Characterization of Pemphigus Foliaceus Antigen from Human Epidermis

Abstract

Pemphigus foliaceus (PF) and its endemic form, Fogo Selvagem (FS), are characterized by subcorneal vesicles and pathogenic IgG autoantibodies directed against keratinocyte surface antigens. A major pool of FS antigen(s) remains bound to the insoluble epidermal envelope fraction. In this paper we demonstrate that this antigen(s) can be released from the envelope fraction by sonication. By immune precipitation four components can be detected, having molecular weights (MW) of 260, 80, 62, and 45 kD. The 260-kD component is lost by boiling or extraction with glycine HCl at pH 2.8. The major components appear to be the 80- and 62-kD poly-peptides. They chromatograph as a unit by gel filtration in 0.1% SDS, in the MW range of 115-120 kD. The FS antigen(s) appears to be cationic, forming insoluble complexes at low pH with SDS, and is labile to ammonium sulfate and freezing and thawing. It is unaffected by positive pressure concentration, 50% acetone precipitation, and reduction/alkylation. The FS antigen(s) is precipitated by all FS and nonendemic PF sera except those in complete clinical and serologic remission. The FS antigen(s) is also precipitated by 50% of pemphigus vulgaris but none of the bullous pemphigoid sera tested. All FS antigenic components are immunoprecipitated by IgG4 autoantibodies, but the IgG1 subclass from the same patients appear to immunoprecipitate only the 62-kD polypeptide. The FS antigen(s) is able to adsorb human autoantibodies against human desmoglein 1 (DG1), but not rabbit antisera against bovine DG1 or 2. This paper shows that physical stress, i.e., sonication, may be able to solubilize sufficient FS antigen(s) from the epidermal envelope fractions for further chemical characterization. The relationship of these FS antigen(s) to other reported FS antigens is presently unknown.