T-antigen and Tn-antigen in urinary bladder cancer(Clinical Application of Tumor Antigen)

Recently, several investigators have demonstrated that Thomsen-Friedenreich antigen (T-Ag) and Tn-antigen (Tn-Ag) are expressed on the cells of several cancers including urinary bladder cancer. Antibodies against T-Ag are detectable in healthy as well as patient sera. T-Ag is composed of a specific carbohydrate chain, galactose-β- -1-3-N-acetylgalactosamine (GalNAc), which is specifically detectable through the immunohistochemical binding of peanut agglutinin (PNA). In normal cells, T-Ag is cryptic (cT-Ag) and can be unmasked by treatment with neuraminidase. Tn-Ag is composed of another carbohydrate chain, α-GalNAc-serine/threonine, and binds specifically to Vicia villosa agglutinin (VVA) or B_4 lectin from VVA. With the use of these lectins, the presence or absence of T-Ag and Tn-Ag was examined in normal bladder epithelium and specimens from 53cases of human urinary bladder transitional cell carcinoma of various histological grades by means of the avidin-biotin-immunoperoxidase technique. The correlation between the expression of these antigens and the patient's clinical course was estimated. Out of 21 patients in whom the tumors expressed the phenotype Tn-Ag(+), T-Ag(+), or cT-Ag(-), 17 suffered from invasive recurrence. Although patients with tumors expressing the phenotypes T-Ag(-) and cT-Ag(+) have been reported to show a good clinical course, in our studies some of them showed a switch to invasive recurrence. Of 38 cases expressing the phenotypes T-Ag(-) and cT-Ag(+), 6 had tumors that carried Tn-Ag. Five of them suffered form invasive recurrence. These results indicated that the detection of Tn-Ag in combination with the examination of T-Ag and cT-Ag is useful for estimating the degree of malignancy of bladder cancer and the patient's clinical course. Besides, we evaluated serum anti-T antibody titer in bladder cancer patients by enzyme linked immunosorbent assay. Bladder cancer patients had depressed levels of IgM anti-T antibodies. On the contrary, levels of IgG anti-T antibody in bladder cancer patients were significantly increased (p