Human nevocellular nevus cells are surrounded by basement membrane components. Immunohistologic studies of human nevus cells and melanocytes in vivo and in vitro.
Dermal nevus cells in the skin are surrounded by electron-dense deposits resembling a basement membrane (BM), and epidermal melanocytes rest on the epidermal BM. Using antibodies directed against various BM components, we have determined that the BM-like structure surrounding nevus cells in vivo contains type IV collagen, laminin, and BM-1 proteoglycan, analogous to BM throughout the body, but not bullous pemphigoid antigen or epidermolysis bullosa acquisita antigen that are keratinocyte-associated proteins present in the epidermal BM. Moreover, in vitro, both nevus cells and melanocytes derived from adult donors display intracellular and extracellular fibronectin, BM-1 proteoglycan, type IV collagen, and laminin. In contrast, newborn melanocytes maintained under identical culture conditions display none of these BM components, emphasizing the influence of donor age on cell behavior. The data suggest that dermal nevus cells manufacture a BM in vivo, as do certain other neural crest-derived cells. The apparent shared ability of cultured nevus cells and melanocytes to synthesize BM components, coupled with other previously noted behavioral and morphologic similarities in vitro, suggests that these cell types are very closely related; and that morphologic or histochemical differences present in vivo are the result of environmental influences rather than intrinsic differences.