T lymphocyte-dependent effector mechanisms of immunity to Toxoplasma gondii

Immunity to the opportunistic pathogen, Toxoplasma gondii, is highly depend ent upon the effector activity of IFN-gamma-producing T lymphocytes. While IFN-gamma is required to survive infection, an understanding of its functio n remains incomplete. During infection, T. gondii simultaneously induces do wnregulatory antiinflammatory cytokines, thereby avoiding major host pathol ogy mediated by proinflammatory cytokines such as IFN-gamma. The ability to induce the correct balance between these two opposing host responses likel y accounts for the success of this organism as a parasite. (C) Elsevier, Pa ris.