Effect of δFXII on HK cleavage in mice. (A) FXII-WT, FXII-3C, or δFXII-3C were administered IV to WT C57Bl/6 mice to an estimated final plasma concentration of 140 nM or 40 nM. Shown are nonreducing western blots of plasma collected 0, 15, 30 minutes, or ∼18 hours (overnight [ON]) after FXII infusion. Blots were developed with anti-murine HK IgG (anti-mHKFXI). (B) As in panel A. δFXII-3C was infused into WT, PK-deficient (Klkb1^−/−) mice), or FXI-deficient (F11^−/−) mice (140 nM final plasma concentration). FXII-WT mice also received an IV infusion of vehicle (Control) or monoclonal anti-human FXII IgG 1B2. Samples were analyzed as in panel A. (C-D) WT mice received IV infusions of FXII-WT (C) or FXII-Arg309 (D) (140 nM final plasma concentration). Mice were then infused with vehicle (−TF) or 70 ng/kg human TF (+TF). Samples of plasma collected 0, 15, or 30 minutes postvehicle/TF infusion were analyzed as in panel A. (E) WT mice were treated with vehicle or 70 ng/kg human TF after infusion of FXII-Arg309, as in panel D. Some mice were pretreated with the thrombin inhibitor hirudin (10 mg/kg). FXI-deficient (F11^−/−) mice were treated with 70 ng/kg human TF after FXII-Arg309 infusion. The 2 left panels in E are the same as in panel D. (F) Western blot for plasminogen in plasma from WT C57Bl/6 mice before (C) or after (+ASO) subcutaneous injections of an ASO directed at the mRNA of plasminogen. (G) Western blots of plasma HK in WT mice treated with anti-plasminogen ASO. Mice received FXII-WT (left) or FXII-Arg309 (right) prior to infusion of vehicle (−TF) or 70 ng/kg human TF (+TF). For blots in panels A-E and G, arrows on the right indicate the positions of cleaved HK (HKa), and positions of molecular mass standards in kilodaltons are shown to the left of the images. Plg, the position of the band representing plasminogen.