Immunostimulatory activity of the polysaccharides from Hyriopsis cumingii

The immunostimulatory activity of Hyriopsis cumingii polysaccharides (HCPS) was evaluated by using in vitro cell models and in vivo animal models. The results demonstrated that crude HCPS and its purified fractions (HCPS-1, HCPS-2 and HCPS-3) could promote the splenocyte proliferation, increase the activity of acid phosphatase in peritoneal macrophages and strengthen peritoneal macrophages to devour neutral red in vitro in a dose-dependent manner. Furthermore, HCPS-3 exhibited much stronger immunostimulatory activity in vitro than crude HCPS, HCPS-1 and HCPS-2, probably due to the higher sulfate content of HCPS-3. For assay in vivo, crude HCPS significantly increased the indices of spleen and thymus, the activity of lysozyme in serum and the swelling rate of earlap in delayed-type hypersensitivity in a dose-dependent manner. These results suggested that HCPS might be a potential natural immunomodulator.