Properties of anti-idiotypic T cell lines propagated with syngeneic B lymphocytes. I. T cells bind intact idiotypes and discriminate between the somatic idiotypic variants in a manner similar to the anti-idiotopic antibodies.

We describe the development of T cell lines possessing a binding specificity for syngeneic T15 idiotopes (Id) expressed on phosphorylcholine (PC)-reactive Ig. The lines were obtained by cultivation of BALB/c splenic T cells with T15 Id+ stimulator cells BCg3R-1d, a BALB/c lymphoma transfected with genomic sequences mu and kappa with S107 (T15) variable regions. Resulting Thyl-2+, L3T4+ cell lines depend on the T15 Id+ BCg3R-1d cells for growth and demonstrate the ability to bind TEPC15, a S107 germline-encoded, PC-specific Ig alpha. The specificity of the 125I-TEPC15 binding was studied in a competitive RIA with various unlabeled Ig. The isolated H and L chains of TEPC15 failed to inhibit the 125I-TEPC15 binding, and the T15-, PC-binding proteins M603 (alpha) and M511 (alpha) inhibited the binding either poorly or not at all. Moreover, the T cell lines had a discriminatory binding specificity for various T15+ Ig that are somatic variants of TEPC15 and that differ from each other in discrete, conformational Id (epitopes) detectable with specific monoclonal anti-Id. The T cell lines could be grouped according to their binding patterns, which were comparable to the recognition patterns of certain monoclonal anti-Id. These data suggest the existence of T cells with specificity for serologically-defined determinants of syngeneic idiotypes.