Increased plasmin generation and activity in hiv-infected patients: In vivo rather than in vitro activation of the fibrinolytic system

Abstract Since changes in the fibrinolytic system have been previously reported in patients infected by the immunodeficiency virus (HIV), the present study was undertaken to evaluate plasminogen activation as well as plasmin activity in HIV-infected patients. For that purpose, we studied two groups of 20 HIV-infected patients each, classified upon the absolute number of CD4+ lymphocytes: patients with CD4+ below 200 × 10 6 /L (n = 20) were classified as having AIDS, according to the classification of the Centers for Disease Control (CDC, Atlanta). The control group consisted of 20 age- and sex-matched healthy HIV-negative individuals. Plasmin-plasmin inhibitor complexes (PPI complexes), fibrin and fibrinogen degradation products (FbDP, FgDP) were evaluated using commercially available ELISA. All blood samples were collected into evacuated tubes containing 0.129 M tri-Na citrate. In addition, PPI complex were assayed in specimen collected in two other anticoagulant mixtures. The plasma levels of PPI complex, FbDP, and FgDP were found significantly higher in both groups of HIV-infected patients than in controls. However, despite a trend to higher levels, the plasma levels of markers were not significantly different in AIDS and non AIDS patients. The composition of the anticoagulant mixture did not significantly influence the plasma levels of PPI complex. So, the citrated evacuated tubes were found to be convenient for the measurement of PPI complexes in clinical materials. These results suggest that plasmin is overgenerated in HIV-infected patients and only neutralized in part by α 2 - antiplasmin. The presence of unopposed plasmin was suggested by the significant increased levels of fibrin and fibrinogen degradation products. In conclusion, the highly significant correlation demonstrated between PPI complex and FbDP support the hypothesis of an activation of both the fibrinolytic and the coagulation systems in HIV-infected patients.