title: The killing of tumour cell targets coupled to tuberculin (PPD) by human and murine PPD-reactive T helper clones. I. PPD specificity of killing.
abstract: This paper reports on the characteristics of killing by a human and a murine tuberculin (PPD)-specific T helper clone of targets to which PPD was attached via the lectin concanavalin A (Con A). The killing was specific for PPD from M. tuberculosis; and targets coupled to Con A alone or to PPD from M. paratuberculosis were not killed. Target cells carrying Con A-PPD were more effectively lysed than PPD-pulsed cells. This form of lymphocyte killing, though highly significant, was inefficient. Maximum killing of PPD carrying targets was 30-40% at effector to target ratios of 20:1 and at 16 h. Cells carrying 2 x 10(6) molecules of PPD and less than 1.5 x 10(6) molecules Con A per cell were killed most efficiently. A major distinction between this helper T cell killing and that mediated by cytotoxic T cells was that both TH clones displayed bystander lysis and killed PPD uncoupled targets when these were cultured with syngeneic PPD-bound targets. This suggests that the mechanism of cytotoxicity may involve soluble mediators.
mesh_terms: D000818:Animals; D002461:Cell Line, Transformed; D002999:Clone Cells / Q000276:immunology; D003208:Concanavalin A / Q000032:analysis / Q000276:immunology; D003602:Cytotoxicity, Immunologic; D004306:Dose-Response Relationship, Immunologic; D000939:Epitopes / Q000276:immunology*; D005354:Fibrosarcoma / Q000276:immunology; D004854:Herpesvirus 4, Human; D006801:Humans; D004915:Leukemia, Erythroblastic, Acute / Q000276:immunology; D051379:Mice; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology*; D013997:Time Factors; D014373:Tuberculin / Q000032:analysis / Q000276:immunology*; D014407:Tumor Cells, Cultured
chemical_list: D000939:Epitopes; D014373:Tuberculin; D003208:Concanavalin A