Peanut lectin binding sites in transitional cell carcinoma of the urinary bladder

Peanut lectin (PNA) binds to D Gal B (1-3) D Gal NAc which is the purported antigenic determinant of the so-called T blood group antigen (TAg). We used PNA in an indirect immunofluorescent technique to study TAg in transitional cell carcinomas of the bladder (TCC). All 14 control tissues failed to express TAg, whereas all controls (100%) expressed TAg on the cell membrane after prior treatment with neuraminidase. Sixty-nine percent of Stage O TCC expressed TAg, whereas 100% of cases expressed TAg after treatment with neuraminidase. Staining patterns noted were: granular intracytoplasmic, intracytoplasmic globular, and membrane. There was no correlation between TAg positivity or negativity and subsequent muscle wall invasion in the Stage O TCC group. Fifty percent of Stage B or greater TCC expressed TAg, whereas 27 of 30 (90%) cases expressed TAg after neuraminidase treatment. TAg-staining patterns noted in Stage B tumors were: membrane, granular intracytoplasmic, intracytoplasmic globular, and glycocalyx. Only 47% of Grade III TCC expressed TAg compared with 72% of low-grade TCC. The authors conclude that the expression of TAg reflects the neoplastic transformation of bladder epithelium. The data also suggest that in TCC, TAg positivity is most likely due to incomplete synthesis of MN blood group glycoprotein, as evidenced by loss of a terminal sialic acid, and that there is also evidence of cytostructural "relocalization" of TAg.