Abstract: 　Objective　To explore the effects of atopy on the disease activity of juvenile idiopathic arthritis (JIA) in children and the role of Th17/Treg imbalance. Methods　Forty-seven JIA patients with atopy (atopic group), 64 patients with simple JIA (simple group) and 20 healthy control children (control group) were enrolled. The levels of IL-1β, IL-6, and IL17 in serum were detected by ELISA, the ratio of Th17 and Treg cells in peripheral blood lymphocytes was detected by flow cytometry, and the expressions of IL-17 and Foxp3 in peripheral blood mononuclear cells were detected by RT-q PCR. The differences in above indicators between the three groups were compared. Meanwhile, the difference of disease activity index between the two JIA groups was compared. Results　The serum levels of IL-1β, IL-6 and IL-17, the ratio of Th17 and Treg cells in lymphocytes and the expression levels of IL-17mRNA and Foxp3 mRNA were significantly different among control group, simple JIA group and atopic group (all P< 0.01). The serum levels of IL-1β, IL-6, and IL-17 in the atopic group and the simple JIA group were higher than those in the control group, and theywere higher in the atopic group than in thesimple group. The differences are statistically significant (all P<0.05). The percentage of Th17 cells in lymphocytes and the expression levels of IL17 mRNA were the highest in the atopic group and the lowest in the control group. The percentage of Treg cells in lymphocytes was the lowest in the atopic group and the highest in the control group. The platelet count, physician global assessment of disease activity (PGA), patient or parent global evaluation of well-being (PGE), children health assessment questionnaire (CHAQ), active joint count, restricted joint countand juvenile arthritis disease activity score (JADAS)-27 in atopic group were significantly higher than those in simple JIA group, and the difference was statistically significant (all P<0.05). Conclusion　Higher disease activity in JIA children with atopy may be related to increased IL-1β and IL-6 levels and Th17/Treg imbalance more toward Th17.

Key words: juvenile idiopathic arthritis;　atopy;　Th17/Treg