Specific recognition of staphylococcal enterotoxin A by human T cells bearing receptors with the V_γ9 region

Abstract

T CELLS bearing the αβ receptor can specifically react with target cells coated with staphylococcal enterotoxin and expressing major histocompatibility complex class II molecules; these responses depend on which variable region (V) of the receptor's β-subunit is used^1–7. We have now examined whether a similar situation exists for human T cells bearing the _γδ receptor. We found that reactivity to staphylococcal enterotoxin A is strictly dependent on the presence of the V_γ9 variable region in the _γδ T-cell receptor (TCR). These cytotoxic responses required the expression of HLA class II molecules by the target cell and could be inhibited by anti-_γδTCR and by anti-HLA-class-II monoclonal antibodies. In contrast to αβTCR⁺ cell clones, no proliferate response of V_γ9⁺ T-cell clones towards stimulator cells coated with enterotoxin A was observed in vitro. These results indicate that the _γδTCR repertoire might be influenced by enterotoxin A produced during staphylococcal infections in vivo. This could provide a molecular basis for the observation that V_γ9⁺ T cells form the large majority of peripheral _γδTCR⁺ cells but only a small proportion of thymic _γδTCR⁺ cells.