Frequencies of Serum IgA Autoantibodies and IgA-associated Clinical Features in Pemphigus, Bullous Pemphigoid and Epidermolysis Bullosa Acquisita

Lee, Chang Woo; Shin, Young Ik

Abstract

BACKGROUND: Pemphigus (P; pemphigus vulgaris, PV; pemphigus foliaceus, PF), bullous pemphigoid (BP) and epidermolysis bullosa acquisita (EBA) are autoimmune blistering skin diseases induced by IgG autoantibodies. In some cases of these diseases IgA autoantibodies can be detected at the lesional skin as well as in the sera. OBJECTIVE: The aims of this study were to examine the frequencies of circulating disease-specific IgA autoantibodies in addition to IgG, in P, BP and EBA; possible clinical relevancies in connection with the presence of IgA autoantibodies in the sera were also reviewed with the patients in each disease. PATIENTS/METHODS: Twenty new patients of the individual diseases who showed positive indirect immunofluorescence findings of IgG were selected. Immunoblotting and multi-step immunostaining were performed ('amplified alkaline phosphatase immunoblot' preparations [Bio-Rad BRL]) with patients' sera using tissue antigens of A431 cell culture-extracts. RESULTS: Among the above 20-patient groups in P, 7 cases (PV 3, PF 4) were positive for serum IgA autoantibodies. In BP and EBA, 4 cases and 16 cases were positive for circulating IgA autoantibodies, respectively. Between the positivity-rate found in each category, patients with EBA showed a significant high positive frequency of 80% as compared with others having P or BP (p>0.045). There were no statistically significant clinical correlations between the serologic findings of IgA-positivities and the clinical expressions of the diseases including mucous membrane involvements in each disease (p>0.3). CONCLUSIONS: The frequency-rates of dual expressions of autoantibodies, IgG and IgA, were relatively lower in patients with P (35%) and BP (20%) than those patients with EBA showing a significant high rate (80%). Clinical relevancies with the presence of serum IgA autoantibodies were not seen in this study, perhaps indicating further immunopathological and clinical evaluations might be necessary to define the role of IgA autoantibodies in each disease.