Suppression of IgE responses by passive antigen inhalation: dissociation of local (mucosal) and systemic immunity.

Animals from high- and low-IgE-responder rat strains were preexposed to antigen-containing aerosols of different droplet sizes, prior to parenteral antigenic challenge. Depending upon the type of aerosol employed, systemic immunological tolerance developed in high-IgE-responder animals in the IgE antibody class either with or without concomitant production of salivary IgA, indicating that the two antibody isotypes were under independent control, and further that IgA-mediated immune exclusion was not central to the development of tolerance in the IgE class. Low-IgE-responder rats exhibited biphasic salivary IgA responses during exposure, which could not be recalled by subsequent parenteral challenge, suggesting that secretory immunity in the respiratory tract may also be down regulated by repeated exposure to airborne antigens.