Use of a Monoclonal Antibody (B72.3) as an Immunocytochemical Adjunct to Diagnosis of Adenocarcinoma in Human Effusions1

A monoclonal antibody (MAb), designated B72.3, has been generated using membrane-enriched fractions of a metastatic human breast carcinoma as the immunogen. Previous studies have demonstrated that the reactive antigen, a novel M, 220,000 to 400,000 glycoprotein complex, can be detected in formalinfixed, paraffin-embedded tissue sections of human breast and colon carcinomas, and not in a variety of normal adult human tissues. In this preliminary study, we report that MAb B72.3 may be used as an adjunct for diagnosis of adenocarcinoma in cytological preparations of human effusions. Using the avidinbiotin complex method of immunoperoxidase staining and for malin-fixed, paraffin-embedded cell suspensions, MAb B72.3 detected adenocarcinoma cells in effusions from all of 21 patients with adenocarcinoma of the breast. No reactivity was demon strated in any cell type in benign effusions from 24 patients without cancer, or 13 patients with prior or extant cancer in other body sites; moreover, B72.3 showed no reactivity to leukemic or lymphomatous effusions, or apparent mesothelial cells from malignant effusions. MAb B72.3 also detected adenocarcinoma cells in cytological effusion specimens from 12 of 12 patients with adenocarcinoma of the lung and 16 of 16 patients with adenocarcinoma of the ovary. Thus, these data suggest that the immunocytochemical application of MAb B72.3 should now be considered as an adjunct in the discrimination of adenocarcinoma cells from reactive mesothelial cells in the cytological diagnosis of malignant effusions.