Blackwell Publishing Journal Backfiles 1879-2005
The very late antigens, or VLA proteins, are a family of cell surface heterodimers (α1–6β1) that mediate cell adhesion to specific components of the extracellular matrix (collagens, fibronectin, laminin). In normal human epidermis, the common VLA β1 subunit is expressed on basal keratinocytes (BK). Langerhans cells (LC) and melanocytes. By means of light and electron microscopic immunostaining procedures, we have investigated the distribution of VLA α1,2,3,4,6 subunits on normal human adult and foetal epidermal cells, α1 antigen expression was not observed on any epidermal cell type. Both during foetal development and in adult epidermis, α2 and α3 were strongly expressed on the cell membrane of BK, while α6 was mainly expressed at their dermal pole. These different patterns of distribution suggest that the α6 subunit may mediate BK anchorage to the basement membrane zone, while the α2 and α3 subunits may also be involved in intercellular adhesion. Moreover, with immunoelectron microscopy, LC were seen to be weakly α4 and α6 positive and melanocytes were α3 and α6 positive. Thus, VLA proteins are expressed by epidermal cells in a cell-type-specific pattern that could be related to particular functional roles of these proteins.
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