Objective:To explore the changes of T follicular regulatory (T FR) cells/T follicular helper (T FH) cells and their related cytokines in peripheral blood of children with dust mite allergic asthma, and their clinical significance. Methods:A total of 25 children with acute dust mite allergic asthma (the asthma group) in Affiliated Hospital of Jiangnan University from January to December 2021 and 16 age- and sex-matched healthy volunteers (the healthy control group) at the same time were enrolled in the retrospective study.The percentages of peripheral T FR cells and T FH cells of the 2 groups were measured by flow cytometry.The plasma levels of cytokines[interleukin (IL)-10, IL-21] of the 2 groups were assessed by the flow cytometric microsphere-based array technology.The specific IgE (sIgE) levels of dust mites in 2 groups were detected by fluorescence enzyme immunoassay.The percentage of eosinophils in peripheral blood detected by blood cell analyzer.Data between groups were compared by t-test, and the correlation among indicators was analyzed by Spearman rank correlation analysis. Results:The asthma group had evident T FR cells/T FH cells immune imbalance.Compared with the healthy control group, the asthma group had a significantly lower T FR cells level[(0.11±0.03)% vs.(0.13±0.03)%], a significantly higher T FH cells level[(5.07±1.75)% vs.(3.80 ± 1.60)%], and a significantly lower ratio of T FR cells /T FH cells(0.02±0.01 vs.0.05±0.03) ( t=2.29, 2.30, 3.71; all P<0.05). Compared with the healthy control group, the asthma group had a significantly higher IL-21 level[(547.85±195.13) ng/L vs.(404.94±110.41) ng/L], and a significantly lower IL-10 level[(10.18±3.49) ng/L vs.(14.79±5.65) ng/L] ( t=2.60, 3.15; all P<0.05). The ratio of T FR cells/T FH cells in asthma group was negatively correlated with sIgE ( r=-0.444 2, P=0.026 1), but not related to the eosinophil percentage ( r=-0.135 2, P=0.519 3). Conclusions:Children with dust mite allergic asthma suffer from T FR cells/T FH cells subset imbalance.The imbalanced T FR cells, T FH cells and their related cytokines IL-10 and IL-21 may play a role in regulating the production of asthma sIgE.