Relative activities of distinct isotypes of murine and human major histocompatibility complex class II molecules in binding toxic shock syndrome toxin 1 and determination of CD antigens expressed on T cells generated upon stimulation by the toxin.

Relative abilities of murine and human major histocompatibility complex class II molecules to bind toxic shock syndrome toxin 1 (TSST-1) and T-cell subsets activated by the toxin were investigated. TSST-1 binding was observed in L cells transfected with I-Ab, I-Ak, DR2, and DQw1 genes. Scatchard plot analysis showed similar Kd values (1 x 10(-8) to 3 x 10(-8) M) for these cells. By comparison, binding was not detected in L cells transfected with I-Ek, DPw4, and DP(Cp63) genes. All of the transfectants supported TSST-1-induced proliferative response and interleukin-2 production by murine and human T cells. Levels of accessory activity were lower in the I-Ek transfectants and the DPw4 and DP(Cp63) transfectants than in the I-Ab and I-Ak transfectants and the DR2 and DQw1 transfectants, respectively. The results indicate that I-A, DR, and DQ molecules bind TSST-1 with similar affinities, whereas I-E and DP molecules bind it with fairly low affinity. TSST-1-activated T cells consisted of both CD4+ and CD8+ T cells, indicating that TSST-1 activates these two T-cell subsets.