The specific activity of plasminogen activator inhibitor-1 in disseminated intravascular coagulation with acute promyelocytic leukemia

Abstract

In disseminated intravascular coagulation (DIC) with acute promyelocytic leukemia (APL) in the absence of severe infection, marked fibrinolysis was noted in comparison with normal levels of antithrombin III, which is a major inhibitor of the coagulation system. Increased plasminogen activator inhibitor-1 (PAI-1) antigen levels in plasma from patients with septicemia decreased the ratio of the plasma clot lysis rate induced by an anti-alpha 2-plasmin inhibitor monoclonal antibody to the tissue-type plasminogen activator (t-PA) concentration. This decrease was not as prominent in plasma from patients with DIC, especially those with APL. To explore the character of PAI-1 in these plasmas, we measured the specific activity of PAI-1 by determining the ratio of active PAI-1 antigen to t-PA-unbound PAI-1 antigen. To calculate the amount of active PAI-1 antigen, the amount of t-PA/PAI-1 complex before and after the addition of a fixed amount of t-PA to the sample was measured by a sandwich solid-phase enzyme-linked immunosorbent assay using anti-PAI-1 and anti-t-PA monoclonal antibodies. The assay to measure total PAI-1 antigen used three monoclonal anti-PAI-1 antibodies and had similar sensitivities to free active, latent, vitronectin-bound and t-PA-bound PAI-1. The specific activity of PAI-1 decreased in patients with DIC (43.7% +/- 30.6%) and in DIC cases with APL (10.3% +/- 6.0%) in comparison to patients with septicemia (83.7% +/- 20.2%) or normal controls (85.8% +/- 27.3%). In DIC associated with APL, degraded forms of PAI-1 were detected in plasma by immunoblotting. These results suggest that a decrease in the specific activity of PAI-1 and an increase in secondary fibrinolysis result in a hyperfibrinolytic state in DIC patients with APL.