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.