TISSUE DISTRIBUTION OF INTRAPERITONEALLY ADMINISTERED (1-]3)-BETA-D-GLUCAN (SSG), A HIGHLY BRANCHED ANTITUMOR GLUCAN, IN MICE

Distribution of metabolically H-3-labeled (1 --> 3)-beta-D-glucan (H-3-SSG) obtained from the culture filtrate of Sclerotinia sclerotiorum IFO 9395, in various tissues after intraperitoneal administration into ICR mice (250 mug/mouse) was examined. H-3-SSG was mainly detected in liver, spleen, and blood, and a negligible amount was excreted into the feces and excrement within 2 d. The significant amount of H-3-SSG remained in liver and spleen after 1 month. On the other hand, SSG was not incorporated effectively in vivo and in vitro by peritoneal exudate macrophages (0.5 mug/1 x 10(6) Mphi). Similarly in vivo, the majority of H-3-SSG distributed in spleen and liver were recovered from the non-cellular fraction and not from splenic macrophage and Kupffer cell fractions. These results suggested that (1 --> 3)-beta-D-glucans would not be easily incorporated by the host cells to degrade and exclude from the body even after the onset of the biological response modifier activity.