Toxic Shock Syndrome Toxin-1 (TSST-1) (58-78)

Toxic shock syndrome toxin-1 (TSST-1) is a "superantigen" which binds to MHC class II molecules and induces a polyclonal stimulation of T cells. In this communication by using a FACS technique and a 21-mer synthetic peptide from the primary sequence of TSST-1 (KGEKVDLNTKRTKKSQHTSEG), designated TSST-1(58-78), we demonstrated binding of the peptide only to cells bearing MHC class II. The proliferative effect of TSST-1(58-78) on human T cells was shown to be inhibited much more by anti-HLA-DR than by anti-HLA class I antibody. Furthermore, human monocytes were able to present TSST-1(58-78) to a mouse VSV specific T cell clone by a xenostimulatory mechanism. These data indicate this peptide to contain an active site of the TSST-1 holotoxin.

A 21-mer synthetic peptide (KGEKVDLNTKRTKKSQHTSEG), designated TSST-1(58-78), was constructed from the primary structure of the toxic shock syndrome toxin 1 (TSST-1). The peptide reacted with a panel of neutralizing monoclonal antibodies (MAbs) to whole TSST-1 in solid-phase immunoassays. TSST-1(58-78) promoted the in vitro proliferation of human peripheral blood mononuclear cells (PBMC) in a dose-dependent manner. Minimum dose required for stimulation (P less than or equal to .05 microM) was 0.75 microM peptide. This mitogenic effect was abrogated by incubation of the peptide with MAbs to whole TSST-1 before addition to PBMC. The ability of TSST-1(58-78) to stimulate the proliferation of highly purified resting human T cells was analyzed. Significant proliferation (P less than or equal to .01) was observed only in the presence of increasing populations of monocytes added to the cultures. Adherent human monocytes exposed to TSST-1(58-78) released tumor necrosis factor. Thus, some of the immunoregulatory properties attributed to TSST-1 are demonstrated by the region of the toxin represented by the peptide TSST-1(58-78).

Toxic shock syndrome toxin-1 (TSST-1) is a "superantigen" which binds to MHC class II molecules and induces a polyclonal stimulation of T cells. In this communication by using a FACS technique and a 21-mer synthetic peptide from the primary sequence of TSST-1 (KGEKVDLNTKRTKKSQHTSEG), designated TSST-1(58-78), we demonstrated binding of the peptide only to cells bearing MHC class II. The proliferative effect of TSST-1(58-78) on human T cells was shown to be inhibited much more by anti-HLA-DR than by anti-HLA class I antibody. Furthermore, human monocytes were able to present TSST-1(58-78) to a mouse VSV specific T cell clone by a xenostimulatory mechanism. These data indicate this peptide to contain an active site of the TSST-1 holotoxin.