Tolerance induction via antigen inhalation: isotype specificity, stability, and involvement of suppressor T cells.

Mice were exposed to aerosolized ovalbumin (OA) once weekly for 5 min on 6 occasions, prior to systemic challenge with soluble or alum-adsorbed (AH-OA) antigen. Mice challenged with AH-OA manifested profound IgE isotype-specific tolerance; those challenged with soluble OA initially manifested anamnestic IgE/IgG responses, but secondary intraperitoneal immunization 13 days later with soluble OA revealed IgE isotype-specific tolerance. The tolerized mice contained splenic suppressor T cells which inhibited IgE but not IgG responses in an adoptive transfer assay. Tolerance was still demonstrable in mice 6 months after the cessation of aerosol exposures. Exposure of low IgE responder rat strains to aerosolized OA tolerized for both IgE and IgG responses.