Tissue Plasminogen Activator (t-PA) and Plasminogen Activator Inhibitor-1 (PAI-1) in Essential Thrombocythemia and Polycythemia Vera and Thrombotic Complications.

Thrombotic complications are frequent in patients with essential thrombocythemia (ET) and polycythemia vera (PV). While a thrombin- and tissue plasminogen activator (t-PA)-regulated release of t-PA and plasminogen activator inhibitor-1 (PAI-1), respectively, has been shown and an association between elevated t-PA and PAI-1 and thrombogenesis has been studied for several vascular diseases, few studies have concentrated on the correlation between t-PA and PAI-1 levels and thrombogenesis in these myeloproliferative disorders. Therefore, we investigated prothrombin fragment 1+2 (F1+2), as marker of thrombin generation, and t-PA and PAI-1 in patients with ET and PV and thrombosis. We included 44 patients, 22 ET (5 men and 17 women, mean age 55 years) and 22 PV (17 men and 5 women, mean age 60 years) who fulfilled PVSG. The mean duration of disease was 4.5 years. Most received cytoreduction, such as hydroxyurea (13 ET and 14 PV), interferon-alpha (2 ET), anagrelide hydrochloride (5 ET) or phlebotomy (8 PV). None of studied patients had thrombotic risk factors. Of 44 patients, 25 (12 ET and 13 PV) developed thrombosis, whereas 19 (10 ET and 9 PV) did not. Measurements were assayed by ELISA. All patients had increased F1+2 (2.8±2.8 nmol/L vs 0.7±0.2 nmol/L) (p=0.001). t-PA and PAI-1 were higher in those patients with previous thrombosis than in asymptomatic patients (130±62 ng/ml vs 89±69 ng/ml and 45±20 ng/ml vs 57±27 ng/ml, respectively) (p=0.043 and p=0.085, respectively). A positive correlation there was between F1+2 and t-PA and t-PA and PAI-1 (p<0.0001 and p<0.0001, respectively). These findings suggest that a disfibrinolysis may be in ET and PV and that t-PA and PAI-1 may be predictive additional factors of the thrombotic tendency of these patients.