Abstract: Liu Xiaojing, Xu Feng, Han Yumei, Sheng Youyu, Miao Ying, Hu Ruiming, Guo Xia, Qi Sisi, Yang Qinping. Department of Dermatology, Huashan Hospital, Fudan University, Shanghai 200040, China Corresponding author: Yang Qinping, Email: dxq93216@medmail.com.cn 【Abstract】 Objective To investigate the relationship of peripheral blood T helper type 17 （Th17） cells with the clinical course and severity of alopecia areata （AA）. Methods Peripheral blood samples were obtained from 60 patients with AA and 30 healthy human controls. Flow cytometry was performed to determine the proportion of Th17 subsets in these samples. Statistical analysis was done by two independent samples t-test with SPSS software version 16.0. Results The proportion of Th17 subsets in peripheral blood CD4+ T cells was significantly higher in the AA patients than in the healthy controls （1.33% ± 0.74% vs. 0.91% ± 0.54%, P ＜ 0.01）, higher in patients with initial AA than in those with recurrent AA （P ＜ 0.05）, higher in patients with active AA than in those with inactive AA （P ＜ 0.05）, higher in patients with a clinical course of < or = 6 months than in those > 6 months （P ＜ 0.01）. No significant difference was observed in the proportion of peripheral blood Th17 cells between patients with AA involving no more than 50% of the scalp and those with AA involving more than 50% of the scalp, alopecia totalis or alopecia universalis （P > 0.05）. Conclusion The level of peripheral blood Th17 cells is associated with the activity, relapse, and clinical course of AA.

Key words: Alopecia areata, Autoimmunity, Th17 cells