Induction of microparticle- and cell-associated intravascular tissue factor in human endotoxemia

Omer Aras, Arun Shet, Ronald R. Bach, Jessica L. Hysjulien, Arne Slungaard, Robert P. Hebbel, Gines Escolar, Bernd Jilma, Nigel S. Key

Research output: Contribution to journalArticlepeer-review

237 Scopus citations


The precise role of intravascular tissue factor (TF) remains poorly defined, due to the limited availability of assays capable of measuring circulating TF procoagulant activity (PCA). As a model of inflammation-associated intravascular thrombin generation, we studied 18 volunteers receiving an infusion of endotoxin. A novel assay that measures microparticle (MP)-associated TF PCA from a number of cellular sources (but not platelets) demonstrated an 8-fold increase in activity at 3 to 4 hours after endotoxin administration (P < .001), with a return to baseline by 8 hours. TF antigen-positive MPs isolated from plasma were visualized by electron microscopy. Interindividual MP-associated TF response to lipopolysaccharide (LPS) was highly variable. In contrast, a previously described assay that measures total (cell and MP-borne) wholeblood TF PCA demonstrated a more modest increase, with a peak in activity (1.3-fold over baseline; P < .000 01) at 3 to 4 hours, and persistence for more than 24 hours. This surprisingly modest increase in whole-blood TF activity is likely explained by a profound although transient LPS-induced monocytopenia. MP-associated TF PCA was highly correlated with whole-blood TF PCA and total number of circulating MPs, and whole-blood TF PCA was highly correlated with TF mRNA levels.

Original languageEnglish (US)
Pages (from-to)4545-4553
Number of pages9
Issue number12
StatePublished - Jun 15 2004

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