ABSTRACT
Releasable tissue plasminogen activator (t-PA) and the fast inhibitor of t-PA were measured in 18 controls and a pedigree with venous thrombosis. The functional assay was performed by a technique that destroys the t-PA inhibitor when blood is drawn. It was found that activator and inhibitor levels varied widely in the control group. One patient demonstrated inhibitor levels, on two different occasions, of 2.82 and 3.54 IU of t-PA per milliliter of plasma, as compared with a releasable activator level of 1.87 IU/mL. The t-PA antigen levels of this patient and the remainder of the pedigree were essentially normal for all seven subjects. Thus, it is suggested that the previously reported fibrinolytic disorder in this pedigree represents an imbalance between activator and inhibitor levels rather than an actual deficiency of t-PA.
Subject(s)
Fibrinolysis , Tissue Plasminogen Activator/blood , Antigens/analysis , Blood Proteins/metabolism , Glycoproteins/metabolism , Humans , Mesenteric Veins , Pedigree , Protein C , Protein S , Pulmonary Embolism/blood , Pulmonary Embolism/genetics , Thrombosis/blood , Thrombosis/genetics , Tissue Plasminogen Activator/antagonists & inhibitors , Tissue Plasminogen Activator/immunologyABSTRACT
Releasable vascular plasminogen activator was measured in 28 patients (14 males and 14 females) with a history of thrombotic strokes documented by computed tomographic scanning. Levels were compared with those in a control population of 126 healthy subjects with no history of thromboembolic disease. The patient population tended to have higher levels of activator than the control population, 0.53 Committee on Thrombolytic Agents (CTA) units/ml of plasma for patients versus 0.21 CTA units/ml for control subjects; however, there was a wide distribution of values, as reported in all previous populations. Since plasminogen activator levels distribute in a non-Gaussian manner, patient values and control values were stratified into deciles. By this approach, the distribution among the patient was not significantly different from that among the control subjects except in females, who demonstrated skewing to higher deciles (p = 0.019). It is concluded that thrombotic strokes are not associated with low levels of releasable vascular plasminogen activator, and in fact, these patients may present with levels considerably above the mean for normal subjects.
