CD8+ T-cell interactions with Toxoplasma gondii: implications for processing of antigen for class-I-restricted recognition.

CD8+ T lymphocytes contribute to the control of acute and chronic T. gondii infection, and the activity of these cells is closely related to IFN gamma production. However, it is not clear whether CD8+ lymphocytes mediate protection solely by production of IFN gamma, or whether the lymphokine synergizes with CD8+ CTL activity. Interestingly, sensitization of bone marrow macrophages for CTL lysis can occur either as a result of infection or incubation with soluble T. gondii antigen. Thus, this system offers a powerful approach for analysing antigen processing pathways employed by intracellular protozoa, as well as for identifying the peptide epitopes which serve as targets for CD8(+)-dependent immunity.