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

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Abstract
Peripheral blood mononuclear cells (PBMC) from the majority of adults (12 out of 18 subjects tested) showed an in vitro proliferative response 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 proliferate to this peptide. TSST-1 peptide 1 did not induce IL-1β mRNA in monocytes indicating that it does not behave as a superantigen. Proliferation 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 peptide by T cells. Studies with subjects of known HLA-DR types showed that all types tested are capable of responding to this peptide. Peptide 1 shows homology to a.a 180–193 of mycobacterial hsp 65 and was shown to stimulate the proliferation of T cell lines and T cell clone specific for the purified protein derivative (PPD) of Mycobacterium tuberculosis. This cross reactivity may confer on TSST-1 the potential to trigger self reactivity and may also contribute to the natural immunity against TSST-1.