Cell Surface Antigens of Human Bladder Tumors: Definition of Tumor Subsets by Monoclonal Antibodies and Correlation with Growth Characteristics1

Normal human urothelium and tumors of urothelial origin were ana lyzed with a panel of seven mouse monoclonal antibodies that identify surface antigens of cultured bladder cancer cell lines. Three categories of antigens were defined on the basis of differential expression on normal urothelium versus bladder tumors. Om5 (a category 1 antigen) is a highly restricted, differentiation antigen detected in the normal urothelium of 50-60% individuals. No other normal cell type in Om5~ or OmS* individuals expresses OmS. The incidence of OmS expression in super ficial bladder tumors is significantly higher (88%) than in normal urothe lium, whereas its expression in invasive or metastatic tumors is far lower (20%), suggesting OmS gain/loss in bladder tumors. Paired biopsies of normal urothelium and bladder tumors from the same individuals have shown OmS induction in the superficial bladder tumors of OmS" individ uals and OmS loss in invasive bladder cancers of OmS* individuals. Category 2 antigens (T43, T138, T23) are not expressed by normal urothelium or most superficial bladder tumors but are detected on a high proportion of invasive or metastatic bladder tumors, indicating that category 2 antigens are associated with late stages of tumor progression. Category 3 antigens (T16, 1X7,J143) provide lineage markers for normal or neoplastic cells of urothelial origin, being found on normal urothelium and virtually all bladder tumors. Thus, differential expression of category 1 and 2 antigens divide bladder tumors into distinct subsets, and these subsets correlate with pathological and clinical features of the disease.