Effect of immunosuppression or immunostimulation on the growth rate of a lymphoid and of a myeloid leukemia in mice

Summary The influence of immunosuppression or immunostimulation on the growth rate of a lymphatic and of a myeloid murine leukemia has been investigated in syngeneic host-tumour relation. Immunosuppression by chemotherapy or X-rays, induced before transplantation of leukemia cells, did not change the survival time of the animals. Treatment with the immunosuppressive drug cortisone which is not cytostatic for these leukemias, if instituted after the transplantation of malignant cells, enhanced the growth rate of the lymphatic leukemia. Nonspecific stimulation with Corynebacterium parvum induced resistance to a graft of lymphatic leukemia in a majority of the mice, but only slowed the growth rate of myeloid leukemia, without preventing death. Immunosuppressive treatment, given before C. parvum, completely blocked the induction of resistance, and if given after C. parvum, abolished the established resistance to lymphatic leukemia. Thus, the danger of immunosuppression accompanying chemotherapy may lie in its abrogating the protective effects of nonspecific immunostimulation.Abbreviations PFC = plaque-forming-cell - SRBC = sheep red blood cell - cort. = cortisone - cyclo. = cyclophosphamide - L-asp. = L-asparaginase - mtx. = methotrexate - ara C = cytosine arabinoside - C.p. = Corynebacterium parvum