Sensitivity enhancement of the cytologic detection of cancer cells in effusions by monoclonal antibodies.

Cells from 229 pleural and peritoneal spontaneous fluids and 51 peritoneal lavage fluids from patients with neoplastic and nonneoplastic diseases were studied by indirect immunofluorescence with two monoclonal antibodies; MBr1, prepared against breast carcinoma, and MOv2, prepared against ovarian carcinoma. The results were correlated with those obtained by conventional cytologic methods. A cytologic diagnosis of metastatic carcinoma was established in about 50% of the fluids examined. Sixty percent of the cytologically malignant fluids contained tumor cells reactive with at least one of the two monoclonal antibodies tested. The specificity of the labeling was confirmed by immunoelectron microscopy. In addition, 16 fluids with a negative cytologic diagnosis contained cells strongly immunopositive with MBr1 and/or MOv2. Reactive mesothelial cells were consistently negative. These results suggest that antibodies MBr1 and MOv2 are able to identify cancer cells that do not fully meet conventional morphologic criteria for malignancy. The two reagents, when used in support of cytologic analysis, may substantially reduce the number of false negative cytologic diagnoses of fluids from patients with breast and ovarian carcinomas.