ACTIVATION OF INVITRO PROLIFERATION OF HUMAN T-CELLS BY A SYNTHETIC PEPTIDE OF TOXIC SHOCK SYNDROME TOXIN-1

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) was 0.75-mu-M 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).