T-antigen in normal and neoplastic urothelium.

The expression of the Thomsen-Friedenreich antigen (T-antigen) in normal and neoplastic urothelium was investigated using paraffin-processed and fresh frozen tissue sections obtained by biopsy from 56 patients. The T-antigen was detected through its binding to the peanut agglutinin (PNA) with two methods: a biotin-avidin-peroxidase system or a modified red cell adherence test. In vitro treatment of the tissue sections with neuraminidase induced PNA binding in the normal and neoplastic urothelium as well as the red blood cells and the vascular endothelium. Spontaneous PNA binding was absent in normal bladder epithelium, but was observed in 10% of the noninvasive and 65% of the invasive transitional cell carcinomas (TCC). The positive reactions were seen in the cytoplasm, cell surface, and mucin. These results were correlated with the light and electron microscopic findings and with the detectability of the A, B, H blood group antigens in the same tissues. Ultrastructurally, the PNA binding sites frequently corresponded to the Golgi apparatus and to secretory products which stained with Alcian blue. About 90% of TCCs with spontaneous PNA binding did not express the expected blood group antigen. The latter was also undetectable in 54% of TCCs lacking spontaneous PNA binding. It appears, therefore, that the expression of T-antigen occurs later in the evolution of aggressive TCCs, usually when they have advanced to invasive stages. The finding of spontaneous T-antigen unmasking correlates with the presence of invasion and a higher risk for metastatic involvement of regional lymph nodes.