Abstract: Zhang Xiaoting, Li Shuifeng, Zhao Ying, Ye Yanting, Qi Shiling, Yang Yuqing, Cao Hui, Zhang Xingqi *. *Department of Dermatology and Venereology, First Affiliated Hospital, Sun Yat-sen University, Guangzhou 510080, China Corresponding author: Zhang Xingqi, Email: xingqi.zhang@hotmail.com 【Abstract】 Objective To analyze the quantity and distribution of Langerhans cells in lesions of alopecia areata （AA）, so as to investigate their role in the pathological process of AA as well as their relationship with T lymphocytes. Methods Tissue specimens were obtained from the scalp lesions of AA in 29 patients, including 16 in active phase and 13 in non-active phase. All the specimens were subjected to immunohistochemical staining for CD1a, and 17 specimens to immunohistochemical staining for CD4 and CD8. Fluorescence-based semi-quantitative reverse transcription （RT）-PCR was performed to determine the mRNA expressions of CD1a and granulocyte-macrophage colony stimulating factor （GM-CSF） in the full-thickness skin specimens. Statistical analysis was done using Mann Whitney U test and Pearson correlation analysis. Results There was a significant increase in the quantity of CD1a+ Langerhans cells in the epidermis, perivascular and perifollicular areas in the upper and deep dermis of the AA patients compared with the healthy controls （Z = 4.354, 2.884, 4.640, 3.217, 3.496, all P ＜ 0.01）, and in the epidermis, perivascular and perifollicular areas in the deep dermis of AA patients in active phase compared with those in non-active phase （Z = 2.457, 2.130, 1.954, P < 0.05 or = 0.05）. The relative mRNA expression levels of CD1a and GM-CSF in the patients were similar to the healthy controls in the upper dermis, but significantly higher than the healthy controls in the deep dermis （Z = 2.702, 2.941, both P < 0.01）. A positive correlation was observed between the quantity of perivascular Langerhans cells in the upper dermis and that of perifollicular CD8+ T lymphocytes in the deep dermis in patients with AA （r = 0.618, P < 0.05） and in patients with active AA （r = 0.795, P = 0.01）, but not in patients with inactive AA （r = 0.304, P > 0.05）. Conclusions The number of Langerhans cells is elevated in patients with AA, especially in patients with active AA. The quantity of perivascular Langerhans cells in the upper dermis is positively correlated with that of perifollicular CD8+ T lymphocytes in the deep dermis of active AA lesions, hinting that Langerhans cells play an important role in the progression of AA.

Key words: Alopecia areata, Langerhans cells, T-lymphocytes, CD1a protein