Enhancement of LPS Triggered TNF-α (Tumor Necrosis Factor-α) Production by (1→3)-β-D-Glucans in Mice

Effects of (1→3)-β-D-glucans on tumor necrosis factor-α (TNF-α) production in mice in vivo were investigated with or without triggering stimulation of lipopolysaccharide (LPS). Administration of grifolan (GRN) (100-250 μg/mouse) obtained from Grifola frondosa, did not elevate the TNF-α concentration in serum, but significantly elevated LPS (10 μg/mouse)-elicited TNF-α production in serum. The priming effect was observed as early as 2 h after administration and remained high for 3 weeks. The priming effect was dependent on the strain of mice, i. e. ICR, BALB/c, and MRL/lpr (15 weeks old) showed high response. In addition, GRN administration increased membrane-bound TNF-α assessed by Western blotting and flow cytometry. Comparing the activity using structurally related glucans obtained from other microorganisms, highly branched glucans, SSG isolated from Sclerotinia sclerotiorum IFO 9395 and OL-2 from Omphalia lapidescence significantly increased TNF-α production. Small molecular weight GRN derivatives prepared by heat degradation method showed weaker priming effect. These facts suggested that the glucans showed priming effect of TNF-α production in vivo and that this effect was related to the degree of branching and molecular weight.