The relative importance of vessel wall
tissue factor (TF) in initiating thrombogenesis is not well defined. In contrast, vessel wall
collagens have been well documented as potent inducers of
thrombus formation. We compared the potency of a human TF/
phospholipid surface with that of a surface consisting of human
type III collagen fibrils in triggering
thrombus formation in native human blood at venous and arterial blood flow conditions. A commercial preparation, Thromborel S, was used as a source of human TF. Biochemical characterization of this preparation revealed small amounts of FVII, FIX, and FX
proteins.
Coagulant activity of these
proteins was associated with the FVII
protein only, although it was a very low activity. Studies with anti-TF
antibodies in a one-stage clotting assay showed that the procoagulant activity of Thromborel was mainly a result of TF. The molar ratio of TF to
phospholipid was 1:2 x 10(7).
Thrombus formation in flowing nonanticoagulated human blood drawn directly from an antecubital vein was triggered by either Thromborel S or
collagen fibrils coated on
Thermanox coverslips in a parallel-plate perfusion chamber device. A 1:50 Thromborel S dilution gave maximal
fibrin deposition (90% surface coverage) at a wall shear rate of 100 s-1. However, pretreatment of the TF surface with a monoclonal anti-TF antibody reduced this
fibrin deposition by 93% (P < .001). Thus, TF was essential for the procoagulant activity of the Thromborel S surface in this flow system also. At higher wall shear rates (650 and 2600s-1), less
fibrin was deposited, but the platelet
thrombus formation on the
fibrin mesh increased dramatically.(ABSTRACT TRUNCATED AT 250 WORDS)