Local induction of a tumor necrosis factor (TNF)-like cytotoxic factor in murine tissues with tumorous and nontumorous inflammation after systemic administration of antitumor polysaccharides.

Abstract

Local induction of a cytotoxic factor (CF), which was reported by us to be a tumor necrosis factor (TNF)-like molecule, in murine tumor tissues by i.v. administration of antitumor polysaccharides was studied. The CF was measured by cytolysis assay against L929 fibroblasts in vitro. The antitumor polysaccharides mannoglucan polyalcohol (MGA), lentinan, carboxymethyl-(1----3)-beta-D-linear glucan DP540 (CM-TAK) and yeast mannan induced the CF in MH134 hepatoma tissues inoculated intradermally, with MGA inducing the highest level of the CF. MGA induced the CF in MM46 mammary carcinoma, Ehrlich carcinoma, and MH134 hepatoma, the growth of which were all inhibited by MGA, but not in Lewis lung carcinoma and EL-4 lymphoma, which are therapeutically resistant to MGA. MGA induced the CF in solid MH134 hepatoma tissues inoculated subcutaneously or intramuscularly as well as intradermally, but not in ascitic fluids with intraperitoneal MH134 hepatoma on which MGA is ineffective. These findings suggest that CF induction is correlated with the antitumor activity of polysaccharides. CF induction in tumor tissues was detectable 6 h after i.d. inoculation of MH134 hepatoma. Even in nontumorous inflammatory skin tissues produced by injection of TAK, the CF was induced by MGA. Thus, the early inflammatory reaction with accumulation of host cells and MGA treatment act cooperatively in local induction of the CF.