Abstract:

Objective To determine the protein and mRNA expression levels of interleukin-l7 （IL-17） and proportions of Th17 cells in peripheral blood of patients with atopic dermatitis（AD）, and to analyze their clinical significance． Methods Venous blood samples were obtained from 63 patients with AD and 30 normal human controls. Enzyme linked immunosorbent assay was performed to measure the plasma level of IL-17 protein, real time fluorescence reverse transcription （RT）-PCR to detect the mRNA expression level of IL-17 in peripheral blood, flow cytometry to determine the percentage of Th17 cells in peripheral blood mononuclear cells （PBMCs）. Spearman′s rank correlation analysis was performed to assess the relationship of peripheral blood Th17 cell percentage and IL-17 levels with disease severity in patients with AD. Results The percentage of Th17 cells in PBMCs was 1.83% ± 0.47% in patients with acute AD, significantly higher than that in normal human controls （0.85% ± 0.45%，t = 4.128，P < 0.01） and in patients with chronic AD （1.12% ± 0.69%，t = 2.439，P < 0.05）. There was a significant increase in the plasma level （98.37 vs. 63.75 ng/L, U = 168, P < 0.05） and mRNA expression level of IL-17 in peripheral blood in patients with AD compared with normal controls. Both the Th17 cell percentage and plasma IL-17 level were positively correlated with eczema area and severity index （EASI） score in patients with AD（r = 0.68l，P < 0.01；r = 0.427，P < 0.05）. Conclusions There is an elevated proportion of Th17 cells and an abnormal expression of IL-17 protein and mRNA in peripheral blood from patients with acute AD, which are positively correlated with disease severity, implicating the possible roles of IL-17 and Th17 cells in the pathogenesis of AD.

Key words: Helper T(Th)cell l7