T and B lymphocytes in pleural effusions.

To determine the diagnostic significance of the determination of T and B lymphocytes in pleural fluid, we studied these cells in peripheral blood and in pleural fluid by means of surface markers. Our study comprised 30 patients suffering from pulmonary tuberculosis, pulmonary malignancy, connective tissue disease, nonspecific pleurisy or congestive cardiac failure. In pulmonary tuberculosis, both the percentage and absolute numbers of T lymphocytes in pleural fluid were significantly higher than in peripheral blood. In patients with pulmonary tuberculosis, pulmonary malignancy or nonspecific pleuritis, the percentages and absolute numbers of B lymphocytes were significantly lower in pleural fluid than in peripheral blood. Considered together with other clinical and laboratory indices, these determinations may aid in the differential diagnosis of pleurisy of various etiology.