SUBSETS OF HLA-DR1 MOLECULES DEFINED BY SEB AND TSST-1 BINDING

Superantigens bind to major histocompatibility complex class II molecu les on antigen-presenting cells and stimulate T cells. Staphylococcus aureus enterotoxin B (SEB) and toxic shock syndrome toxin-1 (TSST-1) b ind to the same region of human lymphocyte antigen (HL4)-DR1 but do no t compete with each other, which indicates that they bind to different subsets of DR1 molecules. Here, a mutation in the peptide-binding gro ove disrupted the SEB and TSST-1 binding sites, which suggests that pe ptides can influence the interaction with bacterial toxins. in support of this, the expression of the DR1 molecule in various cell types dif ferentially affected the binding of these toxins.