Potentiation of antitumor immunity in tumor-bearing mice by a degraded D-manno-D-glucan (DMG), a new antitumor polysaccharide.
DMG, a degraded D-manno-D-glucan from the culture fluid of Microellobosporia grisea, inhibited the growth of murine syngeneic MM46 mammary carcinoma. Mice in which the tumor had completely regressed by DMG treatment showed tumor-specific antitumor resistance. The antitumor action of DMG was studied by examining the influences of DMG on tumor-specific and non-specific immune responses in tumor-bearing hosts. The tumor-specific delayed hypersensitivity reaction appeared transiently on day 7 after tumor inoculation but had decreased by day 15 in untreated tumor-bearing mice. In contrast, the reaction was retained and augmented in DMG-treated tumor-bearing mice. The tumor-neutralizing activity of spleen cells from DMG-treated tumor-bearing mice, tested by a Winn assay, was tumor-specific and significantly higher than that of untreated tumor-bearing mice. The tumor-neutralizing activity of peritoneal cells and the in vitro cytostatic activity of peritoneal macrophages in response to lymphokine supernatants containing macrophage activation factor were also augmented by DMG treatment. In contrast, the level of antitumor antibody in the serum increased with time, irrespective of DMG administration. Thus, DMG potentiated cellular antitumor effector mechanisms.
D000818:Animals; D000917:Antibody Formation / Q000187:drug effects; D000970:Antineoplastic Agents / Q000276:immunology*; D006968:Hypersensitivity, Delayed; D007111:Immunity, Cellular / Q000187:drug effects; D008264:Macrophages / Q000187:drug effects; D008297:Male; D008325:Mammary Neoplasms, Experimental / Q000188:drug therapy / Q000276:immunology*; D051379:Mice; D008809:Mice, Inbred C3H; D013997:Time Factors
D000970:Antineoplastic Agents