Suppressor and reactive lymphocytes in radiation leukemia virus (RadLV)-induced leukemogenesis.
Suppressor cells capable of enhancing tumor growth in vivo and of abrogating a potential anti-tumor immunity in vitro are generated in C57BL/6 mice inoculated with the high-leukemogenic A-RadLV. Mice inoculated with low-leukemogenic D-RadLV do not develop suppressor cells but contain anti-tumor reactive lymphocytes that can inhibit in vivo tumor growth. Cyclophosphamide (CyF) treatment of mice inoculated with A-RadLV hampered suppressor cell function and rendered the animals' lymphocytes responsive to A-RadLV induced tumor cells in vitro. Administration of CyF also reduced leukemia incidence in mice inoculated with A-RadLV, but had no effect on leukemia induction by D-RadLV in irradiated mice. It is suggested that the high leukemogenic activity of A-RadLV depends on the virus' ability to recruit CyF-sensitive suppressor cells early in latency and that tumor progression in mice inoculated with D-RadLV is arrested due to the host immune response.
D000818:Animals; D003520:Cyclophosphamide / Q000494:pharmacology; D003602:Cytotoxicity, Immunologic; D005260:Female; D007108:Immune Tolerance; D007156:Immunologic Memory; D007942:Leukemia, Experimental / Q000276:immunology*; D008213:Lymphocyte Activation; D051379:Mice; D012190:Retroviridae; D013154:Spleen / Q000276:immunology; D050378:T-Lymphocytes, Regulatory / Q000276:immunology*
D003520:Cyclophosphamide