Skin calcium-binding protein immunoreactivity in basal cell carcinoma.

Skin calcium-binding protein (SCaBP) is a low molecular weight protein of unknown function which is localized in the cytoplasm of epidermal basal cells. We have examined SCaBP immunoreactivity in basal cell carcinoma (BCC) since BCC cells retain some of the characteristics of basal cells, including the capacity for proliferation and migration from the dermo-epidermal junction. We also examined immunoreactivity to basement membrane zone (BMZ) antigens (type IV collagen, laminin and bullous pemphigoid antigen) in BCC. We found that all BCC cells showed SCaBP immunoreactivity regardless of the histological type or position of the cells. BMZ antigens were expressed around tumourous buds, although bullous pemphigoid antigen may also present a cytoplasmic immunoreactivity. Our results suggest that SCaBP immunoreactivity is independent of the basal position of the cell, but may be related to the proliferative capacity and the undifferentiated state of the cell.