Serum Levels of Anti-Type VII Collagen Antibodies Detected by Enzyme-Linked Immunosorbent Assay in Patients with Epidermolysis Bullosa Acquisita are Correlated with the Severity of Skin Lesions

Abstract

Epidermolysis bullosa acquisita (EBA) is a chronic autoimmune subepidermal bullous disease characterized by circulating autoantibodies against type VII collagen. Detecting these autoantibodies is crucial for the diagnosis of this disease, and is also useful for measuring disease severity. Enzyme linked immunosorbent assay (ELISA), a quantitative method to measure anti-type VII collagen antibody levels, is currently available to diagnose EBA. The aim of this study was to validate the usefulness of type VII collagen ELISA in diagnosing EBA and monitoring disease severity. Sera from patients with EBA (n=30), bullous pemphigoid (n=20), anti-laminin γ1 pemphigoid (n=9), and healthy donors (n=24) were tested by ELISA using the recombinant noncollagenous 1 (NC1) and 2 (NC2) domains of type VII collagen. Relationships between clinical characteristics, indirect immunofluoroscence (IIF) titers and ELISA values were investigated. The sensitivity and specificity of the type VII collagen ELISA were 96.7% and 98.1%, respectively. There was no significant difference between ELISA results for classic and inflammatory types (72.6 vs. 47.4 U/ml, p=0.15). The severity of skin involvement was positively correlated with both ELISA index value (r=0.87, p<0.01) and IIF titer (r=0.59, p<0.01). Time sequence analysis in 4 patients with EBA showed that ELISA index values reflect disease severity better than IIF titers. Type VII collagen ELISA using the NC1 and NC2 domains is useful for diagnosing EBA and monitoring disease severity.