Regulatory T cells and Th1/Th2 in peripheral blood and their roles in asthmatic children.

OBJECTIVE: To determine the changes in CD4(+)CD25(+)Foxp3(+) regulatory T cells (Treg) and the Th1/Th2 ratio in peripheral blood of children with asthma, in order to investigate its association with asthma. METHODS: A total of 150 children with asthma were allocated into the acute phase group (n=94) and remission phase group (n=56) based on clinical manifestations. The acute phase group was subdivided into the mild group (n=54) and severe group (n=40). Flow cytometry was applied to determine CD4(+)CD25(+)Foxp3(+) Treg, CD4(+)IFN-γ(+) Th1 and CD4(+)IL-4(+) Th2 levels in peripheral blood of different groups, and the results were compared with normal children (control group, n=50). RESULTS: The Treg level was significantly lower in the asthma group than the control group (P<0.01): the Treg level was significantly lower in the acute phase group than the remission phase group and control group (P<0.01) and also significantly lower in the severe group than the mild group (P<0.01). The Th1/Th2 ratio was significantly lower in the asthma group than the control group (P<0.01) and also significantly lower in the acute phase group than the remission phase group and control group (P<0.01). The Treg level in peripheral blood of asthmatic children was negatively correlated with the severity of asthma (r=-0.737, P<0.01) and the Th1/Th2 ratio was also negatively correlated with the severity of asthma (r=-0.615, P<0.01), but the Treg level was positively correlated with the Th1/Th2 ratio (r=0.856, P<0.01). CONCLUSIONS: The significantly decreased level of Treg in peripheral blood and Th subset imbalance in asthmatic children suggest the important roles of Treg and Th immunity in pathogenesis of asthma. The Treg level and Th1/Th2 ratio in peripheral blood can be used to evaluate the severity asthma.