Immunohistochemistry and cytochemistry of experimental rat bladder cancer: binding of the lectins PNA and WGA and of a Le(Y) mouse monoclonal antibody.

Two lectins, peanut agglutinin (PNA) and wheat germ agglutinin (WGA), and a mouse monoclonal antibody against blood group Le(Y) were used to study the distribution of carbohydrate antigens in an experimental rat bladder cancer model. Neoplasia was induced in 28 rats by intravesical installation of N-nitroso-N-methyl-urea (NMU). Fifteen rats were installed with the NMU solvent and served as controls. Urothelial samples were taken from all animals, the atypia were graded and detailed data on the location of the lectin-binding structures and the binding of the monoclonal antibody were obtained by immunohistochemical methods. Urine samples were collected at different times during tumor development and data on the cytological location of the lectin-binding structures and the binding of the monoclonal antibody were obtained by immunocytochemical methods. Examination of the histological distribution of lectin binding structures and Le(Y) antigen showed a characteristic change in carbohydrate antigen expression associated with the development of urothelial atypia. In normal urothelium carbohydrate antigens were present in cytoplasm, whereas they became expressed on cell membranes in non-invasive carcinomas. Immunocytochemistry of urine specimens revealed a lack of correlation between the antigen expression found in exfoliated cells and that found in tissue. Morphologically normal cells from NMU-treated animals were found to express a carcinoma associated antigen pattern.