Abstract:To evaluate the immunoregulatory effect of polysaccharide from Hippophae rhamnoides L. （PHR） on immune dysfunction in cyclophosphamide （CTX）-induced immunosuppressed mice，PHR isolated and prepared from H. rhamnoides L. was used as the test sample. Mice were divided into blank group，CTX model group，and low-，medium-，and high-dose PHR groups （100，200，and 400 mg/kg）. The immunosuppressed mouse model was established using CTX，followed by PHR administration via gavage. The immune organ index，phagocytosis index，serum levels of immunoglobulin G（IgG），immunoglobulin M （IgM），tumor necrosis factor-alpha （TNF-α），interferon-gamma （IFN-γ），interleukin-6 （IL-6），and the proliferation ability of spleen lymphocytes in each group were measured using weighing，carbon clearance，enzyme-linked immunosorbent assay （ELISA），and 3-（4，5-dimethylthiazol-2-yl）-2，5-diphenyltetrazolium bromide （MTT） assay. The results showed that compared with the blank group，the model group exhibited significantly reduced immune organ index，phagocytosis index，serum levels of IgG，IgM，TNF-α，IFN-γ，IL-6，and lymphocyte proliferation capacity（P＜0.01）. Compared with the model group，each dose group of PHR showed improvement in the above indexes，with the medium-and high-dose groups demonstrating significantly greater effects （P＜0.05）. Therefore，PHR can alleviate immune dysfunction in CTX-induced immunosuppressed mice.