title: Protein-antigen specific Ia-restricted cytolytic T cells: analysis of frequency, target cell susceptibility, and mechanism of cytolysis.
abstract: We previously showed that cloned, antigen-specific, Ia-restricted L3T4a+ T cell lines can be cytolytic for antigen-pulsed B cell lymphoma targets. Such cells can also, under different experimental conditions, activate B cells to proliferate and secrete immunoglobulin. In the present experiments, we show that this functional phenotype is a common one among a panel of cloned T cell lines. In keeping with this finding, freshly isolated, antigen-activated lymph node T cells show similar functional properties. Such cytolytic L3T4a+ T cells differ from classical H-2K/D-restricted cytolytic T cells in two distinct ways. First, Ia-restricted cytolytic T cells can kill bystander targets, whereas H-2K/D-specific cytolytic T cells do not. Second, in testing a panel of target cells by using lectin-mediated cytolysis, Ia-restricted cytolytic clones reveal large differences in target cell susceptibility, whereas all targets are similarly susceptible to H-2K/D-specific killer cells. Finally, evidence is presented that both direct and bystander killing effected by L3T4a+ T cells are mediated by the same soluble factors, in that there is a strong positive correlation of these two activities for individual cloned lines. The relevant mediators appear to be lymphotoxin and IFN-gamma, although the latter molecule by itself is not cytolytic on our target lines.
authors.forename: J P
authors.initials: JP
authors.lastname: Tite
authors.forename: M B
authors.initials: MB
authors.lastname: Powell
authors.forename: N H
authors.initials: NH
authors.lastname: Ruddle
mesh_terms: D000818:Animals; D000954:Antigens, Surface; D002460:Cell Line; D002999:Clone Cells / Q000276:immunology; D003601:Cytotoxicity Tests, Immunologic / Q000379:methods; D003602:Cytotoxicity, Immunologic; D000939:Epitopes; D000949:Histocompatibility Antigens Class II / Q000276:immunology*; D007700:Kinetics; D016169:Lymphocyte Function-Associated Antigen-1; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D010047:Ovalbumin / Q000276:immunology*; D010641:Phenotype; D013602:T-Lymphocytes, Cytotoxic / Q000145:classification* / Q000276:immunology; D013997:Time Factors
chemical_list: D000954:Antigens, Surface; D000939:Epitopes; D000949:Histocompatibility Antigens Class II; D016169:Lymphocyte Function-Associated Antigen-1; D010047:Ovalbumin