ALLERGIC REACTIVITY OF CHILDREN OF DIFFERENT SOCIOECONOMIC LEVELS IN TROPICAL POPULATIONS

Widely variable prevalences of allergic diseases have been reported in tropical populations, and this has been suggested to be due to effect s of the nonspecific polyclonal stimulation of IgE synthesis caused by the helminthic infections that are endemic in these areas. Since 1980 , we have been evaluating the allergic reactivity of different socioec onomic sectors of the population of tropical Venezuela (lat. 2-12-degr ees-N), and in the present study analyze the overall results obtained in the laboratory evaluation of children (5-15 years of age) belonging to these groups. Children of medium-high socioeconomic level (M-HSEL) , who experience occasional helminthic infections, have moderately hig h total serum IgE levels, and have elevated skin test positivities and specific IgE levels against environmental allergens. Persons of low s ocioeconomic level, in the urban, and particularly rural situation exp erience frequent helminthic infection, and have highly elevated total serum IgE levels. In contrast to the M-HSEL, the majority of these chi ldren have detectable specific IgE antibody against a variety of inhal ant allergens, but relatively few have high levels, and their skin tes t positivity is also low. In these frequently parasitized persons, evi dence of saturation of mast cell Fcepsilon receptors was found by test s of passive sensitization. We propose, therefore, that helminthic par asites have a biphasic effect on allergic reactivity; occasional infec tions are stimulatory, via their nonspecific potentiation of IgE synth esis against environmental allergens, and frequent infections are supp ressive due to the widely polyclonal stimulation that they cause, resu lting in both diminished specific antibody production against any give n allergen and mast cell Fcepsilon receptor saturation.