Effect of prothrombin supplementation on fibrinolysis and TAFI activation. Normal pooled plasma (NP, □) and TAFI-depleted plasma (▦) were supplemented with purified human prothrombin to obtain the indicated plasma concentration of total prothrombin. Fibrinolysis was studied by a turbidimetric assay using a tissue factor–induced plasma clot exposed to 25 ng/mL exogenous t-PA. NP was also tested in the presence of CPI (50 μg/mL, ▪). The numbers on NP bars indicate the amount of TAFIa, expressed as percentage of total TAFI, recorded at 30 minutes from the start of the experiment. Data are the mean ± SD of 3 experiments.