Activation of murine T cells by staphylococcal enterotoxin E: Requirement of MHC class II molecules expressed on accessory cells and identification of Vβ sequence of T cell receptors in T cells reactive to the toxin

Abstract We investigated a mechanism leading to activation of murine T cells by Staphylococcal enterotoxin E (SEE). L cells transfected with I-A b genes but not control L cells supported IL-2 production by SEE-induced C57BL/6 T lymphoblasts upon restimulation with SEE. mAb to I-A b markedly inhibited the above response. Flow cytometric analyses showed that SEE-induced C57BL/6 T lymphoblasts are composed of both CD4 + T cells and CD8 + T cells, and that larger parts of them bore Vβ11 (40–75%). mAb to Vβ11 markedly inhibited the SEE-induced proliferative response and IL-2 production by T cells. Analysis of SEE-induced IL-2 production in spleen cells from various mouse strains showed that C57BL/6 and B10.A(4R) mice (I-E, not expressed; Vβ11 + T cells, normally generated) are highly responsive to SEE. In contrast, BALB/c, C3H/HeN, (C57BL/ 6 × BALB/c or C3H/HeN) F1 mice (I-E, normally expressed and Vβ11 + T cells, deleted), and SJL and C57L mice (Vβ11 genes, deleted) are weakly responsive to SEE. The results indicate that SEE activates mainly T cells bearing Vβ11 in physical association with MHC class II molecules expressed on AC. In addition, the results indicate that SEE activates both CD4 + T cells and CD8 + T Cells.