Abstract: Objective To explore the influence of prostaglandin E2 on the immune function of CD4⁺CD25⁺ regulatory T cells. Methods CD4⁺CD25⁺ Tregs isolated from the spleens of male BALB/C mice were seeded on 96-well cell culture plates coated with anti-CD3 and soluble anti-CD28,and cells were stimulated with prostaglandin E2.According to the different concentrations of PGE2 stimulation,the cells were divided into four groups:control,A(7 μmol/L),B(14 μmol/L),and C(28 μmol/L) groups.The proliferation of cells,IL-10,IL-2 and expression of Foxp3 in Tregs were determined at various intervals. Results After being stimulated with PGE2 for 12 h,the proliferation of cells in A,B,and C groups had no significant difference(P>0.05),and IL-2,Foxp3 expression in B,C groups were respectively down-regulated and up-regulated markedly(P<0.05),and IL-10 levels in C group was markedly up-regulated(P<0.05) compared with control group.For 24 h,the proliferation of cells in B,C groups were significantly increased(P<0.05),IL-2 levels in A,B,and C groups were significantly down-regulated(P<0.05),but Foxp3 expression was increased(P<0.05),IL-10 levels in C group was markedly up-regulated(P<0.05).For 72 h,the proliferation of cells,IL-10 and Foxp3 expression in A,B,and C groups was markedly up-regulated(P<0.05),but IL-2 levels in three groups were significantly down-regulated(P<0.05). Conclusion These data indicate that PGE2 stimulation can directly strengthen immunosuppression function of Treg in vitro,which may further exert some regulating effect on the immune function of effector T cells.