Abstract: Objective:To investigate the role and significance of Th17/Treg and its related cytokine levels in the pathogenesis of wheezing in infants.Methods:Sixty acute attack wheezing infants,50 lower respiratory infection infants without wheezing and 50 healthy infants were divided into the wheezing group,nonwheezing group and control group,respectively.According to the number of wheezing,the wheezing group was subdivided into the group A1(first wheezing group,34 cases) and group A2(repeat wheezing group,wheezing number ≥ 2 times,26 cases).According to the risk factor of wheezing,the wheezing group was subdivided into the group B1(complicated with high risk factor group,25 cases) and group B2(complicated without high risk factor group,35 cases).The proportions of Th17 and Treg cells in peripheral blood in all groups were detected using flow cytometry,and the serum levels of interleukin-17(IL-17) and interleukin-10(IL-10) in all group were detected using ELISA.Results:The differences of the percentages of Th17 and Treg cells,and Treg/Th17 between three groups were statistically significant(P<0.01).The Treg cells and percentage of Treg/Th17 in wheezing group and nonwheezing group were significantly lower than those in control group(P<0.01),and the percentage of Th17 cells in wheezing group and nonwheezing group were significantly higher than that in control group(P<0.01).The Treg cells and percentage of Treg/Th17 in wheezing group were significantly lower than those in nonwheezing group(P<0.01),and the percentage of Th17 cells in wheezing group was significantly higher than that in nonwheezing group(P<0.01).The differences of the serum levels of IL-17 and IL-10 between three groups were statistically significant(P<0.01).The serum levels of IL-17 in wheezing group and nonwheezing group were significantly higher than that in control group(P<0.01),and the serum levels of IL-10 in wheezing group and nonwheezing group were significantly lower than that in control group(P<0.01).The serum level of IL-17 in wheezing group was significantly higher than that in nonwheezing group(P<0.01),and the serum level of IL-10 in wheezing group was significantly lower than that in nonwheezing group(P<0.01).The percentage of Th17 cells in group A1 was higher than that in group A2(P<0.01),the Treg cells and percentage of Treg/Th17 in group A1 were significantly lower than those in group A2(P<0.01).The IL-17 level in group A1 was significantly higher than that in group A2(P<0.01),and the IL-10 level in group A1 was significantly lower than that in group A2(P<0.01).The percentage of Th17 cells in group B1 was significantly higher than that in group B2(P<0.01),and the Treg cells and percentage of Treg/Th17 in group B1 were significantly lower than those in group B2(P<0.01).The IL-17 level in group B1 was significantly higher than that in group B2(P<0.01),and the IL-10 level in group B1 was significantly lower than that in group B2(P<0.01).Conclusions:Early detection of Th17/Treg and related cytokines in peripheral blood may provide the basis of early diagnosis and intervention for children with bronchial asthma development tendency.