APC-cofactor versus APC-independent anticoagulant activity of protein S. (A) Thrombin generation was initiated with 14 pM tissue factor, 10 μM phospholipid vesicles (20/60/20 DOPS/DOPC/DOPE), and 16 mM CaCl2 (final concentrations) in normal pooled plasma with anti–protein S and anti–protein C antibodies (○), anti–protein C antibodies (•), 40 nM thrombomodulin (▵), 40 nM thrombomodulin, and anti–protein S antibodies (▴). (B,C) Endogenous thrombin potentials (ETP) calculated from time courses of thrombin generation initiated with either 14 pM tissue factor (B) or 1.4 pM tissue factor (C). ETP were determined in plasma without added APC or thrombomodulin (▪), addition of 40 nM thrombomodulin (□) or 7.5 nM APC (▨), and presented in percentage of ETP in plasma with antibodies against protein S and protein C.
