CDR1 T-CELL RECEPTOR BETA-CHAIN PEPTIDE INDUCES MAJOR HISTOCOMPATIBILITY COMPLEX CLASS II-RESTRICTED T-T CELL-INTERACTIONS

T-T cell interactions have been proposed in postulated network theorie s of immunoregulation and autoimmunity. Despite previous reports of pr otection induced by T-cell receptor (TcR)-derived peptides in experime ntal autoimmunity, no evidence for T-T cell interactions by direct rec ognition of processed TcRs on native T cells was obtained. Here we rep ort that immunization of rats with overlapping sets of peptides of the TcR alpha or beta chain allowed us to detect immunogenic TcR peptides . Remarkably enough, these TcR peptides appeared to cluster within the hypervariable complementarity-determining regions of the TcR. Immuniz ation of rats with these TcR peptides induced CD4(+) TcR peptide-speci fic T cells, which recognized both rDNA TcR proteins and the original, arthritogenic T cell in a major histocompatibility complex class II-r estricted way. These findings indicate that activated T cells can proc ess and present their own TcR in the context of major histocompatibili ty complex class II molecules and, furthermore, that such peptides can be recognized by TcR variable gene-specific T cells.