Drug-induced pemphigus: autoantibodies directed against the pemphigus antigen complexes are present in penicillamine and captopril-induced pemphigus

Pemphigus is an autoimmune blistering disease characterized by circulating autoantibodies directed against the keratinocyte cell surface. The two variants, pemphigus foliaceus and pemphigus vulgaris, can be distinguished at the molecular level by immunochemical studies. The large majority of patients with pemphigus develop the disease spontaneously; however, there is a small group of patients who develop pemphigus after treatment with certain medications, of which penicillamine and captopril are the best documented. Most patients with drug-induced pemphigus have circulating and/or tissue bound epidermal cell surface autoantibodies; however, the molecular specificity of these autoantibodies has not been studied. We performed immunoprecipitation studies utilizing extracts of 125I-labeled suction blister epidermis and the sera of three patients with drug-induced pemphigus foliaceus (two due to penicillamine and one due to captopril) and one patient with captopril-induced pemphigus vulgaris. We found that the three patients with drug-induced pemphigus foliaceus had circulating autoantibodies that are directed against the pemphigus foliaceus antigen complex and that the one patient with drug-induced pemphigus vulgaris had circulating autoantibodies that are directed against the pemphigus vulgaris antigen complex. This study demonstrates that autoantibodies from drug-induced pemphigus patients have the same antigenic specificity, on a molecular level, as do autoantibodies from other pemphigus patients.