Abstract: Liu Zhicui *, Yuan Huijie, Zeng Weihong, Zhang Chenxing, Wang Ying, Zheng Jie, Pan Meng. *Department of Dermatology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China Corresponding author: Pan Meng, Email: panmeng@medmail.com.cn 【Abstract】 Objective To investigate the activation state of and expressions of surface co-stimulatory molecules on peripheral CD4+ T cells from patients with pemphigus and healthy human controls. Methods Ninety patients with pemphigus including 24 patients with first-onset pemphigus, 51 with quiescent pemphigus and 15 with recurrent pemphigus, as well as 30 healthy human controls were enrolled in this study. Peripheral blood samples were obtained from these subjects followed by lymphocyte isolation. Flow cytometry was performed to detect the expressions of CD69, intercellular adhesion molecule-1（ICAM-1）, inducible co-stimulatory molecule （ICOS）, CD40 ligand （CD40L） and OX40 on CD4+ T cells. Statistical analysis was done by Mann-Whitney test using Graphpad 5.0 software. Results The expression rate of CD69 on peripheral CD4+ T cells from the healthy human controls was significantly lower than that from patients with pemphigus, patients with first-onset pemphigus, patients with quiescent pemphigus, and patients with recurrent pemphigus （（1.26 ± 0.19）% vs. （2.46 ± 0.19）%, （2.77 ± 0.40）%, （2.15 ± 0.25）% and （2.36 ± 0.35）%, all P < 0.05）. The patients with pemphigus also showed a significant increase in the expression rates of ICAM-1, CD40L and OX40 compared with the healthy human controls （（55.88 ± 1.67）% vs. （47.75 ± 2.52）%, P < 0.05; （2.23 ± 0.22）% vs. （0.73 ± 0.07）%, P < 0.01; （2.55 ± 0.29）% vs. （0.62 ± 0.17）%, P < 0.01）. No significant differences were observed between patients with different stages of pemphigus in the expression rates of CD69, ICAM-1, CD40L or OX40 （all P > 0.05）. The percentage of ICOS-expressing CD4+ T cells was significantly up-regulated in only patients with first-onset pemphigus as compared to the healthy controls （（3.73 ± 0.60）% vs. （2.39 ± 0.16）%, P < 0.05）. Conclusions The peripheral blood CD4+ T cells from patients with pemphigus are in a relatively active state with up-regulated surface expressions of many co-stimulatory molecules, suggesting that CD4+ T cells are involved in the initiation and progression of pemphigus by interacting with B cells through co-stimulatory molecules.

Key words: Pemphigus, T-lymphocytes, helper-inducer, Costimulatory molecule