OBJECTIVE: To investigate immunomodulatory effects of Astragalus polysaccharides(APS) on the co-culture of peripheral blood mononuclear cells(PBMCs) with He La cervical cancer cell line.METHODS: To assess the proliferation of PBMCs,carboxyfluorescein succinimidyl ester(CFSE)-labeled PBMCs were co-cultured with He La cells and treated with different concentrations of APS. Supernatants of cell culture were collected for cytokines assay via enzyme-linked immunosorbent assay(ELISA). The impact of APS on the proliferation of PBMCs, induction of regulatory T cells(Tregs), and myeloid-derived suppressor cells(MDSCs) was carried out by flow cytometry.RESULTS: It was observed that APS could increase the proliferation of PBMCs co-cultured with He La cells(P < 0.05). However, APS had no significant effects on the induction of Tregs and MDSCs in the co-culture assay(P > 0.05). Furthermore, ELISA results demonstrated that APS could decrease IL-10 and TGF-β concentration(P < 0.05).CONCLUSION: The above-mentioned characteristics showed that APS might be able to modulate immune responses and improve anti-tumor effects through increasing the proliferation of PBMCs and decreasing inhibitory cytokines secretion as critical mediators of immune suppression in the tumor microenvironment.