Substance P and IgE-Mediated Allergy II. Reduction of Rhesus IgE Antibody after Aerosol Exposure to Substance P and Allergen

Experiments were designed to evaluate the effect of aerosolized Substance P (SP) and ascaris antigen (A) on airway responses of rhesus monkeys that had IgE antibody against A. During the course of these experiments, a totally unplanned and unexpected observation was made: this was a decline in IgE antibody, as determined by quantitative end-point dilution titers, in the group of animals that had received aerosolized SP and A. Our experience with this species of primate over 2 decades had shown that IgE-mediated cutaneous reactivity persists in the monkeys (as in man) for years with little change. The decline in IgE antibody titers in monkeys occurred over a few weeks to months, was related to the aerosol exposure to SP and A, and has persisted with minimal to moderate rise in IgE antibody. Although these results had to be analyzed retrospectively, the changes were significant by statistical analysis. This serendipitous observation suggests a possible means of reducing IgE antibodies therapeutically in primates. A theory of why primates may develop IgE antibody to antigens absorbed through mucosal surfaces is proposed.