title: Immunosuppression by spleen cells from Moloney leukemia. III. Evidence for a suppressor cell that is not the leukemic, virus-producing cell.
abstract: Spleens of mice bearing MuLV (Moloney)-induced leukemia contain cells that inhibit the antibody response of normal syngeneic lymphocytes to sheep RBC in Marbrook cultures. In order to determine whether these immunosuppressive cells are virus-infected tumor cells or normal cells we pretreated leukemic spleen cell suspensions with syngeneic mouse antiserum to Moloney leukemia antigen(s) (plus complement) and with rat anti-Moloney serum (plus complement). The cytotoxic treatment killed approximately 20% to 30% and 60% to 70% of the cells, respectively. The remaining viable cell population was tested for MuLV production (in an infectious center assay on S+L-fibroblasts), for lethal effect on newborn mice, and for immunosuppressive activity. After the treatment with anti-Moloney sera the number of MuLV-releasing cells decreased 10-fold and the leukemogenic potential in vivo decreased 100-fold as compared to leukemic spleen cells pretreated with nonimmune mouse and rat sera (plus complement). In contrast, the ability of the antisera-treated cells to inhibit anti-SRBC response remained undiminished. This indicates that, in part, the immunosuppressive cells in the leukemic spleen are normal, noninfected cells, involved, perhaps, in immune regulation.
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002471:Cell Transformation, Neoplastic; D003601:Cytotoxicity Tests, Immunologic; D005260:Female; D006462:Hemolytic Plaque Technique; D007106:Immune Sera / Q000494:pharmacology; D007165:Immunosuppression Therapy; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008979:Moloney murine leukemia virus / Q000276:immunology*; D013154:Spleen / Q000276:immunology*; D014412:Tumor Virus Infections / Q000209:etiology* / Q000401:mortality
chemical_list: D007106:Immune Sera