Objective: To investigate the effects of astragalus polysaccharide(APS) on regulatory T cells (Treg) in tumor-bearing mice. Method: Mice were subcutaneously implanted with B16-F10 cells in the right back region. Then these mice were randomly divided into model group

cyclophosphamide(CTX) group

APS low dose group (0.15 g·kg-1)

APS high dose group (0.3 g·kg-1). Another ten normal mice were used as normal control. After 24 h

intragastric administration was performed. After 14 days of intragastric administration

tumors were removed and weighed

Treg of spleen were detected by flow cytometer(FCM)

mRNA expression of transforming grwoth factor-β(TGF-β) and interleukin-10(IL-10) in spleen was measured by real-time PCR. Result: The results showed that APS could inhibit the B16-F10 tumor growth

reduce the proportion of Treg in spleen(P<0.01)

decrease mRNA expression of TGF-β and IL-10 in spleen(P<0.05). Conclusion: The results indicated that APS might inhibit tumor growth partly by reducing the proportion of Treg in spleen and decreasing mRNA expression of TGF-β and IL-10 in spleen.