Suppression of allergic reactivity by intestinal helminths: susceptibility is a function of IgE responder phenotype.

Animals from two inbred rat strains, Brown Norway (BN) and WAG, expressing high and low-IgE-responder phenotype, respectively, were sensitized to ovalbumin (OV) while parasitized with the intestinal helminth Nippostrongylus brasiliensis (Nb). The animals were challenged intradermally and intravenously with OV, and the severity of their immediate hypersensitivity responses was compared to those of non-parasitized OV-immune controls. Nb infestation depressed hypersensitivity responses in the low-IgE-responder WAG rats, but was without effect in high-IgE-responder BNs.