Recently, a previously unrecognized autoantibody mediated blistering disease, paraneoplastic pemphigus has been described. Paraneoplastic pemphigus is associated with lymphoid malignancies, thymomas, and poorly differentiated sarcomas. Serum of affected patients contain pathogenic autoantibodies that immunoprecipitate from normal keratinocytes a characteristic complex of four polypeptides with M, of 250, 230, 210, and 190 kD. As our preliminary studies indicated that the 250-kD and the 210-kD antigens comigrated with desmoplakins I and II, we investigated the possibility that autoantibodies against the desmoplakins were a component of this autoimmune syndrome. 11 sera from affected patients were tested by indirect immunofluorescence against desmosome containing tissues, immunoprecipitation of metabolically labeled keratinocytes, and Western immunoblotting of desmoplakins I and II that had been purified to homogeneity from pig tongue epithelium. By indirect immunofluorescence, 9 of 11 sera showed strong binding to epithelial and nonepithelial desmosomes, and 2 were weakly reactive. All 11 immunoprecipitated 250-and 210-kD bands of variable intensity that comigrated with bands identified by a murine monoclonal antidesmoplakin antibody, and immunoblotting confirmed binding of the serum autoantibodies to purified desmoplakins. This demonstrates that paraneoplastic pemphigus is the first human autoimmune syndrome in which autoantibodies against the desmoplakins are a prominent component of the humoral autoimmune response. (J. Clin.
We reviewed the clinical, histologic, and immunofluorescence features of 20 patients with pemphigus and neoplasia and compared them with a control group of 17 patients with pemphigus without neoplasia. Patients with neoplasia were divided according to clinical, histologic, and immunofluorescence findings into those with paraneoplastic pemphigus syndrome (12 patients) and those with classic pemphigus vulgaris or pemphigus foliaceus with neoplasia (8 patients). The histologic findings in patients with paraneoplastic pemphigus included acantholysis, interface dermatitis, spongiosis, and satellite keratinocyte necrosis. Histologic findings in the 8 patients with classic pemphigus and neoplasia included acantholysis and spongiosis. Direct immunofluorescence in both paraneoplastic pemphigus and pemphigus with neoplasia showed IgG staining of cell-surface proteins (intercellular substance) and deposition of immunoglobulin at the basement membrane zone. Indirect immunofluorescence with rat bladder substrate was used to differentiate paraneoplastic pemphigus from classic pemphigus. Circulating IgG anti-cell-surface protein antibodies were detected in 4 patients with paraneoplastic pemphigus syndrome; they were absent in 2 patients with pemphigus and neoplasia. Immunoprecipitation of sera from the 4 patients with epithelial staining showed the complex of bands identified in studies of paraneoplastic pemphigus syndrome. We conclude that paraneoplastic pemphigus syndrome has distinct clinical, histologic, and immunologic features that differentiate it from classic pemphigus with underlying neoplasia.
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