Abstract: Objective: To explore the effects of Pseudobulbus cremastrae seu pleiones polysaccharide (PCSPP) on the regulation of immune functionand the inhibition of tumor growth in sarcoma S180 tumor-bearing mice. Methods: Lymphocyte proliferation capacity and the phagocytic activity of spleen macrophages were determined by 3-(4,5-dimethyl- 2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide and neutral red methods; the effects of PCSPP on tumor growth, spleen index and thymus index in S180 tumor-bearing mice were evaluated through tumor suppression test in vivo, and the effects on T lymphocyte subgroup and serum cytokine levels were detected by flow cytometry and enzymelinked immunosorbent assay, respectively. Results: PCSPP could enhance lymphocyte proliferation capacity and macrophage phagocytic activity. PCSPP could inhibit tumor growth and increase spleen index and thymus index in S180 tumor-bearing mice; meanwhile, it could also increase the levels of CD4+ and CD8+ T cells in mice and elevate the CD4+/CD8+ ratio, interleukin-2, tumor necrosis factor-α and interferon-γ levels. Conclusion: PCSPP has a potent antitumor effect and its inhibitory effect may be related to ithe improvement of immune function.

Key words: Pseudobulbus cremastrae seu pleiones polysaccharide, sarcoma, immunoregulation, cytokines