Abstract: 【Abstract】 Objective To evaluate the value of indirect immunofluorescence （IIF） on three different substrates including normal human skin （NS）, monkey esophagus （ME） and salt?split human skin （SS） in the diagnosis of autoimmune subepidermal bullous diseases. Methods A total of 56 patients with autoimmune subepidermal bullous diseases, including 47 with bullous pemphigoid （BP）, 6 with epidermolysis bullosa acquisita （EBA）, 2 with linear IgA bullous dermatosis, and 1 with anti?P200 pemphigoid, were diagnosed in and enrolled from Department of Dermatology, Institute of Dermatology, Chinese Academy of Medical Sciences between January 2015 and December 2016. Seventy patients with pemphigus, 15 patients with chronic eczema and 15 healthy adults served as controls. Blood samples collected from these patients and controls were subjected to IIF on three different substrates including NS, ME and SS, and the fluorescence deposition was observed. The sensitivities and specificities of IIF in the diagnosis of different subepidermal bullous diseases were compared. Statistical analysis was carried out with SPSS 13.0 software by using chi?square test for the comparison of enumeration data. Results IIF on NS or ME in the serum of patients with BP showed linear deposition of fluorescent material along the basement membrane zone. IIF on SS showed linear deposition of fluorescent material in the epidermis in the patients with BP, but in the dermis in the patients with EBA and anti?P200 pemphigoid. The sensitivities of IIF on NS, ME or SS in the diagnosis of subepidermal bullous diseases were 73.2%, 60.7% and 94.6% respectively, and the specificities were 98.0%, 100% and 97.1% respectively. There were significant differences among the sensitivities （χ2 = 18.2, P < 0.05）, but no significant difference was observed among the specificities（P > 0.05）. The diagnostic sensitivity of IIF on SS was significantly higher than that of IIF on NS or ME（χ2 = 8.0, 16.7, both P < 0.05）. Conclusion In the diagnosis of autoimmune subepidermal bullous diseases, IIF on SS is superior to IIF on ME or NS.

Key words: Fluorescent antibody technique, indirect, Pemphigoid, bullous, Autoimmune subepidermal bullous disease, Diagnosis, Sensitivity, Specificity