STIMULATION OF HUMAN T-LYMPHOCYTES OBTAINED FROM TOXOPLASMA-GONDII - SERONEGATIVE PERSONS BY PROTEINS DERIVED FROM TOXOPLASMA-GONDII

Toxoplasma gondii antigens are superantigens in mice. To investigate a superantigen effect in humans, lymphocytes from T. gondii-seronegativ e subjects were studied for proliferation to T. gondii antigens (TA). Marked cellular proliferation, predominantly of CD4(+) lymphocytes, wa s apparent. TA elicited expansions of V beta-bearing lymphocytes in al l subjects, but different V beta-bearing lymphocytes were expanded in different subjects in both CD4(+) and CD8(+) subpopulations. Cord bloo d cells also proliferated to TA. Previously fixed antigen-presenting c ells were unable to present TA. Thus, T. gondii appears to produce a m olecule(s) that induces polyclonal activation of human T cells and req uires antigen processing to mediate this effect. That T. gondii does n ot appear to behave as a superantigen in humans is important in unders tanding the pathogenesis of T. gondii infection in immunocompromised h osts and in the design of anti-T. gondii vaccines.