IMMUNOLOGICALLY MEDIATED EFFECT OF LONG-L IVING RADIONUCLIDES FROM A BREAKDOWN EJECTION OF THE CH APS ON EXPERIMENTAL TUMOR PROCESS

A complex immunological investigation was carried out and peculiaritie s of growth and metastasizing of neoplasias induced by the inoculation of transplantable tumor cells (LL) were examined in the C57BI mice ha ving been constantly kept (since antenatal period) under conditions of exposure to external and internal irradiation of natural spectrum rad ionuclides having fallen as a result of the Ch.A.P.S. accident. Distur bances in immune status of the irradiated mice were demonstrated to af fect the major chains of antitumor resistance: different subpopulation s of T-lymphocytes, natural killer cells, and mononuclear phagocyte sy stem cells. A decline in antitumor resistance of the irradiated mice a s compared to intact animals manifests itself in a rise of rate of tum ors induced by LL cells (a ratio of relative risks was 1.23), in signi ficant reduction of the latent period duration, and in significant dec rease in antitumor efficiency of lymphocytes isolated during latent pe riod in respect to homological tumor cells. Tumor growth and metastasi zing in the irradiated mice proceeds slower than in controls. One mech anism of this phenomenon is a delay in the development of tumor-associ ated kinds of suppression.