Effects of maitake (Grifola frondosa) polysaccharide on collagen-induced arthritis in mice

We recently reported the anti-hepatitis effect of a polysaccharide, designa ted as the D-fraction, extracted from maitake. Its effect includes immune-r egulating activities. We investigated the effect of the glucan in collagen- induced arthritis (CIA). The D-fraction was administered to CIA mice for 30 consecutive days. Arthritis development was observed from the 4th day afte r the second immunization. The D-fraction did not have any influence on ant i-type II collagen antibodies in blood serum or activated B cells. To deter mine how cellular immunity may be involved in the development of CIA, ratio s of CD4(+) T cells and their activated form in the axillary and inguinal l ymph node T cells were detected by flow cytometry analysis. The ratios were not different between the D-fraction group and the control group. However, interleukin-1 beta, granulocyte-macrophage colony-stimulating factor and t umor necrosis factor-alpha productions from splenic macrophages were signif icantly increased to 2.0, 4.7 and 1.9 times the control group level, respec tively. The ratio of macrophages in the whole spleen cells was 2.3 times th at of the control group, and their migrating ability was 1.9 times higher. Based on these results, we concluded that the arthritis development induced by D-fraction administration is attributable to the activation of splenic macrophages.