Interaction between superantigen and T-cell receptor Vβ element determines levels of superantigen-dependent cell-mediated cytotoxicity of CD8+ T cells in induction and effector phases

Specific superantigens activate different T-cell fractions with distinct TCR V beta elements in association with MHC class II molecules and also induce SDCC against MHC class II+ target cells. In the present study, to determine whether the responsiveness of each CD8(+) T-cell fraction expressing a different TCR V beta element is primarily determined by the TCR V beta, we compared the levels of proliferation and SDCC in V beta 3(+) and V beta 11(+) T cells upon stimulation with SEA. Upon stimulation with SEA(wt), the levels of proliferation were higher in V beta 3(+) T cells than in V beta 11(+) T cells. The levels of SDCC were also higher for the combination of V beta 3(+) T cells and SEA(wt) than for the combination of V beta 11(+) T cells and SEA(wt) during both the induction phase and the effector phase. In addition, upon stimulation with SEA(m), the levels of proliferation were higher in V beta 11(+) T cells than in V beta 3(+) T cells. And then, the levels of SDCC were also higher for the combination of V beta 11(+) T cells and SEA(m) than for the combination of V beta 3(+) T cells and SEA(m) during both the induction phase and the effector phase. These results suggest that the SAG-responsiveness of each CD8(+) T-cell fraction expressing a different TCR V beta element is primarily determined by the interaction between the TCR V beta element and the SAG.