Dynamic changes in Th17/Treg balance among children with seasonal allergic rhinitis
Objective 
To investigate the levels and significance of Th17 cells and regulatory T cells (Treg) in peripheral blood of children with allergic rhinitis during pollen and non-pollen seasons. 
 
 
Methods 
Thirteen children with hay fever, 10 children with house dust mite(HDM)-allergic asthma and 10 healthy children were recruited into this study. Percentages of Th17 and Treg cells were detected by flow cytometry. Levels of IL-17, IL-10 and TGF-β in cell culture supernatants were measured by ELISA. 
 
 
Results 
(1) The percentages of Th17 cells in children with allergic rhinitis [(3.4±2.4)%] were significantly higher than those in HDM-allergic asthmatics [(2.1±1.6)%] and those in healthy children [(0.5±0.3)%] during pollen season (both P<0.05). The levels of Treg cells in allergic rhinitis group [(2.1±1.3)%] and in HDM-allergic asthma group [(3.6±1.9)%] were significantly lower than those in healthy control group [(5.5±2.8)%] (both P<0.05). The levels of Th17 cells [(3.0±1.9)% vs (3.4±2.4)%, P<0.05] and ratios of Th17/Treg cells [(1.4±1.0)% vs (1.7±1.5)%, P<0.05] in children with allergic rhinitis were significantly decreased during non-pollen season as compared with those during pollen season, but the levels of Treg cells were up-regulated [(2.4±1.6)% vs (2.1±1.3)%, P<0.05]. (2) Correlation analysis revealed that the ratios of Th17/Treg cells were positively correlated with the concentrations of FeNO (fractional concentration of exhaled NO) (r=0.321, P<0.05) and the counts of circulating eosinophils (r=0.198, P<0.05) in children with allergic rhinitis during pollen season. 
 
 
Conclusion 
The imbalanced Th17 and Treg cells in children with allergic rhinitis during pollen season might play a vital role in the regulation of allergic airway inflammation. 
 
 
Key words: 
Allergic rhinitis; Bronchial asthma; Pollen; House dust mite; Th17 cell; Regulatory T cell