Abstract: Su Huichun, Sun Jing, Luo Yang, Han Yue, Liu Xiaochun, Zhang Jingxi, Wen He, Yao Xu, Wang Baoxi Department of Allergy and Rheumatology, Institute of Dermatology, Chinese Academy of Medical Sciences and Peking Union Medical College, Nanjing 210042, China （Su HC［current affiliation: Department of Dermatology, The First Affiliated Hospital of Fujian Medical University, Fuzhou 350004, China］, Sun J［current affiliation: Department of Dermatology, Peking University People′s Hospital］, Luo Y, Han Y, Liu XC, Zhang JX, Wen H, Yao X）; Department of Dermatology, Plastic Surgery Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100144, China （Wang BX） Corresponding authors: Yao Xu, Email: dryao xu@126.com; Wang Baoxi, Email: wangbx@ncstdlc.org 【Abstract】 Objective To detect the serum level of transglutaminase 2 （TG2）?specific IgE （sIgE） in patients with atopic dermatitis （AD）, and to analyze its correlation with the disease condition. Methods A total of 77 patients with AD were enrolled into this study, including 44 patients aged ≥ 12 years and 33 patients aged < 12 years. Of the 77 patients, 20 were diagnosed with intrinsic AD, which was characterized by the absence of sIgE and total serum IgE values < 150 kU/L, and 49 with extrinsic AD characterized by positive （++） or even strongly positive sIgE for more than 1 kind of exogenous allergens, or total serum IgE values ≥ 150 kU/L. Immunocapture?biotinylated detector enzyme immunoassay was performed to detect the serum level of TG2?sIgE in 77 patients with AD, 40 adult patients with psoriasis vulgaris （PV） and 30 healthy adult controls. Clinical data on the AD patients were recorded, including age, disease duration, SCORAD score, blood eosinophil count, levels of total IgE and TG2?sIgE. Results The serum levels of TG2?sIgE in AD patients aged ≥ 12 years, AD patients aged < 12 years, PV patients and healthy controls were 1.02 ± 0.2, 1.04 ± 0.044, 0.93 ± 0.25 and 0.71 ± 0.13, respectively. Additionally, the serum level of TG2?sIgE significantly differed among AD patients aged ≥ 12 years, PV patients and healthy controls （χ2 = 37.407, P < 0.001）, and was significantly higher in both AD patients aged ≥ 12 years and PV patients than in the healthy controls （t = 7.38, 4.83, respectively, both P < 0.001）. Moreover, the intrinsic AD group showed significantly higher TG2?sIgE levels compared with the extrinsic AD group （1.16 ± 0.03 vs. 1.02 ± 0.20, t = 2.27, P = 0.02）. The TG2?sIgE level was uncorrelated with the patients′ age, disease duration, SCORAD score, blood eosinophil count or serum total IgE levels in AD patients （r = 0.03, 0.14, -0.04, -0.08, 0.06, respectively, all P > 0.05）. Conclusion The serum level of TG2?sIgE obviously increases in AD patients, so TG2 may be one kind of autoantigen in AD patients, but there is no significant correlation between the TG2?sIgE level and AD severity.