Oral induction of the secretory antibody response by soluble and particulate antigens.

The ability of gastric intubation of a soluble or a particulate form of dinitrophenylated bovine gamma-globulin (DNP-BGG) to induce salivary IgA antibody was examined. Gastric intubation of the particulate form of the antigen tended to induce a greater response than did equivalent doses of the soluble form. However, systemic immunization with the soluble form of the antigen prior to gastric intubation of antigen increased the salivary IgA response. Prior systemic injection of the particulate form did not increase the salivary IgA response. Immunoreactivity of the particulate moiety of the particulate antigen did not seem to be a factor in the observed differences, since three different synthetic particulate antigens with identical hapten-protein moieties produced the same results (i.e. prior injection with the synthetic particulate antigens did not increase the salivary IgA response).