Abstract
Lactobacillus casei YIT 9018 (LC-9018), a new microorganism preparation with immunomodulatory properties, has been found to have an anti-tumor effect: the mechanism of immunological anti-tumor effect of LC-9018 in Meth A (methylchoranthren-induced tumor cell) transplanted BALB/c mice was investigated. In normal BALB/c mice, interferon (IFN) was found in the serum of mice after intra-peritoneal injection of LC-9018, and the maximum concentration of IFN in the serum appeared 32 hrs later. Macrophage activating factor (MAF) was also detected in LC-9018 administered mice. The maximum activity of MAF was found 72 hrs after LC-9018 administration. After the administration of LC-9018, the cytotoxic activity of splenial macrophage (MAC) was maintained at about fivehold as high level of activity as that in the placebo administered mice. In the administration of LC-9018 in Meth A transplanted BALB/c mice, the tumor growth of mice was suppressed to about 60% on the 22nd day after the Meth A transplantation. The cytotoxicity of splenial MAC was maintained at higher levels in Meth-A bearing mice which received LC-9018. Augmentation of MAC cytotoxicity and the anti-tumor effect in LC-9018 administered mice were similar to those with the administration of recombinant murine IFN-γ (rMuIFN-γ). The result suggests that IFNs and MAF induction by LC-9018 plays an important role in achieving an anti-tumor effect on malignant tumors.
