LDA-1: a ubiquitous noncollagenous lamina densa component of basement membrane detected by monoclonal antibody technique.

Using monoclonal antibody technology, a new basement membrane antigen, designated as LDA-1, has been identified. This antigen is expressed in all human tissues thus far examined; within skin it is detectable not only within the dermal-epidermal junction but also within dermal vascular and appendageal basement membranes. In addition to human skin, LDA-1 is also detectable within rabbit but not monkey, rat, mouse, guinea pig, or cow skin. This antigen has been ultrastructurally localized to the lamina densa and to a much lesser extent, the adjacent sublamina densa region. ELISA (enzyme-linked immunosorbent assay) revealed no cross-reactivity between LDA-1 and type IV collagen, laminin, fibronectin, and heparan sulfate proteoglycan. In vitro enzymatic studies suggest that LDA-1 is noncollagenous in nature.