Effect of limiting (0.2 pM) and excess (4 pM) TF on plasma thrombin generation in factor IX–deficient plasma. Thrombin generation was initiated with 0.2 pM (A) or 4 pM (B) human TF, 8.3 μM PC:PS vesicles, and 40 μg/mL CTI (plasma concentrations) in factor IX–deficient plasma with or without addition of 100% (90 nM) of plasma factor IX (pFIX): no TF or pFIX control (●), 90 nM pFIX control (○), 0.2 pM TF (■), 0.2 pM TF and 90 nM pFIX (□), 4 pM TF (▴), 4 pM TF and 90 nM pFIX (▵). The time course of thrombin generation was measured as described in “Fluorogenic assay for detection of plasma thrombin generation.” Thrombin generation curves represent the mean thrombin concentration over the first 30 minutes from replicate determinations (n = 3) and are identified by representative points.