[Effects of SSM, an extract from human type tubercle bacilli, on syngenic guinea pig tumors]

SSM (specific substance of Maruyama) is used widely in cancer therapy. Rats and mice have generally been used in basic research. In this study the author used guinea pigs because their skin properties are easier to monitor than those of rats and mice. The following experiments were performed on guinea pigs: 1) Potency as sensitizer and elicitor of delayed hypersensitivity. 2) Antitumor effects on methylcholanthrene induced syngenic guinea pig tumors (U-1). Intradermal skin tests with 20 micrograms of SSM per 0.1 ml were done on guinea pigs 4 weeks after sensitization (SSM 1 mg-FIA (Freund's incomplete adjuvant]. SSM induced a delayed skin reactivity and the reaction increased in erythema and in duration after 24 h. In addition, SSM was active in direct inhibition of macrophage migration. The results show that SSM is related to cellular immunity reactions. In this study, antitumor effects of SSM were indicated in that the tumor growth was more greatly suppressed in animals injected intravenously and subcutaneously than in control animals. Histologic study of the tumors showed that collagen fibers enclosed the cancer cells and prevented cancer proliferation.