Immunoblot and immunoelectronmicroscopic analysis of endemic Tunisian pemphigus

Tunisian pemphigus is a newly described form of endemic pemphigus whose cli nical, histological and epidemiological characteristics have recently been detailed. The objective of this study was to analyse the binding properties of autoantibodies present in sera from patients with endemic Tunisian pemp higus using immunoblotting and indirect immunoelectron microscopy (IEM). Th irty patients with pemphigus foliaceus (PF) and six with pemphigus vulgaris (PV) seen in the dermatology department of Tunis Hospital between 1992 and 1994 were selected for this study. Seven of 30 (23%) and six of 12 (50%) P F sera tested bound to the 160 kDa band of desmoglein 1 when tested on bovi ne tongue and human epidermal extracts, respectively. Two of six and two of three PV sera tested bound to the 130 kDa desmoglein 3 in these two extrac ts. Immunoblot and indirect IEM showed that 24 of 30 (80%) PF sera containe d IgG1, IgG3 or IgG4 antibodies that bound to a 185-kDa polypeptide localiz ed on the desmosomal plaque. This immunological analysis showed that most e ndemic Tunisian pemphigus sera correspond to PF sera and are characterized by a high frequency of autoantibodies directed against a recently identifie d 185-kDa antigen of the desmosomal plaque.