Ultrastructural localization of Brazilian pemphigus foliaceus (fogo seivagem) antigens in cultured human squamous cell carcinoma cells

The ultrastructural localization of Brazilian pemphigus foliaceus (BPF) (fogo selvagem) antigen(s) in cultured human squamous cell carcinoma cells was studied using immunogold electron microscopy. Five of six BPF sera, which showed positive cell-surface reactivity on immunofluorescence, bound to the cell-cell contact area of cytoplasmic projections. This binding pattern was apparently different from that of non-endemic pemphigus foliaceus and pemphigus vulgaris sera, and mouse monoclonal anti-buman E-cadherin antibody. The results suggest tbat BPF autoantibodies recognize a molecule(s) which is different from non-endemic pemphigus antigens, or different epitope(s) of a molecule identical with non-endemic pemphigus antigens, and that the epitope(s) to which BPF autoantibodies bind is expressed on cell-cell contact areas at a relatively early stage of cell-cell adhesion formation.