BINDING OF AUTOANTIBODIES IS NOT RESTRICTED TO DESMOSOMES IN PEMPHIGUS-VULGARIS - COMPARISON OF 14 CASES OF PEMPHIGUS-VULGARIS AND 10 CASESOF PEMPHIGUS FOLIACEUS STUDIED BY WESTERN IMMUNOBLOT AND IMMUNOELECTRON MICROSCOPY

Pemphigus vulgaris (PV) and pemphigus foliaceus (PF) are autoimmune bl istering diseases characterized by a Loss of cell-cell adhesion and by autoantibodies directed against epidermal cadherins, PF antigen has b een established as desmoglein I which is located strictly on the desmo some, whereas the precise ultrastructural localization of PV antigen r emains unclear and controversial to date. To further investigate this question, we compared the location of immune deposits in 14 patients w ith PV and 10 patients with PF by both direct and indirect immunoelect ron microscopy (IEM). Inclusion criteria were based upon clinical feat ures, histological level of cleavage and characterization of circulati ng antibodies by Western blot on epithelial bovine tongue extracts, IE M was performed on unfixed 0.7-mm slices of skin for the direct techni que or on normal skin for the indirect technique using peroxidase labe lling. In PF, by both direct and indirect IEM, immune deposits were lo cated on the extracellular part of desmosomes (desmoglea) in all the s amples studied, In PV, by both direct and indirect IEM, deposits were situated on the desmoglea and along large portions of the keratinocyte membrane without desmosomal structures in 15 of the 18 samples studie d and only on the desmoglea in 3 samples. These results suggest that, in contrast to PF, the target antigen in PV is not always restricted t o desmosomes. As various types of adherens junctions have been reporte d to mediate cell adhesion in the epidermis, the PV antigen could be a component of desmosomes and of other focal adhesions.