In vivo transfer of antitumor activity by peritoneal exudate cells from mice treated with Corynebacterium parvum: Reduced effect in irradiated recipients

Experiments were undertaken to study in vivo the antitumor activity of transferred peritoneal exudate cells (PEC) from Corynebacterium parvum-treated C3Hf/Bu mice. Inhibition of tumor growth was demonstrated when fibrosarcoma cells admixed with C. parvum-stimulated PEC (CP-PEC) were transplanted either ip or sc; the level of effect increased with the ratio of effector to target cells. In ip transfer experiments, the activity of transferred CP-PEC was substantially reduced when recipient mice were pretreated with 600 rads whole-body irradiation. Reconstitution of whole-body-irradiated (WBI) mice with mixed normal spleen and lymph node cells, spleen cells alone, or normal bone marrow cells did not restore the antitumor activity of transferred CP-PEC. Indeed, mice reconstituted ip showed a poorer transferred antitumor response than unreconstituted WBI mice. Inhibition of CP-PEC activity was also observed in sc transfer experiments when normal PEC, spleen cells, or separated T-cells were admixed with tumor cells and CP-PEC. However, admixed fetal fibroblasts, radiation-killed tumor cells, washed erythrocytes, or inert plastic microspheres also inhibited the action of CP-PEC to an equal or greater extent, which indicated that the inhibitory effect did not depend specifically on the presence of lymphoid elements. Possible reasons for the markedly reduced antitumor activity of CP-PEC transferred into WBI recipients were considered in the light of the experimental results.