Functional and biochemical evidence for the recognition of T cell receptors by monoclonal antibodies to an immunoglobulin idiotype.

Sharing of "idiotypes" by T and B cells with similar nominal specificities has been extensively reported in functional assays. The recent molecular characterization of T cell receptors has led to the suggestion that such idiotypic mimicries could result from "network" selection of available T cell repertoires. Alternatively, the validity of the conclusions taken from those functional assays could be questioned. We have now used an experimental system where recurrent expression of antibody idiotypes by T helper cells requires "learning" from the B cell/antibody compartment, and show here that the idiotypic determinants in question are indeed associated with T cell receptor molecules. A monoclonal antibody (F6(51)) directed to an idiotope of the TNP-binding BALB/c myeloma protein MOPC460 specifically inhibits antigen-dependent proliferation and helper activity of BALB/c anti-TNP-BALB/c helper T cells. The anti-idiotypic antibodies also induce IL-2 production by these helper cells and precipitate a surface molecule with characteristics of T cell receptor. We conclude that, in this particular system, T cell receptors and antibodies of similar nominal specificities share idiotypic determinants.