Regulation of asthma by intestinal parasites. Investigation of possible mechanisms.

The serum IgE levels of asthmatic subjects from Papua, New Guniea (PNG) were similar to those of corresponding control subjects but significantly higher than Caucasian asthmatics from Western Australia (AUS). Notwithstanding these differences in total IgE, the levels of IgE antibodies to D. pteronyssinus (RAST units) were similar in both asthmatic groups. The mite specific IgE antibody levels were independent of those to Ascaris and hookworm, suggesting that antigenic competition is not a factor of importance in sensitization to environmental allergens in the tropics. This study does not support the proposal that the low prevalence of allergic disease in tropical areas where parasitism is endemic is attributed to mast cell blockade through saturation of IgE receptors.