OBJECTIVETo investigate the changes of CD4+CD25+Foxp3+ regulatory T cells (Treg) and T helper cells (Th1/Th2) in peripheral blood and their roles in the severity evaluation in children with asthma.

METHODSOne hundred and fifty children with asthma were classified into acute attack (94 cases) and remission (56 cases) groups according to their clinical features, and the acute attack children were subdivided into mild asthma (54 cases) and severe asthma (40 cases) groups. Fifty healthy children were enrolled as a control group. The levels of CD4+CD25+Foxp3+ Treg, CD4+IFN-γ+ Th1 and CD4+IL-4+ Th2 in peripheral blood were measured by flow cytometer.

RESULTSThe mean levels of CD4+CD25+Foxp3+ Treg and the ratio of Th1/Th2 in asthmatic children were lower than those in the control group (P<0.01). The Treg levels and the ratio of Th1/Th2 in the acute attack group were lower than those in the remission group and in the control group (P<0.01). The Treg levels in the severe asthma group were lower than those in the mild asthma group (P<0.01). There was a remarkably negative correlation between Treg levels and the asthma severity (r=-0.737, P<0.01), and the Th1/Th2 ratio was also negatively correlated with the asthma severity (r=-0.615, P<0.01). The Treg levels were positively correlated with the Th1/Th2 ratio (r=0.856, P<0.01).

CONCLUSIONSThe Treg levels decrease remarkably and Th subsets imbalance occurs in children with asthma. This suggests that Treg and Th immunity play important roles in the pathogenesis of asthma. The Treg levels and the ratio of Th1/Th2 in peripheral blood may be useful in the evaluation of severity in children with asthma.