ANALYSIS OF PLEURAL EFFUSIONS USING FLOW-CYTOMETRY

Flow cytometry allows a rapid and accurate analysis of the cells in se rous fluids. The aim of this study was to evaluate the use of flow cyt ometric analysis in malignant pleural effuions. 26 patients (13 female s, 13 males; mean age 52 +/- 19 years; range 16-82) were included in t he study. 15 had malignant pleural effusions (7 adenocarcinoma, 2 lymp homa, 2 chronic myeloid leukemia, 1 ovarian carcinoma, 1 small cell lu ng carcinoma, 1 squamous cell lung carcinoma and empyema, and 1 malign ant mesothelioma) with positive cytology. 2 had benign effusions assoc iated with malignancy (1 squamous cell lung carcinoma and congestive h eart failure, and 1 neuroblastoma and hypoproteinemia). 9 had benign e ffusions (3 tuberculosis, 1 congestive heart failure, 3 para-pneumonic pleural effusion, 1 benign mesothelioma, and 1 pulmonary embolism). F low cytometric analysis of pleural effusions revealed an increased DNA index in malignant effusions: 1.32 +/- 0.44 versus 0.88 +/- 0.23 in b enign effusions (p < 0.04). The cell cycle distribution of cells such as G(1)/G(0) and S in malignant effusions did not differ from that of benign pleural effusions; however G(2)+M increased significantly in ma lignant effusions (p < 0.03). Using analysis of mononuclear immunophen otyping, CD3+, CD4+, and CD8+ cells did not show any significant diffe rence between the two groups. The lymphocyte activation marker CD38 wa s positive in 57.6 +/- 11.5 % of malignant fluid cells and 38.5 +/- 6. 2% of benign fluid cells (p < 0.04). The mean carcinoembryonic antigen levels in malignant and benign pleural effusions were 98.7 +/- 157.3 and 0.9 +/- 1.2 ng/ml, respectively (p < 0.03). In conclusion, the res ults of our study indicate that finding cells with an abnormal DNA con tent strongly supports the diagnosis of malignant pleural effusions. A dditionally, mononuclear cell phenotypes have to be taken into conside ration for malignant pleural effusions, particularly activated T cells . We recommend that flow cytometry should be performed if the cytology is equivocal.