Immunoepidemiological study of atopic dermatitis in a sample of Baghdad population

Atopic dermatitis is a chronic disease with many miserable complications. In spite of the highest prevalence of this disease, mere issi enough data concerning it from different scopes, therefore, this uniqpe study was accomplished dealing with some clinico-epidemioiogical pattern of the disease in Iraqi patients with the general demographic data and various immunological investigations (eosinophil counts & total serum IgE). In addition, this case-control study was carried out to investigate the possible association of some human leukocyte antigens (HLA) with atopic dermatitis in Arab Iraqi people. The human leukocyte antigen system contains a number of closely linked genes whose products control a variety
of functions concerned with the regulation of immune response. A total of 121 Arab Iraqi patients who were diagnosed to have atopic dermatitis in four big hospitals in Baghdad were chosen for this purpose from September 2002 to March 2003. The disease was diagnosed clinically according to the United Kingdom refinement of Hanifin and Rajka's diagnostic criteria for atopic dermatitis, and the patients were subgrouped into mild, moderate and severe forms using Rajka and Leagland scoring system. A control group of 121 unrelated healthy nonatopic individuals (matched for age, sex, and ethnicity) was selected for the comparison. The demographic features of those patients were; 85.1% from urban areas of Baghdad; female: male ratio of 1.3:1; their ages ranged between 1-29 years (mean±SD for age 12.9 ±4.2 years). While the mean age of onset was 3.2± 1.9 years; the majority of patients (89.3%) had developed dermatitis before the age of 5 years. The rate of atopic dennatitis was significantly decreasing with age. But no significant role of gender on the age of onset. Breast feeding provided no protection and season of birth appeared to have no effect on the occurrence of atopic dermatitis. About half of the patients were with long duration of dennatitis, the over all mean duration of disease was 8+2 years. Out of 121 patients, 63 (52.1%) gave a history of recurrent attacks and about one third of the patients (40; 33%) had persistent atopic dermatitis with varying intensity. Severe cases were 30 forming 24.8% of all cases. There was a significant association between family history of atopy in parents and personal history of atopy with atopic dermatitis. In general, respiratory atopy and family history were found in 75.2% and 70.2% of patients respectively. The significant provocation factors for atopic dermatitis in the current study were soap sensitivity (90.9%); wool clothes (89.3%); sweating (75.2%). daily bathing (57%); recurrent skin infections (86.8%); climate and seasonal variation (82.6%); and emotional stress (73.6%). Animals contact and food allergy were unable to precipitate atopic dermatitis or give rise to exacerbations of the disease. The overall frequencies of clinical manifestations were: Itching (100%); followed by erythema (84.3%) and lichenification (55.4%). The main sites of predilection were face in infants (87.5%), antecubital folds in children (69%) and popliteal fossa in adults (63.6%). Xerosis was the most significant screening parameter for differentiation of atopic dermatitis. Additionally, two laboratory parameters were investigated for their association with atopic dermatitis. These were eosinophil counts and total serum IgE. The majority patients showed a significant increase in the mean eosinophil counts (83.5%) and geometric mean serum IgE (81.8%). The results also showed a significant direct correlation between severity of atopic dermatitis with both eosinophil counts and total serum IgE. There was also a significant association between personal and family history of atopy with cosinophii counts and serum IgE level. But no significant association with sex, age of the patients or duration of atopic dermatitis was evident. Seventy HLA antigens were detected by the Jymphocytotoxicity test, fifty three antigens were of class I and 17 antigens were of class II. An increase in the frequency of HLA-A3 and a significant decrease (P=0.0002, Pc= 0.0026) in the frequency of HLA-DR4 in patients was observed as compared to the healthy unrelated nonatopic controls. This altered frequenc} of DR4 as compared to the normal group may support the theon that immunological mechanisms play an essential role in the pathogenesis of the disease and interestingly DR4 may had a protective effect against development of atopic dermatitis (OR=0.32). It was concluded for the first time in Iraq, that of all 70 HLA antigens tested, only DR4 gave a significant negative association with atopic dermatitis especially with severe cases of the disease. Also, there was a significant correlation between eosinophil counts and total serum IgE with the severity of atopic dermatitis. Moreover, a significant correlation between eosinophil counts and total serum IgE was noted.