Characterization of 230-kD bullous pemphigoid antigen associated with the detergent insoluble fraction of cultured keratinocytes

Abstract

The 230-kD protein identified by antibodies from patients with bullous pemphigoid (BP) has a dual location in cultured normal human epidermal keratinocytes: part in a high-speed supernatant of homogenized cells and part in a particulate fraction, where it is resistant to extraction by non-ionic detergent or mild base. Antibodies were affinity purified from the particulate 230-kD BP antigen, which can be extracted in the presence of urea. The affinity-purified antibodies bind not only the cytosolic 230-kD protein, showing that it is related, if not identical, to the particulate form, but also produce a discontinuous granular pattern by indirect immunofluorescence in the basement membrane zone of rabbit esophagus. In stratifying epidermal cultures, expression of the 230kD BP antigen is limited to basal cells. These data are consistent with 230-kD BP antigen involvement in keratinocyte basal cell interaction with extracellular matrix and indicate that the cultured cell may provide a useful model for analysis of 230-kD BP antigen function. © 1991.