Inhibition of secondary anti‐hapten responses with the hapten conjugated to type 3 pneumococcal polysaccharide

Abstract An injection of 2, 4‐dinitrophenyl (DNP)‐lysine conjugated to type 3 pneumococcal polysaccharide (DNP‐lysine‐SIII) markedly reduced the secondary IgG anti‐DNP antibody response of irradiated mice injected with primed cells and the homologous dinitrophenylatcd foreign protein used for priming. Serum antibody titers against the foreign protein, hemocyanin, were not affected and the injection of DNP‐lysine‐SIII could be delayed until the 3rd day, but not the 4th day, after injection of the primed cells and homologous antigen. In mice in which anti‐DNP antibody production was reduced by DNP‐lysine‐SIII, antibody isoelectric spectral analysis of residual antibody suggested that clones of antibody‐producing cells were eliminated entirely or escaped unaltered. Purified SIII is a persisting antigen which readily induces macroglobulin responses in mice and does not seem to stimulate T cells. The results suggest that antigenic determinants on such antigens gain access to B cells and suppress IgC antibody production.