A unique epithelial basement membrane antigen defined by a monoclonal antibody (KF-1)

The basement membrane zone (BMZ) of human skin is a complex structure which contains several well-defined components including bullous pemphigoid antigen, laminin, type IV collagen, and proteoglycan. Characterization of additional basement membrane (BM) constituents has been limited by their relative inaccessibility, insolubility, and low tissue concentration. We have produced a murine monoclonal antibody that has enabled us to define a unique constituent of the BMZ of human stratified squamous epithelia. The monoclonal antibody (KF-1) was raised by standard techniques using suction blister-derived trypsinized human epidermal cells as the antigen. Indirect immunofluorescence and immunoperoxidase staining of human and rhesus monkey tissues with KF-1 produced linear BMZ staining of stratified squamous epithelia. Glandular and vascular BMs were not stained. Immunoelectron microscopic studies of normal human skin and esophagus showed specific binding of KF-1 to the lamina densa of the BMZ, a localization identical to that of type IV collagen. However, unlike type IV collagen, which is not species specific and is found in all BMs, the antigen defined by KF-1 is collagenase-resistant and is specific for primate stratified squamous epithelia. These findings confirm the existence of regional variation in BM composition, and demonstrate for the first time that the lamina densa of stratified squamous epithelial BMs contains a constituent other than type IV collagen.