Immunological studies on sporamycin-treated animals.

Sporamycin showed a remarkable tumor regressive activity against sarcoma-180 with a single 5 mg/kg dose of intravenous administration. This antitumor effect on tumor and host animals was examined immunologically. As the results: (1) When sarcoma-180 tumor cells were used as an antigen macrophage migration inhibition reaction by spleen cells derived from the tumor-bearing mice treated with sporamycin was positive at day 7 approximately 14 after the medication and was negative thereafter. (2) The delayed hypersensitivity tested by the foot-pad reaction was positive in tumor-bearing mice treated with sporamycin, and no decrease of foot pad reaction was observed, whereas this reaction decreased remarkably in non-treated tumor-bearing mice. (3) Sarcoma-180 tumor cells were mixed with spleen cells derived from sporamycin-treated mice, and were inoculated into normal dd mice. The growth of tumor cells was inhibited markedly, but no inhibition of tumor growth was observed in case of spleen cells derived from non-treated tumor bearing mice. (4) Combined treatment of sporamycin with PS-K, an immunopotentiator, showed a remarkable synergistic effect.