| Abstract: | The relationship between the Fc region of trinitrophenylated (TNP)-immunoglobulins (Ig), and their ability to induce tolerance was examined. It was found that adult B cells responding to a T-independent (TI) antigen were tolerized by TNP11 human gamma globulin (HGG), but not by TNP10F(ab')2 fragments of HGG. Increasing the hapten density on the F(ab')2 fragments overcame their inability to induce tolerance. Thus, a TNP17-F(ab')2 was an effective tolerogen. Murine myeloma proteins of different IgG subclasses were similarly tested. A TNP12-IgG2a and a TNP11-IgG1 induced tolerance, whereas two TNP11-12-IgG3 did not. However, a more heavily haptenated TNP18-IgG3 was tolerogenic. These results suggest that lightly haptenated immunoglobulins depend upon Fc receptor binding to induce tolerance in adult B cells. Non-Fc receptor-binding carriers are not tolerogenic unless they are more heavily haptenated. Finally, T cell and macrophage depletion experiments suggest that the tolerogens act directly on the B cells. |
