IMMUNOFLUORESCENT STAINING OF METASTATIC CARCINOMA-CELLS IN SEROUS FLUID WITH CARCINOEMBRYONIC ANTIBODY, EPITHELIAL MEMBRANE ANTIBODY, AUA-1 AND BER-EP4

Using an indirect immunofluorescence technique, we assessed the accuracy and clinical usefulness of a panel of monoclonal and polyclonal antibodies. The panel consisted of carcinoembryonic antibody (CEA) and epithelial membrane antibody (EMA), AUA-1, and Ber-EP4 conjugated with fluorescein isothiocyanate. Twenty-six specimens from pleural, peritoneal or pericardial effusions known to contain carcinoma cells (adenocarcinoma or large cell anaplastic carcinoma) and 16 specimens without carcinoma were first examined. The sensitivity and specificity for each of the antibodies were as follows: CEA, 71% and 75%; EMA, 96% and 81%; AUA-1, 80% and 100%; and Ber-EP4, 85% and 100%, respectively. The panel of antibodies was then applied to a group of 14 'problematic' fluids. These had been identified as causing dilemmas in interpretation, either because the cells in, the fluids were of equivocal appearance on light microscopy, or the cytological diagnosis was different from that expected in the light of the clinical condition of the patient. Insufficient cellular material was present in one specimen. In five (39%) of the cases the immunochemical staining supported the light microscopic diagnosis. In four (30%) cases, however, the results indicated that the original light microscopic report was incorrect. Two of these were examples of large cell carcinoma of the lung, in which false negative reports had been issued on pleural fluids. The other two were cases of benign ovarian tumours in which a false positive report had been issued. The immunostaining also clarified the final diagnosis in the three patients (23%) on whom 'suspicious' cytological reports had previously been issued. The remaining case, fluid from a patient with a high grade mixed Mullerian tumour of the ovary, was unresolved. We conclude that immunofluorescent staining by AUA-1, EMA and Ber-EP4 is an aid in the cytological interpretation of serous fluids. CEA is much less helpful.