestations of food allergies (%)

Note: * - p <0.001; ** - p <0.01 in horizontal rowso.

In patients with gastritis and enuresis of food etiology, it is statistically significantly more often (p <0.001) that type I of allergic reactions is recorded in comparison with patients of other groups. patients with arthralgia (p <0.01), enuresis (p <0.01) and gastritis, gastroduodenitis (p <0.001) are more common to type I and IV types and reactions. Patients with nasal bleeding and cephalgia do not have statistically significant differences in the prevalence of one or another type of immune response, since they have I, III, and IV types with almost the same frequency.

Findings. 1. The high frequency of food allergy detection (65%) among children with persistent course of various chronic pathologies indicates a variety of its clinical manifestations. The etiological structure of food allergies, depending on the nosology of the disease, has its own characteristics.

The detected changes in immunity indices indicate that various types of allergic reactions are involved in the development of food allergy, and in most cases a combination of pathogenetic mechanisms is noted.