T-cell idiotypes are linked to immunoglobulin heavy chain genes.

FOUR gene clusters have products that seem to participate in antigen binding on T or B lymphocytes. Three (the genes coding for the heavy and light chains of immunoglobulin molecules) are known to code for structural elements of B-cell receptors for antigen. There is evidence that a fourth group (the immune response genes associated with the major histocompatibility complex (MHC) locus) generates T-cell recognition structures for antigen1. No evidence exists that any of these four gene groups are linked. In a study of the T-cell receptors for antigen we used anti-idiotypic antibodies against specific T-cell receptors2: T and B cells specific for the same antigen were shown to express similar idiotypes2. Analogous findings using other systems and approaches have been reported3,4. Together these results strongly suggest that antigen-binding receptors on T and B lymphocytes at least in part make use of the same genetic material. Accordingly, T-cell receptors should at least partly be coded for by genes linked to “conventional” immunoglobulin gene groups. We prove here that idiotypic T-cell receptors with specificity for MHC antigens in the rat are coded for by genes linked to the heavy chain immunoglobulin genes.