Ultrastructural binding site of pemphigus foliaceus autoantibodies: comparison with pemphigus vulgaris

We studied in vivo binding sites of pemphigus foliaceus (PF) auto‐antibodies by immuno‐gold labelling technique, and compared them with those of pemphigus vulgaris (PV). In early acantholytic lesions of PF, the bound antibodies indicated by 5 nm protein A‐colloiclal gold particles were observed on the surface of keratinocytes, with particular affinity for desmosomes and separated attachment plaques. Nondesmosomal cell surfaces were sparsely labeled with the gold particles. A similar binding pattern was seen in the epidermal sheets obtained from a PV patient utilizing the Nikolsky phenomenon. These findings indicate that both PF and PV antigen‐antibody complexes are densely located on the desmosomal areas in early pemphigus lesions, suggesting the pathogenic importance of functional impairment of desmosomes by the autoantibodies.