IMMUNOREACTIVITY OF CANINE TRANSITIONAL-CELL CARCINOMA OF THE URINARY-BLADDER WITH MONOCLONAL-ANTIBODIES TO TUMOR-ASSOCIATED GLYCOPROTEIN-72

Tumor-associated glycoprotein 72 (TAG-72) is a large, high molecular w eight, mucinlike antigen that is expressed in a wide variety of human carcinomas. Three different TAG-72 monoclonal antibodies (MAbs), desig nated B72.3, CC49, and CC83, were applied to the following archived sa mples from the dog: 1) 51 transitional cell carcinomas of the urinary bladder, 2) 15 hyperplastic/inflamed urinary bladders, and 3) eight no rmal urinary bladders. Immunoreactivity was detected with an avidin-bi otin complex immunoperoxidase method. Fifty-three percent (27/51) of t ransitional cell carcinomas were positive (greater than or equal to 5% staining) for MAb B72.3. MAb B72.3 staining of these transitional cel l carcinomas did not statistically correlate with any of the examined features of malignancy, including histologic grade, clinical stage, DN A ploidy, or presence of vascular/lymphatic invasion. In regard to the staining of transitional cell carcinoma by the other two TAG-72 antib odies, 53% (27/51) of the samples were positive for MAb CC83 and 63% ( 32/51) were positive for MAb CC49. The finding that similar population s of neoplastic urothelial cells in serial sections from the same neop lasm stained with all three TAG-72 antibodies supports the hypothesis that an antigen similar to TAG-72 was expressed in canine transitional cell carcinoma. None of the normal urinary bladders nor any of the hy perplastic/inflamed urinary bladders stained with any of the three TAG -72 antibodies tested. The results of these studies demonstrated that the staining of canine transitional cell carcinoma with all three TAG- 72 antibodies was specific for neoplastic urothelial cells and that an antigen similar to TAG-72 was expressed.