Expression of the basal cell adhesion molecule (B-CAM) in normal and diseased human skin.

The basal cell adhesion molecule (B-CAM) is a 90-kD cell surface glycoprotein with a characteristic immunoglobulin domain structure. The pattern of B-CAM expression in cultured cells suggests that the molecule is associated with a substrate-adherent growth pattern in some lineages. We investigated the expression of B-CAM in normal and diseased human epidermis by means of immunohistochemistry employing a single batch of high-titer mouse monoclonal antibody G253. Snap-frozen biopsy material from normal skin (n = 8), psoriasis (n = 5), contact dermatitis (n = 6), basal cell carcinoma (n = 5) and fetal skin (n = 6) was studied. In normal human skin, B-CAM was found in varying degrees throughout the epidermis with a preference for suprabasal expression, hair follicles were regularly of a B-CAM-positive phenotype. There were no qualitative differences with regard to the B-CAM expression pattern in normal skin in comparison to psoriasis and contact dermatitis. In contrast, fetal skin (15th to 18th week of gestation) was characterized by B-CAM-positive cells in the basal layer of the epidermis as well as in the outer root sheath of hair follicles. Basal cell carcinomas also regularly expressed high levels of B-CAM. A strong B-CAM-positive phenotype can be found in the outer root sheath of hair follicles of adult and fetal human skin as well as in fetal basal keratinocytes.