PERIPHERAL CLONAL DELETION OF SUPERANTIGEN-REACTIVE T-CELLS IS ENHANCED BY CORTISONE

The T cell receptor (TcR) V(beta)-specific expansion, deletion and induction of nonresponsiveness among murine T cells responding to superantigens in the periphery has been welt characterized. Here we demonstrate that clonal deletion of staphylococcal enterotoxin (SE) B-reactive V(beta) 8.2+ cells can be significantly increased when mice are injected with hydrocortisone (HC) following superantigen stimulation in vivo. The induced sensitivity to HC persists for at least 30 days after SEB injection, making it unlikely that proliferating cells were uniquely responsible for the enhanced deletion. Superantigen-induced HC sensitivity was a general phenomenon and could also be observed among V(beta) 11+ cells after the injection of SEA. Experiments conducted on thymectomized mice indicated that HC-sensitive, SEB-responsive cells could not be accounted for by rapidly produced, immature lymphocytes recently exported from the thymus. Further V(beta) 8.1+ peripheral lymphocytes from TcR transgenic mice expressing the Mls-1a superantigen were sensitive to HC. These results imply that the majority of cells remaining after superantigen-induced clonal expansion and deletion in vivo have indeed reacted with the superantigen. Implications for differential superantigen recognition by T cells expressing the same TcR V(beta) domain, perhaps due to a significant V(alpha) contribution to the interaction in vivo, are discussed.