Abstract
Homozygous or doubly heterozygous protein-C deficiency can present at birth with purpura fulminans or later in life with venous thrombosis. Two homozygous patients who had previously sustained thrombotic episodes were investigated at a time when they were asymptomatic and not receiving antithrombotic therapy. The plasma levels of protein-C antigen and activity in both individuals were approximately 20% of normal. We administered a highly purified plasma-derived protein C concentrate to these individuals and monitored levels of several markers of in vivo coagulation activation. Assays for protein-C activation (activated protein C and protein C activation peptide) showed a sustained increase from reduced baseline levels, whereas thrombin generation (as measured by prothrombin fragment F1+2) gradually decreased over about 24 hours into the normal range. These investigations provide direct evidence that protein C is converted to activated protein C in vivo, and that the protein-C anticoagulant pathway is a tonically active mechanism in the regulation of hemostatic system activation in humans.
Original language | English (US) |
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Pages (from-to) | 1159-1164 |
Number of pages | 6 |
Journal | Blood |
Volume | 82 |
Issue number | 4 |
State | Published - Aug 15 1993 |
Externally published | Yes |
ASJC Scopus subject areas
- Biochemistry
- Immunology
- Hematology
- Cell Biology