Abstract
DMG (degraded mannoglucan ; MW: about 3×105) prepared from a mannoglucan (MW: about 9×105) produced byMicroellobosporia grisea, showed a marked inhibitory effect on the growth of subcutaneously transplanted sarcoma 180. Pretreatment of mice with a single injection of 100 mg/kg of DMG 6 days before the transplantation could also induce a remarkable effect. On the other hand, DMG failed to inhibit the growth of ascites tumor of sarcoma 180. DMG proved to induce prolongation of life-span of mice infected withMycobacterium tuberculosis.The time course for the change of viable number ofM. tuberculosisin lungs revealed that the multiplication of infected bacteria was markedly suppressed, as compared to that of control mice. The lesions of lungs of DMG-treated mice exhibited tendency toward histopathological characteristics of proliferative-granulomatous type, while necrotic-exudative changes were predominant in control groups. Marked enhancement of delayed-type hypersensitivity to PPD was recognized in DMG-treated group. Among bacteria other thanM. tuberculosis, the pretreatment with DMG showed protective effect on experimental infections ofStaphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Proteus vulgaris and Serratia marcescens. The pretreatment of mice with DMG proved to increase the number of hemolytic plaque-forming cells of spleen after immunization with sheep red blood cells. Significant enhancement of delayed cutaneous hypersensitivity to picryl chloride could also be observed in mice treated with DMG.
