FIBRINOLYTIC SYSTEM IN PLASMA AND PLEURAL FLUID IN MALIGNANT PLEURAL MESOTHELIOMA

The two major fibrinolytic activators, urokinase-type plasminogen acti vator (u-PA) and tissue-type plasminogen activator (t-PA) may play rol e in tumor spread and metastasis. Malign pleural mesothelioma (MPM) is a kind of tumor with predominantly local invasion and low incidence o f distant metastasis. Tn this study, u-PA, t-PA and PA activator-1 (PA I-1) antigen and activity were measured in plasma and pleural fluid sa mples from patients with MPM, lung cancer and benign effusion. When co mpared to the control group, in MPM group, plasma u-PA and t-PA antige n levels were higher, but plasma u-PA and t-PA activity were comparabl e. PAI-1 antigen was also higher in MPM group. These findings were in contrast to the lung cancer group, in which both activity and immunolo gic measurement of u-PA and t-PA were higher, but PAI-1 antigen was si milar as compared to the control group. It is concluded that excess t- PA and u-PA are balanced in complexes with PAI-1 in MPM, whereas the a mount of PAI-1 in plasma is insufficient to overcome the elevated t-PA and u-PA, in lung cancer. Based on these findings, it may be suggeste d that the balanced fibrinolytic system is responsible for the low inc idence of distant metastasis in MPM. Copyright (C) 1996 Elsevier Scien ce Ltd.