Abstract
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.