IMMUNOREACTIVITY OF CANINE EPITHELIAL AND NONEPITHELIAL NEOPLASMS WITH MONOCLONAL-ANTIBODY B72.3

Monoclonal antibody (MAb)B72.3, which binds to a human tumor-associated glycoprotein termed TAG-72, was applied to a wide range of epithelial and nonepithelial neoplasms from dogs. Immunoreactivity was detected by the use of an avidin-biotin complex (ABC) immunoperoxidase method. A variety of epithelial neoplasms, but none of the nonepithelial neoplasms, were positive (greater than or equal to 5% staining) for MAb B72.3. MAb B72.3 stained 100% (4/4) of gastric, 100% (6/6) of intestinal, 50% (2/4) of pancreatic, and 80% (4/5) of rectal adenocarcinomas but only 20% (1/5) of squamous cell carcinomas and 20% (1/5) of complex tubular mammary gland adenocarcinomas. None of the hepatocellular carcinomas and perianal and sebaceous gland adenocarcinomas stained. Most types of benign epithelial neoplasms did not stain, except for 75% (6/8) of rectal adenomas and 25% (1/4) of squamous cell papillomas. Normal gastrointestinal mucosa adjacent to and entrapped in neoplasms did stain with MAb B72.3. None of the benign and malignant nonepithelial neoplasms of mesenchymal, neuroendocrine, or lymphohematopoietic tissue origin stained. The results of this study demonstrate that MAb B72.3 has selective immunoreactivity for adenocarcinomas, especially those arising from the digestive tract; however, limited immunoreactivity was observed for other types of carcinomas and benign epithelial neoplasms and for normal gastrointestinal mucosa in the dog.