SPECIFIC SENSITIZATION TO DERMATOPHAGOIDES-PTERONYSSINUS AND CUTANEOUS REACTIVITY TO HISTAMINE IN BRAZILIAN CHILDREN

The immediate hypersensitivity cutaneous test is a recognized method f or etiologic diagnosis of allergic diseases. It is easily conducted, p ainless and can be quickly interpreted, making it ideal for use with c hildren. However, its low positivity in infants limits its use with th is population. The purpose of our study was to evaluate the skin react ivity of atopic and non-atopic children of different ages to increasin g concentrations of histamine and to an extract of Dermatophagoides pt eronyssinus (Dpt). Atopic children (A, n = 217) and non-atopic childre n (C, n = 198), under 15 years of age were grouped by age and administ ered skin prick tests. Increasing concentrations of histamine (1, 9, 8 1 and 243 mg/ml) and Dpt (10,000 AU/ml) were applied to the forearm. S kin reactions were recorded after 15 minutes and expressed as the mean of the largest wheal and ifs midpoint perpendicular diameter. Cutaneo us reactions were observed in the early phases of life with a progress ive increase observed in both groups. Significant differences were not ed between the two groups starting at 48 months of life. As the concen tration of histamine was increased, we observed a higher level of cuta neous reactivity in younger children. Comparative analysis of cutaneou s reactivity to the histamine solution (1 mg/ml) and the Dpt extract s howed parallelism between them and wheals with diameters larger than 3 mm after 12 months of age. We concluded that the skin prick test with Dpt is reliable in atopic children after 1 year of age. Reactivity to higher concentrations of histamine was observed after 3 months of age for all children. However, considering all age groups, the skin react ivity in atopic children to histamine (1 mg/ml) was more precocious wh en compared to controls.