Expansion/deletion of mature T cells exposed to endogenous superantigens in vivo.

Previous studies have shown that in thymectomized hosts exposure of mature T cells to Mlsa (mtv-7) Ag in vivo leads to specific tolerance and the disappearance of Mlsa-reactive V beta 6+ T cells after an initial phase of T cell expansion. To investigate the factors controlling postthymic elimination of mature T cells, we examined T cell responses to Mlsa and other endogenous superantigens in a number of different strain combinations. The results show that the extent of T cell expansion/deletion is influenced by various factors, including the H-2 haplotype of the host and the particular V beta studied. Collectively, the results suggest that the extent of elimination of mature T cells is variable and may be a function of high avidity interactions with APC.