Immunopathologic analysis of human urinary bladder cancer. Characterization of two new antigens associated with low-grade superficial bladder tumors.

The authors have further characterized the normal human tissue distribution and tumor expression of two highly restricted tumor-associated antigens, detected by mouse monoclonal antibodies M344 and 19A211, which are primarily expressed on low-grade superficial urinary bladder tumors. This study was conducted using immunohistochemical staining of frozen and deparaffinized sections of human normal and tumor tissues. The antigens are stable and well preserved on deparaffinized tissue sections. M344 antibody identifies a high-molecular-weight determinant on a cytosolic protein component of over 300,000 Mr. This antigen was not detected on any normal tissue analyzed, including 14 specimens of normal urothelium and 22 cases of cystitis; however, M344 was positive in 74.5% of Ta-T1 tumors and 11% of T3-T4 tumors. 19A211 antibody identifies a sialylated epitope on a cytoplasmic protein complex of 100,000 to 200,000 Mr. This antigen also was expressed preferentially on low-grade superficial bladder tumors (77% Ta-T1) and less frequently on deeply infiltrating tumors (10% T3-4). 19A211 was negative on all normal cells tested, with the exception of umbrella cells, in approximately 25% of the normal urothelium and cystitis specimens studied. Either one or both of these tumor-associated antigens are detected in approximately 80% of low-grade papillary superficial tumors and carcinoma in situ of the urinary bladder. The expression of these antigens on a subset of low-grade bladder tumors, known to progress in only about 10% of cases, suggests that phenotypic differences may reflect biologic potential. Beyond their possible biologic significance, antibodies M344 and 19A211 may provide clinically useful probes for early detection and stratification of urinary bladder tumors.