Activities of polysaccharides obtained fromGrifola frondosa on insulin-dependent diabetes mellitus induced by streptozotocin in mice

In an experiment with C57BL/6J model mice having insulin-dependent diabetes mellitus (IDDM) induced by streptozotocin, the glucans obtained from Maitake fruit-body were found to suppress activation and proliferation of macrophages and consequently to inhibit the generation of nitric oxide (NO) and IL (interleukin)-1 β, which are β-cell destruction factors, suppressing their production to 0.17 and 0.33, respectively, relative to the control mice. In addition, the glucans caused proliferation and activation of B cells, as detected by flow cytometric analysis of whole spleen cell lymphocytes. Cytokine secretion from whole spleen cells was also investigated by ELISA, which showed that IFN-γ production was suppressed while IL-4 production increased. These glucans, acting in the diabetic mice, accelerate recovery of Th2 cell functions, regulate the balance between Th1 cells and Th2 cells, and consequently repress the cytotoxic reaction. In spite of the effect of the glucans on the immune reactions, IDDM itself does not show any favorable signs of recovery. For the result, some other factors are suggested to be acting in the complex immunity network in relation to IDDM generation.