Abstract: 【Abstract】 Objective To investigate clinical, immunoserological, and therapeutic characteristics of patients with linear IgA bullous dermatosis （LABD）. Methods Clinical data were collected from patients with LABD in Hospital of Dermatology, Chinese Academy of Medical Sciences from 2016 to 2023, and their clinical, immunoserological, and therapeutic characteristics were retrospectively analyzed. Results Twenty-six patients were included, comprising 12 males and 14 females, with a median age （Q1 , Q3） of 32 （11, 48） years. Among the 26 patients, 12 （46.2%） presented with annular erythema and blisters, while 14 （53.8%） with atypical lesions （erythema and blisters not in an annular arrangement）. Direct immunofluorescence assay yielded positive results in 14 out of 19 patients （73.7%）. Indirect immunofluorescence on salt-split skin showed IgA with or without IgG deposited in the epidermis of the salt-split skin in 53.8% （14/26） of the patients. The positive rate of IgA antibody detected by Western blot analysis was 88.5% （23/26）. Western blot analysis with epidermal extracts as substrates showed that 18 patients （69.2%） had serum IgA recognizing the linear IgA bullous dermatosis autoantigen LAD-1 with a relative molecular weight of 120 000, of whom 4 （15.4%） also had IgA recognizing BP180; in 1 case （3.8%）, the serum IgA could recognize a protein with a relative molecular weight of about 170 000 in the epidermal extracts; another 1 （3.8%） had IgA recognizing BP230 and a protein with a relative molecular weight of 140 000 in the epidermal extracts at the same time; additionally, the serum IgA recognizing type Ⅶ collagen with a relative molecular weight of 290 000 in the dermal extracts was detected in 1 case（3.8%）. Among 23 patients receiving dapsone treatment, 21 well responded, 1 showed poor response, and 1 was intolerant; in addition, the latter two patients could not achieve complete remission by tofacitinib. Minocycline, colchicine, and sulfasalazine were effective in another 3 patients. Conclusions In this study, LABD mainly occurred in middle-age individuals, and LAD-1 was determined to be a major autoantigen. Western blot analysis showed an increased positive rate of IgA antibody compared with immunofluorescence assay, and could be an important means of differential diagnosis. Although the LABD patients responded well to dapsone, it is still necessary to explore other safe and effective medications.

Key words: Skin diseases, vesiculobullous, Immunoglobulin A, Blotting, Western, Dapsone, Linear IgA bullous dermatosis