In vitro generation of cytotoxic lymphocytes against radiation- and radiation leukemia virus-induced tumors. III. Suppression of anti-tumor immunity in vitro by lymphocytes of mice undergoing radiation leukemia virus-induced leukemogenesis.
Adult C57BL/6 mice exposed to fractionated irradiation or inoculated with the radiation leukemia virus (RadLV), develop high incidence (80-100%) of lymphatic leukemias within 3-6 mo. RadLV-induced lymphomas can elicit cytotoxic responses in vitro in lymphocytes of preimmunized syngeneic mice, a reaction that is dependent on the expression of membrane-associated viral antigenicity. As soon as 5 d after RadLV inoculation, and during the entire leukemogenic process, suppressor T cells are detectable in the spleen that are capable of specifically abrogating generation of syngeneic anti-tumor cytotoxic cells in vitro. Mice exposed to fractionated x irradiation do not develop suppressor cells and their splenocytes may be stimulated in vitro to generate cytotoxicity toward RadLV-induced leukemias. These findings suggest that although RadLV has been isolated from radiation-induced leukemias, x-ray- and RadLV-induced leukemogenesis do not seem to involve a common viral etiology, and that induction of suppressor cells during RadLV leukemogenesis may be essential for tumor progression.
D000818:Animals; D003602:Cytotoxicity, Immunologic; D004307:Dose-Response Relationship, Radiation; D005260:Female; D007108:Immune Tolerance; D009052:Leukemia Virus, Murine / Q000276:immunology; D007942:Leukemia, Experimental / Q000276:immunology*; D007953:Leukemia, Radiation-Induced / Q000276:immunology*; D008223:Lymphoma / Q000276:immunology; D051379:Mice; D013601:T-Lymphocytes / Q000276:immunology*; D050378:T-Lymphocytes, Regulatory / Q000276:immunology