Immunohistochemical application of monoclonal antibodies to reveal the structure and localization of carbohydrate antigens. N-acetyllactosamine-related carbohydrate antigens in human biliary epithelial cells.

With the use of a panel of monoclonal antibodies against structurally related carbohydrate antigens, finely regulated cellular phenotype of the carbohydrate antigens can be characterized. As a model system, the expression of N-acetyllactosamine-related antigens in human biliary epithelial cells was investigated using 16 murine monoclonal antibodies against different carbohydrate epitopes. Human biliary epithelial cells expressed type 1 backbone-related antigens at all synthetic stages. Type 2 backbone and its monofucosylated structures, i.e., Lex and H, were never detected. More complex type 2 chain antigens, i.e., Ley, A and ALey, were apparently expressed. Types 3 and 4 chain antigens were also shown to be expressed. However, the expression of N-acetyllactosamine-related antigen was polymorphic and differed from one individual to another. Furthermore, in spite of the topographical continuity of the biliary tree, biliary epithelial cells were not always equal in the expression of N-acetyllactosamine-related antigens. As a conclusion, not only the localization but also the structure of carbohydrate antigens can be immunohistochemically studied on the tissue sections with the use of well defined monoclonal antibodies.