Interactions between staphylococcal superantigens and human T-cell clones are predominantly but not exclusively...

Staphylococcal exotoxins (SE) are potent mitogens for human and murine T cells. Extensive studies in mice have demonstrated strict correlations between T-cell responses to individual SE and TCR V beta expression. Studies examining the TCR V beta expression of SE-activated human peripheral blood T cells also suggest close correlations, whereas the data reported using human T-cell clones (TCC) are conflicting. We have determined the cDNA TCRB sequences of 52 different human TCC, expressing 35 different T-cell receptor V beta (TCRBV)-encoded sequences. The TCC were tested in proliferative assays using nine different SE. Most of these TCC express V beta s which have not been tested previously in studies examining interaction between TCC and SE. The SE stimulated a variable fraction (1/48-31/52) of the TCC. The ability of a given SE to stimulate TCC in many cases correlated with V beta expression, but several exceptions were found. With one possible exception, comparisons between deduced amino-acid sequences within the 'fourth hypervariable region' of the TCR beta chain and SE responsiveness did not reveal potential SE binding motifs. We conclude that the reactivity of T cells towards SE is governed mainly by their TCR V beta expression. However, the authors' results also suggest that the interaction between SE and human T cells may involve elements unidentified as yet which are in addition to the beta chain of the TCR.