title: Specific lysis of Listeria monocytogenes-infected macrophages by class II-restricted L3T4+ T cells.
abstract: Mice were infected with the intracellular bacterium, Listeria monocytogenes, and T cell clones from spleens, lymph nodes and peritoneal exudates were established. The capacity of L3T4+, Lyt2- T-cell clones to specifically lyse L. monocytogenes-infected macrophages was analyzed. As a source of target cells, bone marrow macrophages (BMM phi) after 9 days of culture in hydrophobic teflon bags were used. These BMM phi were totally Ia-; however, significant Ia-expression could be induced by interferon-gamma (IFN-gamma). IFN-gamma-stimulated BMM phi, after priming with live or killed L. monocytogenes organisms were effectively lysed by the vast majority of L3T4+ T cell clones. In the absence of either IFN-gamma stimulation or antigen priming, no lysis occurred. Cytolysis was demonstrable in a conventional 4-h 51Cr-release assay and in an 18-h neutral red uptake assay and was antigen specific and class II restricted. Native T cells from L. monocytogenes-infected mice failed to lyse stimulated, L. monocytogenes-primed BMM phi and gained their cytolytic activity after antigenic restimulation in vitro. These data demonstrate that L. monocytogenes-specific L3T4+ T cells could lyse M phi presenting listerial antigens provided that Ia antigen expression had been induced. L3T4+ T cell clones produced IFN-phi after restimulation with antigen plus accessory cells in vitro and IFN-gamma secretion could be increased by costimulation with recombinant IL 2. These T cell clones conferred significant protection upon recipient mice which was more pronounced in the liver. The possible relevance of lysis by L3T4+ T cells of infected M phi to protection against and pathogenesis of intracellular bacterial infections is discussed.
mesh_terms: D000818:Animals; D000945:Antigens, Differentiation, T-Lymphocyte; D000954:Antigens, Surface / Q000032:analysis*; D003602:Cytotoxicity, Immunologic; D006681:HLA-D Antigens / Q000032:analysis; D008089:Listeria monocytogenes / Q000276:immunology*; D008088:Listeriosis / Q000276:immunology*; D008264:Macrophages / Q000276:immunology*; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D013045:Species Specificity; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D000945:Antigens, Differentiation, T-Lymphocyte; D000954:Antigens, Surface; D006681:HLA-D Antigens