Immunogenicity of a hapten-carrier conjugate taken up by peritoneal cells.

The present experiments have been performed in order to study the immunogenicity of antigen taken up by peritoneal macrophages using the hapten-carrier model and to investigate the role of macrophages in the antigenic competition between hapten and carrier moieties of the antigen molecule we have previously described. Guinea pigs were immunized with peritoneal cells collected from guinea pigs previously injected intraperitoneally with soluble or glutaraldehyde-polymerized hapten-carrier conjugates in Freund's incomplete adjuvant. Delayed hypersensitivity reactions to the carrier and anaphylactic reactions to both the hapten and the carrier were studied 14 and 16 days after immunization. After immunization with macrophage-associated hapten-carrier conjugate, delayed hypersensitivity reactions to the carrier were first detected in the absence of anaphylactic reactions which appeared later. The capabilities of macrophage-ingested antigen to induce delayed hypersensitivity reactions, but not anaphylaxis, decreased when increasing the incubation time of macrophages with antigen. The antigenic competition between hapten and carrier was confirmed to be a transient phenomenon occurring in the macrophage.