Abstract:Objective To study the roles of CD4+CD25+Foxp3+ regulatory T cells (Treg) and IL-33 in the pathogenesis of asthma in children. Methods Flow cytometry was used to detect peripheral blood CD4+CD25+Foxp3+Treg proportion in CD4+T lymphocytes in.45 children with asthma, 50 children with wheezing caused by respiratory syncytial virus infection and 40 healthy children. Serum levels of IFN-γ, IL-4, IL-5 and IL-33 were measured using ELISA. Results The level of peripheral blood CD4+CD25+Foxp3+Treg in the asthma group was significantly lower than in the wheezing and control groups (P<0.05). In contrast, serum levels of IL-33 in the asthma group was significantly higher than in the wheezing and control groups (P<0.05). Peripheral blood CD4+CD25+Foxp3+Treg level was negatively correlated with serum IL-33 level in the asthma group(r=-0.156, P<0.01). Conclusions CD4+CD25+Foxp3+Treg may interact with IL-33 in the pathogenesis of childhood asthma.