[A mechanism involved in augmentation of anti-tumor immunity by irradiation to the tumor: tumor irradiation promoted generation of CD4+helper T cells against a murine immunogenic tumor].
It has long been suggested but not generally accepted that anti-tumor immunity is enhanced by irradiation of the tumor. In this study, the mechanism involved in enhancing the effect of irradiation on tumor immunity was analyzed. 20 Gy of irradiation to a murine hepatoma, MH134, in the thigh muscle of syngeneic C3H/He mice, augmented the generation of cytotoxic T cells (CTL) in the spleen. It was assumed that radiation-damaged apoptotic tumor cells are readily phagocytosed by macrophages and that tumor specific transplantation antigen (TSTA) is presented as a complex with MHC class II antigen on macrophages to CD4+ T cells. To examine the hypothesis, that irradiated tumor cells induce CD4+ helper T cells required for the generation of CD8+ CTL, C3H/He mice were immunized with 2 x 10(7) MH134 cells which contained irradiated tumor cells (100 Gy, in vitro) at varying ratios. When irradiated tumor cells are contained at levels of 60-80%, the generation of helper T cells as well as CTL against the tumor was significantly enhanced. The findings obtained suggest that tumor irradiation enhances anti-tumor immunity by promoting the induction of antigen-specific helper T cells, which play a key role in anti-tumor immunity, i.e., either generating CTL or antibody-forming B cells depending on the activity of TH1 or TH2 subset cells.
Makidono
R
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Department of Immunology, Kurume University School of Medicine.
D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology*; D002454:Cell Differentiation / Q000528:radiation effects; D003602:Cytotoxicity, Immunologic / Q000528:radiation effects*; D005260:Female; D008114:Liver Neoplasms, Experimental / Q000276:immunology* / Q000532:radiotherapy*; D051379:Mice; D008809:Mice, Inbred C3H; D016499:Radioimmunotherapy; D006377:T-Lymphocytes, Helper-Inducer / Q000166:cytology / Q000276:immunology*