A new marker for human cancer cells. 3. Immunocytochemical detection of malignant cells in serous fluids with the Ca1 antibody.

The Ca1 antibody has been used in an immunocytochemical procedure on smears of cells recovered from 50 effusions from the pericardial, peritoneal, and pleural cavities. In 25 samples containing malignant cells, as assessed by conventional morphological criteria, this antibody distinguished malignant from non-malignant cells in 21 samples. The exceptions were 2 lymphomas and 2 out of 6 carcinomas of the lung. The Ca1 antibody also reacted with malignant mesothelial cells from 2 mesotheliomas, but not with reactive mesothelial cells. This antibody thus provides a new method for the identification of malignant cells in pericardial, peritoneal, and pleural effusions.