The T cell repertoire may be biased in favor of MHC recognition.

The receptors of two T cell hybridomas that recognize class I and class II major histocompatibility complex (MHC) molecules, respectively, have been compared. In both cases these receptors are hybrid molecules formed as a result of cellular fusion. The receptors contain the same alpha chain, contributed by the tumor cell fusion partner, and related beta chains, contributed by the normal T cell component. Thus, surprisingly, the same alpha chain can contribute to recognition of class I and class II MHC molecules. Moreover, the finding that in two independent examples hybrid receptor molecules created randomly by in vitro cell fusion recognize MHC supports the theory that the T cell repertoire has an intrinsic affinity for MHC.