摘要Objective:To investigate whether kynurenine/aryl hydrocarbon receptor (AHR) affects the maternal-fetal tolerance by involving the differentiation of T helper 17 (Th17)/regulatory T (Treg) cells, and to provide theoretical basic for new treatment of unexplained abortion.Methods:Flow cytometry (FCM) was used to detect the expression of AHR in peripheral/decidual CD4+ T, Treg, and Th17 cells.The effect of Kyn on the differentiation ofperipheral/decidual na(i)ve T-cells under Treg-/Th17-polarizing condition was detected by FCM;enzyme-linked immunosorbent assay was performed to examine the level of Kyn in villus and decidual tissues from normal pregnancy (NP) and unexplained abortion (UA).Student's t-test in the case of two groups or one-way ANOVA in multiple groups was used.Results:AHR expression in CD4+ T-cells was decreased in decidua versus blood in early pregnancy (P ＜ 0.0001).Kyn could promote the differentiation of peripheral and decidual na(i)ve T-cells to Th17 cells under Treg-polarizing conditions (P ＜ 0.01).There was no statistical significance about the concentration of Kyn in decidual or villi tissues between NP and UA, and compared with NP, the expression of AHR in decidual CD4+ T-cells from UA was increased (P ＜ 0.001).Conclusions:Kyn/AHR promotes Th17 and restricts Treg cells' differentiation, which is involved in maintaining the balance ofTreg/Th17 cells at the maternal-fetal interface.