Mechanisms of idiotype suppression. V. Anti-idiotype antibody inhibits early B cell triggering induced by antigen

To investigate the relationship between antigen-mediated B cell commitment and induction of idiotype (id) suppression, anti-id antibody directed against the major id (TEPC-15 idiotype or T15id) of the anti-phosphorylcholine (PC) antibody was added at various time intervals to BALB/c spleen cell cultures stimulated with a T-independent PC antigen, R36a. The suppressive effect of anti-T15id antibody on the anti-PC response was rapidly decreased as addition of the antibody was delayed; when anti-T15id antibody was added 6 hr after the initiation of the cultures, only partial suppression was induced, whereas the addition of anti-id antibody after 24 hr did not result in significant suppression of the anti-PC response when compared with similar cultures treated with mock anti-id antibody. This acquisition of resistance to id suppression was completely inhibited by treatment with either sodium azide or colchicine, as well as at temperatures below 20°C. The induction of resistance to id suppression during the preincubation period was dependent on the presence of an immunogenic level of specific antigen. This antigen-mediated B cell commitment did not appear to require macrophages because preincubation of macrophages with antigen did not affect the sensitivity of the B cells to anti-id antibody. These results support the possibility that anti-id antibody inhibits early B cell triggering, which involves an energy-dependent, epitope-mediated, lateral mobility of antigen receptors possibly followed by repolymerization of microtubules.