Immunocytochemical detection of ovarian carcinoma cells in serous effusions.

Monoclonal antibodies OC 125, OV632, OV-TL 3, MOv18 and OV-TL 23, directed against distinct ovarian carcinoma-associated antigens, were examined for their value in cytopathologic diagnosis. Their sensitivity and specificity in staining ovarian carcinoma cells in serous effusions we determined using the indirect immunoperoxidase technique. Smears prepared from 140 serous effusions (73 benign, 67 malignant) were immunostained with the five antibodies. OC 125 and MOv18 reacted positively with 96% and 81% of the smears of effusions from ovarian carcinoma patients, respectively, while OV-TL 3, OV632 and OV-TL 23 stained a lower percentage of the samples (73%, 65% and 62%, respectively). In discriminating ovarian carcinoma cells from benign (mesothelial or inflammatory) cells in serous effusions, MOv18 demonstrated the highest specificity (100%) since none of the 73 samples from benign effusions were stained upon incubation with this antibody. OC 125 cannot be used for this purpose due to its reactivity with mesothelial cells in benign samples. Staining cytologic preparations of malignant effusions from cancer patients with carcinomas not originating in the ovary revealed that OV632 and OV-TL 23 may be useful adjuncts to determine the origin of the carcinoma cells found in serous effusions. The reactivity of these antibodies was highly selective for ovarian carcinoma cells, staining only 6% and 0% of the samples from the non-ovarian carcinoma samples, respectively. It is concluded that MOv18 is the most suitable antibody for distinguishing ovarian carcinoma cells from mesothelial cells in serous effusions, while OV632 and OV-TL 23 especially may help to assess whether carcinoma cells found in effusions originate in the ovary.