Biochemical differentiation of types of pemphigus

There are two major types of pemphigus as determined by clinical and histologic criteria: PV, in which the blister forms at the suprabasilar layer of the epidermis, and PF, in which the blister forms in the more superficial epidermis. The autoantibodies from both types of pemphigus bind in an identical fashion to the cell surface of keratinocytes. Blocking studies suggest that PF and PV sera recognize different epidermal antigens. Absorption studies have suggested that a variety of antigens react with pemphigus autoantibodies, but the conditions of these studies may have absorbed or inactivated the antibodies nonspecifically. By immunoblotting it has been shown that a subset of PF and FS patients' sera bind to a 160-kD glycoprotein that is identical to DG I, a desmosomal core glycoprotein. Also by immunoblotting, a few PV sera recognize a 33-kD protein from human epidermis and a 140-kD protein from bovine tongue. All PV sera tested by immunoprecipitation bind to a 210-kD glycoprotein that is synthesized by cultured human keratinocytes. This glycoprotein consists of two disulfide-linked polypeptides of 130 and 80 kD. PF sera do not recognize these polypeptides. Thus, even though the antigen specificities at a molecular level of all PF and PV sera are not fully known, it is clear that PV and PF autoantibodies bind different molecules. These findings of disease specific antigens may account for the different clinical forms of these diseases.