Expression of histo-blood group A type 1, 2 and 3 antigens in normal skin and extramammary Paget's disease.

The distribution of histo-blood group A type 1, 2 and 3 antigens was investigated using immunohistochemistry in normal human skin and extramammary Paget's disease (EMPD). We used monoclonal antibodies (mAbs) Bioclone-A (BA) and AR-1, which react with histo-blood group A type 1/2, and type 3 antigens, respectively. We found that A type 1, 2 and 3 antigens were expressed in the upper layer of the epidermis. We also found that the duct cells of the eccrine glands expressed A type 1/2 antigens and A type 3 antigens regardless of secretor status. The dark cells of the eccrine glands expressed A type 1, 2 and 3 antigens from A blood group secretors, but not from non-secretors. Apocrine glands, hair follicles and sebaceous glands did not express these antigens. Since these antigens were localized in the eccrine glands, we examined the possibility of a skin tumor marker. Interestingly, 7 out of 16 extramammary Paget's disease cases were immunopositive for these antigens. Six cases were accompanied by dermal invasion. Five cases without dermal invasion were immunonegative against these antigens. These results suggest that the expression of histo-blood group A antigens in EMPD are associated with a poor histopathological prognosis.