Surface-initiated clotting and thrombin generation in human plasma. (A) Clotting times in an aPTT assay for pooled normal plasma (PNP), FXII-deficient plasma (FXII DP), or FXII-deficient plasma supplemented with recombinant FXII species (FXII added to FXII DP). Each symbol indicates 1 clotting time and the horizontal bars indicate means for each group ± 1 SD. (B) Thrombin generation in FXII-deficient plasma supplemented with PTT-A reagent in the absence of FXII (No XII dotted line) or in the presence of plasma FXII (dashed line) or FXII-WT (solid line). (C) Thrombin generation in FXII-deficient plasma supplemented with PTT-A reagent and FXII-WT (solid line), FXII-T (dashed line), or FXII-S544A (dotted line). (D) Reactions for FXII-WT and FXII-T shown in panel C run in the presence of CTI or anti-FXI IgG 01A6. For all panels, results represent means for 3 runs.