STAPHYLOCOCCAL-ENTEROTOXIN IS A BOVINE T-CELL SUPERANTIGEN

Different isoforms of soluble staphylococcal enterotoxins (SE): SEB, S EC-1 and SEC-2, were shown to stimulate bovine T cell proliferation, e xpression of cytokine messages, and IgG production. Intact metabolic f unction of APC was not required since peripheral blood mononuclear cel ls (PBMC), UV-irradiated prior to or following incubation with SE, wer e both capable of presenting SE, while PBMC treated with MAbs against MHC II lost the ability to stimulate T cell proliferation. SE caused a pproximately two fold increase of CD4+, and CD8+ T cells, but not MHC II+ APC or B cells. This model system suggests that SE transduces not only T cell activation signal, but also a non-proliferative signal for primary B cells to produce polyclonal IgG. We hypothesize that entero toxin virulence may be in part due to its effect on activating the imm une system.