Function of idiotypic networks in vivo: immunisation with idiotype-bearing (Id1) antibody induces further production of Id1 antibody.

Injection of BALB/c mice with an anti-foot-and-mouth disease virus (FMDV) monoclonal antibody (mAb) apparently induced the idiotype network to produce more anti-FMDV (idiotype-bearing) antibody, as determined by hybridoma production. Anti-idiotype antibodies were also induced, detected by binding directly to the mAb used for the immunizations (the "immunising" antibody). Many of the anti-idiotype antibodies were directed against regions in or near the paratope of the immunising mAb, since they competed for the binding of the latter mAb to 146S antigen. The induced idiotype-bearing (anti-FMDV) antibodies also competed for the binding of the immunizing mAb to 146S antigen, demonstrating that both antibodies were of similar epitope specificity. Consequently, it would appear that an idiotype-bearing (Id1) antibody can induce the idiotypic networks to produce more Id1 antibody of the same specificity as that used for the initial stimulation, demonstrating the in vivo functioning of the idiotype network.