Evidence for a functional interaction between the β chain of major histocompatibility complex class II and the T cell receptor α chain during recognition of a bacterial superantigen

Abstract

Several studies have suggested that there is a direct interaction between the T cell receptor (TCR) and the major histocompatibility complex (MHC) molecule during T cell recognition of superantigen. To further investigate this possibility, we have analyzed T cell recognition of a bacterial superantigen, Staphylococcal enterotoxin B (SEB), presented by a series of mutant murine I-E(k) molecules in which residues of either the α or β chain predicted to interact with the TCR have been substituted. Individual T cell hybridomas gave distinct patterns of responsiveness to SEB presented by the I-Eβ(k) mutants that could not be attributed to differences in the binding of SEB to the mutants. This effect appeared to be dependent on the TCR-α chain because some of these hybridomas expressed identical TCR transgenic β chains. In contrast, none of the hybridomas gave distinct patterns of responsiveness to SEB presented by the I-Eα(k) mutants. Taken together, these observations support the idea that there is a functional interaction between the α chain of the TCR and the β chain of the MHC class II molecule. The data also support the idea that this interaction might enhance superantigen recognition in some cases.