Use of two epithelium-specific monoclonal antibodies for diagnosis of malignancy in serous effusions.

Two monoclonal antibodies, HMFG2 and AUA1, raised against epithelial-cell determinants were used to detect carcinoma cells in smears of serous effusions. Both antibodies react strongly with malignant epithelial cells but not with normal mesothelial or endothelial cells. A third antibody, 11-4.1, which does not react with any human tissue, was used as a negative control. An immunoperoxidase-staining technique was applied to smears of cells from serous effusions. The immunohistochemical diagnosis was in agreement with the cytological diagnosis. In cases with equivocal cytology in which the diagnosis became clear in later samples, the immunohistochemical diagnosis gave the correct result. With this combination of tumour-associated monoclonal antibodies a confident diagnosis of malignancy in serous effusions can be made.