Humoral and cellular immune responses of atopic individuals in a tropical environment

In this study we compared immediate, intermediate and delayed skin test reactivity, total and specific serum IgE, IgG, A, M antibody and lymphocyte proliferative responses, between atopic and normal individuals in the tropical environment of Caracas, Venezuela (Lat. 10 degrees N). The allergenic extracts tested were prepared from house dust, mixed moulds and Aspergillus fumigatus. In lymphocyte stimulation the mitogen Concanavalin A was also employed, the cultures being supplemented with either autologous plasma, or a gamma globulin-depleted pool. The results revealed the association of immediate skin reactions with IgE antibody against house dust, and intermediate reactions with IgG, A, M antibody against moulds. No relation was, however, detected between delayed skin reactivity and in vitro lymphocyte transformation; skin reactions occurred at the highest frequency with moulds, while house dust provoked the strongest in vitro stimulation. Also, although the areas of positive delayed reactions were greatest in the atopic individuals, the lymphocyte proliferative responses were clearly highest in the normal subjects. The significance of the positivity of lymphocyte transformation tests in all of the study group, but lower reactivity in the atopics, is considered.