Induction of immunomodulating cytokines by polysaccharides from Dendrobium huoshanense

The immunomodulating activities of polysaccharides from Dendrobium huoshanense C. Z. Tang et S. J. Cheng (Orchidaceae) (HPS) were assessed. Crude HPS at concentrations of 100 to 200 mu g/mL significantly stimulated tumor necrosis factor-alpha (TNF-alpha) release in the supernatant of peritoneal macrophages, and interferon-gamma (IFN-gamma) release in the supernatant of murine splenocytes was also enhanced by 100 to 800 mu g/mL of crude HPS. The maximum values of 542.9 pg/mL (TNF-alpha) and 790.1 pg/mL (IFN-gamma) were obtained at the 24th hour of culture. RT-PCR analysis indicated that enhancement of both TNF-alpha and IFN-gamma release by HPS was attributed to the upregulation of the expression of the corresponding genes in cells. Different HPS fractions showed different activities. Among all fractions from anion-exchange chromatography and gel filtration, three fractions of HPS1A, HPS1B, and HPS2B had more potent effect on IFN-gamma and TNF-alpha release than the crude HPS. These results suggest that HPS might induce an immune response.