UROKINASE-TYPE PLASMINOGEN-ACTIVATOR IN CARCINOMATOUS PLEURAL FLUID

Urokinase-type plasminogen activator (u-PA) is known to be secreted by malignant cells during proliferation and migration, and is associated with tumour cell invasion and metastasis. This study was undertaken t o evaluate whether u-PA is significantly increased in carcinomatous pl eural fluids compared to those due to other aetiologies, and to identi fy the cells in the pleural space that are involved in its accumulatio n, Using an enzyme-linked immunosorbent assay, we quantified u-PA in t he pleural fluid specimens of 40 patients with carcinomatous pleuritis , 18 with tuberculosis, 18 with parapneumonic pleuritis and 11 with co ngestive heart failure (CHF), The level of u-PA was elevated in carcin omatous pleural fluid compared with the level in transudative pleural fluid from patients with CHF (p<0,0001), The levels of u-PA were not s tatistically different between patients with cancer and tuberculosis, or between patients with cancer and pneumonia The levels of u-PA in pa tients who did not respond to chemical pleurodesis were significantly higher than those who had complete response (p=0,0001), In immunocytoc hemical and immunoblotting studies, cancer cells in pleural fluids as well as mesothelial cells contained u-PA, u-PA was detected in the cul ture supernatants of viable pleural cells in the majority of patients with carcinomatous pleuritis, Our results suggest that local release o f urokinase-type plasminogen activator by viable cells, including canc er cells and mesothelial cells, may affect the levels of urokinase-typ e plasminogen activator in pleural fluids.