Blood group ABO-related antigens in fetal and normal adult bladder urothelium. Immunohistochemical study of type 2 chain structures with a panel of mouse monoclonal antibodies.

Seven monoclonal antibodies with specificity for blood group antigens carried by type 2 chain core structures (N-acetyllactosamine, H, Le(x), LeY, A monofucosylated, A difucosylated (AleY), A type 3) were used to study the distribution of these antigens in normal human bladder urothelium. The urothelial samples were from 7 fetuses (aged 7 to 21 weeks), and 22 adults. By means of an immunohistochemical method applied to frozen and fixed tissues, localization of antigens in the 3 cell layers of urothelium was compared with individual ABO, Lewis, and Secretor type. During fetal development, N-acetyllactosamine, H, and LeY antigens were continuously expressed, whereas Le(x) varied with age. The A type 3 chain was present in fetal urothelium but A type 2 chain was not. In adults, we observed a unique blood group distribution: with complex antigens like LeY and ALeY in all cell layers, and a unique expression of most of the less complex antigens in the luminal cell layer. Pretreatment of tissue sections with neuraminidase proved that Le(x) and N-acetyllactosamine could be partly substituted by sialic acid A type 3 chain and most of N-acetyllactosamine antigens were present only in cytoplasm, whereas all other examined antigens could be present both in cytoplasm and on cell membranes. Blood group A antigen expression was related to erythrocyte A1 and A2 subtype, and a remarkable correlation was found between type 1 chain related secretor status and expression of Le(x), LeY, and A antigens.