Abstract: Astragalus membranaceus is a well-known traditional Chinese herbal medicine that has been used as a tonic herb in various immunodeficient diseases.In order to investigate the effects of astragalus polysaccharides (APS) on CD4⁺CD25⁺ regulatory T cells (CD4⁺CD25⁺ Treg) and CD4⁺Th17 cells in immunesuppressed mice,the immunesuppressed mouse models were established by intraperitoneal injection with cyclophosphamide.After the treatments with APS,the proportion of CD4⁺T cells or CD4⁺CD25⁺ Treg cells in spleen were analyzed by flow cytometry and the serum interleukin-17 (IL-17) factor was tested by enzyme-linked immunosorbent assay (ELISA).Compared with the model control mice,the proportion of CD4⁺ T cells obviously decreased and the proportion of CD4⁺CD25⁺ Treg cells significantly increased in mice of APS high-dose group and APS middle-dose group (P<0.05),and the level of serum IL-17 significantly reduced in mice of APS high-dose ［1.0 g/(kg·d)］ group (P<0.01).The results showed that APS can up-regulate the proportion of CD4⁺CD25⁺ Treg cells and inhibit the cytokine secretion of IL-17 in immunesuppressed mice.

Key words: Astragalus polysaccharides, immune suppression, CD4⁺CD25⁺ Treg cell, IL-17