A TOXIC-SHOCK-SYNDROME-TOXIN-1 PEPTIDE THAT SHOWS HOMOLOGY TO AMINO-ACIDS-180-193 OF MYCOBACTERIAL HEAT-SHOCK PROTEIN-65 IS PRESENTED AS CONVENTIONAL ANTIGEN

Peripheral blood mononuclear cells (PBMC) from the majority of adults (12 out of 18 subjects tested) showed an in vitro proliferative respon se to a 20 amino acid long peptide (peptide 1, a.a 18-37) derived from TSST-1. In contrast, thymocytes and PBMC from cord blood did not prol iferate to this peptide. TSST-1 peptide 1 did not induce IL-1 beta mRN A in monocytes indicating that it does not behave as a superantigen. P roliferation of PBMC to peptide 1 could be blocked by anti-HLA-DR, but not by anti-HLA DP or DQ monoclonal antibodies suggesting that HLA-DR molecules are the restriction elements for the recognition of this pe ptide by T cells. Studies with subjects of known HLA-DR types showed t hat all types tested are capable of responding to this peptide. Peptid e 1 shows homology to a.a 180-193 of mycobacterial hsp 65 and was show n to stimulate the proliferation of T cell lines and T cell clone spec ific for the purified protein derivative (PPD) of Mycobacterium tuberc ulosis. This cross reactivity may confer on TSST-1 the potential to tr igger self reactivity and may also contribute to the natural immunity against TSST-1.