Abstract: This study investigates the anti-tumor effect of Radix Isatidis polysaccharide (RIP) on tumor bearing mice and its influences on immune function.The impacts of RIP were observed by transplanted tumor and ascites tumor within S₁₈₀ mice,and cyclophosphamide was used as the positive control.After 12 days of continuous administration,the tumor weight,inhibition rate of tumor growth,spleen and thymus index,splenic lymphocyte transformation function,killing activity of NK cells,the levels of TNF-α,INF-γ,IL-2 in serum were detected.HE staining and cell cycle analysis were performed on the tumor tissue.The ascites tumor mice followed up for the same dosing period were fed normally afterwards,and the time of natural death of each group was recorded.The results showed different doses of RIP can all obviously inhibit the growth of tumor in mice,especially the 100 mg/kg and 50 mg/kg group with the inhibition rates of 35.4% and 38.5%.The spleen index and thymus index of the transplanted mice in each dose group were significantly higher than those of the control group.It also stimulated the proliferation of splenic lymphocytes,enhanced the killing activity of NK cells,and increased the levels of TNF-α,INF-γ,and IL-2 in serum,the 50 mg/kg group compared with the blank control group was statistically significant (P<0.01).The analysis of HE staining showed that the tumor necrotic area in each dose group was increased in different proportion.Flow cytometry showed that the proportion of G₀ /G₁ phase cells increased,the proportion of S phase cells decreased,G₂/M phase cells did not change significantly.It suggested RIP has anti-tumor effect and can enhance the immune function and prolong the survival time of tumor-bearing mice.

Key words: Radix isatidis polysaccharide, S₁₈₀, anti-tumor, immunoregulation, mice