title: Gamma interferon-dependent temporary resistance to acute Toxoplasma gondii infection independent of CD4+ or CD8+ lymphocytes.
abstract: It is well established that resistance to acute primary Toxoplasma gondii infection is mediated by a gamma interferon (IFN-gamma)-dependent mechanism. The present in vivo experiments were undertaken to investigate the cellular basis for this resistance. We show here that immunocompetent T. gondii-infected C57BL/6 (B6) mice treated with anti-IFN-gamma or with anti-Thy-1 or anti-asialo-GM1 antibodies die sooner than infected mice treated with antibodies that deplete both CD4+ and CD8+ T lymphocytes. Thy-1+ CD4- CD8- cells accumulated in the peritoneal cavities of B6 mice during the early stages of an intraperitoneal infection but did not accumulate in sham-infected control mice, and substantial numbers of Thy-1+ CD4- CD8- cells were recovered from the peritoneal cavities of infected B6 mice treated with antibodies that depleted CD4+ and CD8+ lymphocytes. Depletion of Thy-1+ cells reduced IFN-gamma to undetectable levels, whereas depletion of CD4+ and CD8+ cells did not reduce IFN-gamma levels. Thus T. gondii infection in immunocompetent B6 mice elicits Thy-1+ CD4- CD8- cells which either produce protective IFN-gamma themselves or control its production by other cells. It is likely that the function of these Thy-1+ CD4- CD8- cells is to control T. gondii tachyzoites during the early stages of primary infection before specific CD4(+)- and/or CD8(+)-dependent immunity develops.
authors.affiliation: Trudeau Institute, Inc., Saranac Lake, New York 12983.
authors.forename: L L
authors.initials: LL
authors.lastname: Johnson
authors.forename: F P
authors.initials: FP
authors.lastname: VanderVegt
authors.forename: E A
authors.initials: EA
authors.lastname: Havell
mesh_terms: D000818:Animals; D000954:Antigens, Surface; D000961:Antilymphocyte Serum / Q000494:pharmacology; D015704:CD4 Antigens; D016827:CD8 Antigens; D005260:Female; D007371:Interferon-gamma / Q000378:metabolism*; D007694:Killer Cells, Natural / Q000276:immunology; D008212:Lymphocyte Depletion; D008297:Male; D008562:Membrane Glycoproteins; D051379:Mice; D008810:Mice, Inbred C57BL; D016176:T-Lymphocyte Subsets / Q000276:immunology*; D018800:Thy-1 Antigens; D013997:Time Factors; D014124:Toxoplasmosis, Animal / Q000276:immunology*
chemical_list: D000954:Antigens, Surface; D000961:Antilymphocyte Serum; D015704:CD4 Antigens; D016827:CD8 Antigens; D008562:Membrane Glycoproteins; D018800:Thy-1 Antigens; D007371:Interferon-gamma