Abstract: Sun Yi, Wang Zhenhua. Department of Dermatology, Weifang People′s Hospital, Weifang 261041, Shandong, China Corresponding author: Wang Zhenhua, Email: wfzcwzh@126.com 【Abstract】 Objective To investigate the role of interleukin-22 （IL-22） in the pathogenesis of pityriasis rosea （PR）． Methods Peripheral venous blood samples were obtained from 48 patients with PR in acute stage and recovery stage and from 20 healthy human controls. Real-time fluorescence-based quantitative PCR was performed to measure the mRNA expression of IL-22 in peripheral blood mononuclear cells （PBMCs）, and enzyme-linked immunosorbent assay （ELISA） to determine the level of IL-22 in sera. Results The relative expression level of IL-22 mRNA in the patients with PR in recovery stage was significantly higher than that in the healthy controls （2.89 ± 0.91 vs. 1.91 ± 0.60, t = 3.84, P < 0.05）, but lower than that in the patients in acute stage （2.89 ± 0.91 vs. 4.15 ± 1.36, t = 3.61, P < 0.05）. Similarly, the level of serum IL-22 was significantly increased in the patients with PR in recovery stage compared with the healthy controls （（21.44 ± 7.33） vs. （13.22 ± 4.26） ng/L, t = 4.49, P < 0.05）, and increased in the patients with PR in acute stage compared with those in recovery stage （（36.87 ± 10.63） vs. （21.44 ± 7.33） ng/L, t = 5.01, P < 0.05）. The level of serum IL-22 was positively correlated with the stage of PR （r = 0.883, P < 0.05）. Conclusions IL-22 is overexpressed in PBMCs and sera of patients with PR, implying that IL-22 is involved in the pathogenesis of PR．

Key words: Pityriasis rosea, Interleukin-22, Pathogenesis