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

Monoclonal antibody (MAb)B72.3, which binds to a human tumor-associate d glycoprotein termed TAG-72, was applied to a wide range of epithelia l 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 neop lasms, were positive (greater than or equal to 5% staining) for MAb B7 2.3. 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 t ubular mammary gland adenocarcinomas. None of the hepatocellular carci nomas and perianal and sebaceous gland adenocarcinomas stained. Most t ypes 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 st ain with MAb B72.3. None of the benign and malignant nonepithelial neo plasms of mesenchymal, neuroendocrine, or lymphohematopoietic tissue o rigin stained. The results of this study demonstrate that MAb B72.3 ha s selective immunoreactivity for adenocarcinomas, especially those ari sing from the digestive tract; however, limited immunoreactivity was o bserved for other types of carcinomas and benign epithelial neoplasms and for normal gastrointestinal mucosa in the dog.