Evidence for the endogenous production of T cell receptors bearing idiotypic determinants.

Unprimed thymus-derived (T) cells from spleens of either conventional TEPC 15+ (T15+) BALB/c mice or neonatally suppressed T15- BALB/c mice were used to reconstitute neonatally suppressed T15- BALB/c nude mice and conventional T15+ BALB/c nude mice, respectively. In so doing, the idiotypes produced by phosphorycholine (PC)-specific bone marrow-derived (B) cells were dissociated from idiotypes putatively produced by PC-specific T cells. Subsequent to priming of the reconstituted BALB/c nude mice with either anti-T15 antisera or PC-MOPC 315, their splenic T cells were assessed for PC-specific helper activity and expression of the T15 idiotype. Our results indicate that expression of the T15 idiotype by T cells as determined by (a) the ability to prime PC-specific helper cells with anti-T15 antibodies, and (b) the ability to inhibit PC-specific helper function with anti-T15 antibodies, depended on the idiotype of the unprimed donor T cell source and not that of the B cells in the reconstituted recipients. We conclude that the idiotype-bearing T cell receptor specific for PC is not a passively adsorbed B cell product.