Abstract: Yuan Huijie, Zhou Shengru, Liu Zhicui, Zhu Haiqin, Xu Renchao, 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 evaluate the specific antibody-producing capacity of locally infiltrating B lymphocytes in lesions of patients with pemphigus vulgaris （PV）. Methods Totally, 35 patients with PV and 22 healthy controls were enrolled into this study. Skin tissues were resected from blisters or erosions of the patients with PV, and from normal skin of healthy controls. Then, mononuclear cells were isolated from these skin tissues. Flow cytometry was performed to determine the percentages of lymphocytes, CD19+ B lymphocytes, and desmoglein （Dsg）1- and Dsg3-specific CD19+ B lymphocytes. B lymphocytes isolated from the lesional skin of patients with PV were cultured in vitro. Enzyme-linked immunosorbent assay （ELISA） was conducted to determine titers of anti-Dsg1 and anti-Dsg3 antibodies in the cell culture supernatant. Receiver operating characteristic（ROC）curve analysis was conducted to calculate positive rates of anti-Dsg1 and anti-Dsg3 antibodies. Results The percentages of lymphocytes （17.95% ± 3.85%） and CD19+ B lymphocytes （4.27% ± 1.13%） were significantly higher in the lesional skin of PV patients than in the normal skin of healthy controls （7.83% ± 1.29%, 0.61% ± 0.31% respectively; t = 2.49, U = 13.00 respectively, both P < 0.05）. Among the CD19+ B lymphocytes in the lesional skin of PV patients, the percentage of CD19+IgG+ B cells was （38.33 ± 5.56）%, and percentages of Dsg1- and Dsg3-specific CD19+ B lymphocytes were 12.87% ± 1.267% and 10.42% ± 1.243% respectively. After the in vitro culture for 6 days, the titers of anti-Dsg1 and anti-Dsg3 antibodies in the cell culture supernatant were （4.89 ± 1.56） U/ml and （35.45 ± 13.03） U/ml respectively, with their positive rates being 85%（17/20）and 95%（19/20）respectively. Conclusion There are Dsg1- and Dsg3-specific B lymphocytes aggregating in the lesional skin of patients with PV, which can produce anti-Dsg1 and anti-Dsg3 antibodies after in vitro culture.

Key words: Pemphigus, B-lymphocytes, Desmoglein 1, Desmoglein 3, Immunoglobulin G