Detection of Anti‑basement membrane zone antibodies in the blister fluid in subepidermal autoimmune bullous diseases

Background: Subepidermal autoimmune bullous diseases (sAIBD) are diverse of conditions with clinicopathological overlap. Circulating autoantibodies in the serum can be demonstrated using indirect immunofluorescence (IIF) microscopy. Artificially split normal human skin is considered as an optimum substrate for the demonstration of anti-basement membrane zone (BMZ) antibodies using IIF in sAIBD; it not only helps to detect the presence of circulating antibodies in the serum but also helps to subclassify these conditions into “roof” and “floor” binding disorders. Aim: In this study, we evaluated the utility of IIF to detect anti-BMZ antibodies in the blister fluid of patients with sAIBD. Materials and Methods: Twenty-two patients with a clinical diagnosis of sAIBD were enrolled in the study. IIF of serum and blister fluid were done simultaneously using salt-split skin as a substrate. Results: Anti-BMZ antibodies could be detected in the blister fluid using IIF in all patients in the study group. Limitation: We could not do enzyme-linked immunosorbent assay of blister fluid. This would have given us the quantitative data of circulating antibodies in the blister fluid. Conclusion: Blister fluid offers an alternate source for the detection of autoantibodies in patients with sAIBD. It may be of particular help in children and in elderly with poor venous access.