IMMUNOSUPPRESSION BY SPLEEN-CELLS FROM MOLONEY LEUKEMIA .3. EVIDENCE FOR A SUPPRESSOR CELL THAT IS NOT LEUKEMIC, VIRUS-PRODUCING CELL

  • 1 January 1977
    • journal article
    • research article
    • Vol. 119  (3) , 1097-1101
Abstract
Spleens of mice bearing MuLV (Moloney leukemia virus)-induced leukemia contain cells that inhibit the antibody response of normal syngeneic lymphocytes to sheep RBC [erythrocytes] in Marbrook cultures. To determine whether these immunosuppressive cells are virus-infected tumor cells or normal cells leukemic spleen cell suspensions were pretreated with syngeneic mouse antiserum to Moloney leukemia antigen(s) (plus complement) and with rat anti-Moloney serum (plus complement). The cytotoxic treatment killed approximately 20-30% and 60-70% of the cells, respectively. The remaining viable cell population was tested for MuLV production (in an infectious center assay on S+L- [sarcoma positive, leukemia negative] 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). The ability of the antisera-treated cells to inhibit anti-RBC response remained undiminished. This indicates that, in part, the immunosuppressive cells in the leukemic spleen are normal, noninfected cells involved, perhaps, in immune regulation.