ANTIMETASTATIC ACTIVITY INDUCED BY CLOSTRIDIUM-BUTYRICUM AND CHARACTERIZATION OF EFFECTOR-CELLS

The effects of a bacterial vaccine, heat-killed Clostridium butyricum MII 588 cells, on the metastasis of B16-F10 melanoma in BDF1 mice was investigated. The vaccine stimulated natural killer (NK) cell cytotoxi c activity against YAC-1 target cells, which peaked at 72 hr after the pretreatment, whereas maximum macrophage cytotoxic activity was obtai ned on days 9 to 11. These stimulated cytotoxic activities were also o bserved in B16-F10 tumor-bearing BDF1 mice. The important role of stim ulated NK cells and/or macrophage in the antimetastatic effect was con firmed using Anti-asialo GM1 antibody, whole body x-ray irradiation an d carrageenan treatment. In addition, the vaccine could induce a high titer of interferon-gamma (IFN-gamma), an important lymphokine which m ay account for a significant portion of its antimetastatic activity.