Staphylococcal-enterotoxin-dependent cell-mediated cytotoxicity.

T cells equipped with sophisticated TCR and MHC recognition structures, an efficient cytokine communication network and lethal cytotoxic effector functions constitute one of the bulwarks of the mammalian immune system. However, infective agents have developed strategies to undermine T-cell immunity; for example, certain bacterial toxins serve as 'superantigens' by binding to preserved determinants on MHC class-II-encoded proteins and activating T cells expressing particular sequences of TCR V beta gene products. In this paper, Mikael Dohlsten and colleagues present evidence suggesting that these bacterial superantigens direct T cells to eradicate MHC class-II-expressing antigen-presenting cells, thus counteracting specific T-cell functions.