Background 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 activity. Enzyme-linked immunosorbent assay (ELISA), a quantitative method to measure anti-type VII collagen antibody levels, is currently available to diagnose EBA.
Objective The aim of this study was to investigate the relationship of ELISA with overall clinical severity.
Methods Sera from patients with EBA (n = 30), bullous pemphigoid (n = 20), anti-laminin γ1 pemphigoid (n = 9) and healthy donors (n = 24) were tested using ELISA, using the recombinant non-collagenous 1 (NC1) and 2 (NC2) domains of type VII collagen. Relationships between clinical characteristics, indirect immunofluoroscence (IIF) titres and ELISA values were investigated.
Results The sensitivity and specificity of the EBA ELISA were 96.7% and 98.1%, respectively. There was no significant difference between ELISA results for classic and inflammatory types. The severity of skin involvement was positively correlated with both ELISA value (r = 0.87, P < 0.01) and IIF titre (r = 0.59, P < 0.01). Time sequence analysis in four patients with EBA showed that ELISA values reflect disease activity better than IIF titres.
Conclusions Type VII collagen ELISA using the NC1 and NC2 domains is useful for diagnosing EBA and monitoring disease severity.