Abstract: Objective To research the impact of APE1 overexpression on the immune function of CD4⁺CD25⁺Treg cells with the stimulation of PGE2 in vitro. Methods We collected BALB/C mice,isolated and cultured CD4⁺CD25⁺Treg cells,constructed APE1 overexpression lentivirus vector and transfected into CD4⁺CD25⁺Treg cells,establish APE1 overexpression of CD4⁺ CD25⁺Treg cells,as the experimental group cells;the empty vector lentiviral vectors were transfected into the same amount of CD4⁺CD25⁺Treg cells,as the control group.In vitro,two groups were stimulated by PEG2 for 72 h,IL-10,TGF-βand APE1 mRNA levels were tested,the results were analyzed using t-test,P＜0.05 was considered statistically significant. Results The APE1 gene lentiviral vector was constructed,APE1 gene lentiviral vector transfected the CD4⁺CD25⁺Treg successfully.After stimulation with PGE2 to transfected APE1 overexpressed CD4⁺CD25⁺Treg and empty vector transfected CD4⁺CD25⁺Treg in vitro,The levels of TGF-β and IL-10 (1.17±0.42,1.02±0.12) were significantly lower in transfected APE1 overexpressed CD4⁺CD25⁺Treg group as compared with the other group of cells(2.69±0.21,2.25±0.31),all with statistical significance;APE1 mRNA relative expression was significantly higher in APE1 overexpressed CD4⁺CD25⁺Treg(6.57±0.49) than the other group(2.24±0.23),with significant difference;APE1 protein expression also showed the same results. Conclusion PGE2 stimulation can result in the expression of APE1 of CD4⁺CD25⁺Treg cells,and decline the immunosuppression function of the CD4⁺CD25⁺Treg,which may be related to the downregulation of IL-10 and TGF-β.