Immunopotentiating activity of Clostridium butyricum in mice.

Bacterial vaccine, as generated by heat-inactivated Clostridium butyricum cells, displayed antitumor activity against sarcoma 180 in DDY mice and antimetastatic activity against B16-F10 melanoma in BDF1 mice. According to our results, the vaccine has no direct growth inhibitory effect toward the tumor cell lines tested in this study. The vaccine increased gamma-interferon production, elicited delayed type hypersensitivity reaction, and enhanced IgM antibody formation and mitogenicity. The phagocytic activity of macrophage and killing activity of NK cells from mice were enhanced in a dose-dependent manner by stimulating with the heat-inactivated vaccine. Among those responses in the mice treated with CB, elevated NK cell activity may play a prominent role in manifesting antitumor activity in the B16-F10 metastasis experiment.