Induction of Immunomodulating Cytokines by Polysaccharides fromDendrobium 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 µg/mL significantly stimulated tumor necrosis factor-α. (TNF-α.) release in the supernatant of peritoneal macrophages, and interferon-γ. (IFN-γ.) release in the supernatant of murine splenocytes was also enhanced by 100 to 800 µg/mL of crude HPS. The maximum values of 542.9 pg/mL (TNF-α.) and 790.1 pg/mL (IFN-γ.) were obtained at the 24th hour of culture. RT-PCR analysis indicated that enhancement of both TNF-α. and IFN-γ. 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-γ. and TNF-α. release than the crude HPS. These results suggest that HPS might induce an immune response.