Abstract:OBJECTIVE: To study the roles of CD4+CD25+ regulatory T cells and Foxp3 mRNA in peripheral blood as well as serum total immunoglobulin E (IgE) in the pathogenesis of bronchiolitis caused by respiratory syncytial virus (RSV). METHODS: The proportion of CD4+CD25+ regulatory T cells and expression of Foxp3 mRNA in peripheral blood, and total serum IgE level were tested by flow cytometry, RT-PCR and ELISA respectively in 57 children with RSV bronchiolitis (26 atopic patients and 31 nonatopic patients). Twenty five healthy children were used as the control group. RESULTS: The proportion of CD4+CD25+ regulatory T cells in peripheral blood in children with bronchiolitis, either in the atopic (7.7±1.6%)or the nonatopic group (8.8±2.1%), was significantly lower than that in the control group (10.5±1.6%) (P<0.01). Foxp3 mRNA expression in peripheral blood was significantly lower in both atopic and nonatopic children with bronchiolitis than that in the control group (P<0.01). Significantly increased total serum IgE level was noted in both atopic (241.2±102.5 IU/mL) and nonatopic children (125.5±63.2 IU/mL) with bronchiolitis compared with that in the control group (27.2±10.5 IU/ml) (P<0.01). There were significant differences in the proportion of CD4+CD25+ regulatory T cells and Foxp3 mRNA expression in peripheral blood (P<0.05) as well as total serum IgE level (P<0.01) between the atopic and the nonatopic group. The proportion of CD4+CD25+ regulatory T cells (r=-0.70, P<0.01) and Foxp3 mRNA expression in peripheral blood (r=-0.79, P<0.01) were closely negatively correlated to total serum IgE level. CONCLUSIONS: Both the proportion of CD4+CD25+ regulatory T cells and Foxp3 mRNA expression in peripheral blood were reduced, in contrast, the total serum IgE level increased in children with RSV bronchiolitis. This suggested that CD4+CD25+ regulatory T cells and Foxp3 mRNA together with IgE participated in the pathogenesis of RSV bronchiolitis.［Chin J Contemp Pediatr, 2009, 11 (5):349-353］
