Identification of a new antibody population directed against a desmosomal plaque antigen in pemphigus vulgaris and pemphigus foliaceus

Pemphigus vulgaris and pemphigus foliaceus are characterized by autoantibodies directed against transmembrane glycoproteins of desmosomes. F12, a human monoclonal autoantibody that binds to the desmosomal plaque, recognizes a 180-190-kDa doublet when immunoblotted against bovine tongue epithelium. Because F12 was derived from the peripheral blood lymphocytes of a patient with pemphigus vulgaris, we looked for the presence of anti-180-190-kDa antibodies in pemphigus vulgaris and pemphigus foliaceus serum. By immunoblot analysis, a third of the pemphigus serum contained anti-180-190-kDa antibodies that belonged to IgG subclass 1 or 3, unlike those that recognized desmogleins 1 and 3 (IgG4). By immunoelectron microscopy analysis on human oral mucosa and human skin with mAb to human IgG3, pemphigus serum containing anti-180-190 kDa antibodies recognized desmosomal plaques. The presence of antibodies with F12 properties in pemphigus serum was further demonstrated by a rabbit anti-F12 idiotype antiserum that allowed detection of F12 idiotype in serum with anti-180-190-kDa antibodies. These results indicate that some pemphigus vulgaris and pemphigus foliaceus serums contain antibodies that react with both intra- and extracellular structures of desmosomes and further demonstrate the heterogeneity of the autoimmnne response in both types of pemphigus.