Use of a monoclonal antibody (B72.3) as a novel immunohistochemical adjunct for the diagnosis of carcinomas in fine needle aspiration biopsy specimens.

Monoclonal antibody B72.3 has been shown to be reactive with a high-molecular-weight glycoprotein complex termed TAG(tumor-associated glycoprotein)-72. By the avidin-biotin immunoperoxidase method, fine needle aspirates and corresponding surgically excised tumor tissues from both malignant and benign tissues were analyzed for TAG-72 expression. Staining (range, 1 to 100 per cent of tumor cells) with monoclonal antibody B72.3 was observed in needle aspirates from 18 of 18 adenocarcinomas and adenosquamous carcinomas of the lung, 17 of 21 adenocarcinomas of the breast, and six of six adenocarcinomas of the colon, as well as adenocarcinomas from other body sites. In contrast, small cell carcinomas of the lung, malignant melanomas, lymphomas, and sarcomas did not stain with the antibody. Benign lesions from the breast, lung, pancreas, parotid, and thyroid also failed to stain. In 66 patients, tumor-bearing tissue had also been resected and was available for comparative examination with monoclonal antibody B72.3. In 62 of these 66 patients, the staining patterns in the aspirates were found to be predictive of the patterns of antibody reactivity in the comparable surgically resected tissues. From these studies it is concluded that monoclonal antibody B72.3 defines a tumor-associated antigen that is expressed in neoplastic cells but not in benign cells and is most selectively expressed in adenocarcinomas. This monoclonal antibody may be used as a novel adjunct for the diagnosis of carcinoma in fine needle aspiration biopsy specimens.