Objective To study the changes of the peripheral blood regulatory B cells and related cytokines in children patients with chronic idiopathic thrombocytopenic purpura (CITP),and to analyze their correlations with effective Th cells,and to discuss their roles in the pathogenesis of CITP.Methods The peripheral blood mononuclear cells (PBMC)were separated in 30 cases of CITP,then percentages of Th1 ,Th17,Th22 and Breg cells were detected by the flow cytometry(FCM).IFN-γ,IL-17,IL-22 and IL-10 levels in culture supernatant were measured by the ELISA method.Results Compared with the control group,the proportions of the peripheral blood Th1 ,Th17,Th22 subsets in CITP children were increased[(18.4±4.7)% vs.(10.82±4.4)%;(2.42±1.02 )% vs.(1 .23±0.42)%;(0.79±0.24)% vs.(0.26±0.11)%],the proportion of Breg cells was reduced significantly,the differ-ences had statistical significance[(0.83±0.21)% vs.(1 .89±0.12)%,P <0.05].In CITP children,the IFN-γ,IL-17,IL-22 levels in culture supernatant were higher than those in the control group[(278.2±121.2)pg/mL vs.(181.8 ±82.2)pg/mL;(214.8 ± 100.5)pg/mL vs.(161 .4±67.8)pg/mL;(122.16±22.2)pg/mL vs.(90.8±31.1)pg/mL],but the IL-10 level was lower than that in the healthy control group[(27.4±12.6)pg/mL vs.(46.1±16.2)pg/mL),differences between them had statistical signifi-cance(P <0.05).Besides,there was a positive correlation between the proportion of Breg cells and cytokine IL-10 level(r=0.617, P <0.05 ),however,there was a negative correlation between the proportion of Breg cells with Th1 ,Th17 and Th22 cells (P <0.05),between IL-10 level with IFN-γ,IL-17 and IL-22 levels(P <0.05).Conclusion The downregulation of Breg cells proportion may participate in the immune disorder mechanism of effective Th cells in CITP children,which can provide a new idea for the im-munoregulation therapy in CITP children.