Salt-split human skin substrate for the immunofluorescent screening of serum from patients with cicatricial pemphigoid and a new method of immunoprecipitation with IgA antibodies.

In patients with cicatricial pemphigoid, immunoglobulins (usually IgG) and complement are deposited within the dermoepidermal junction and are detected by direct immunofluorescent staining of perilesional mucous membrane and/or skin with fluorescein-labeled antibodies to human immunoglobulins. Although rare, some patients also have circulating low-titer, anti-basement membrane zone autoantibodies. In this study, we report 11 patients with the clinical, histologic, and immunologic criteria for cicatricial pemphigoid who had circulating anti-BMZ autoantibodies as demonstrated by positive indirect staining of a normal human skin that had been fractured through the dermoepidermal junction by prolonged incubation in a cold, 1 mol/L sodium chloride solution. On this salt-split human skin substrate, 9 of the 11 patients (82%) had autoantibodies that bound to the epidermal roof, one serum stained only the dermal floor, and one serum stained both sides of the separation. The predominant class of immunoglobulin in the patients' sera that bound to the substrate was IgA; IgA was the single immunoglobulin in 55% and was associated with IgG in 18%. IgG was the only immunoglobulin detected in 27% of the cases. No specific protein was detected by either Western immunoblot or a new IgA immunoprecipitation procedure.