Reactivity of tumor cells in malignant effusions with a panel of monoclonal and polyclonal antibodies.

A panel of 13 mouse monoclonal antibodies (mAb) and 1 rabbit polyclonal antibody was tested for reactivity with tumor cells in 26 effusions obtained from patients with carcinoma of ovary, breast, or mesothelioma, using an immunoperoxidase staining reaction. Specific staining of tumor cells but not reactive mesothelial cells was demonstrated with some of the mAb in the panel. In 4 of 26 effusions no evidence of malignancy was obtained after routine cytological staining, but this was reversed on the basis of immunoperoxidase staining of tumor cells with the mAb in the panel. Serial effusions were evaluated in 4 patients during the course of chemotherapy, allowing an assessment of effect of therapy on the antigenic characteristics of the tumor cells. In another 4 patients, the results of immunoperoxidase staining of effusions were compared with those obtained by applying the same antibody panel to solid tumor nodules. There was a tendency to develop changes in the pattern of reactivity during therapy, and the pattern of reactivity was more restricted in tumor nodules than in effusions. One of the mAb in our panel (2G3) was consistently shown to produce strong staining of a high proportion of tumor cells in effusions and tumor nodules from patients with ovarian or breast cancer and may be of value in immunocytochemical diagnosis and therapy of epithelial malignancies.