Tissue factor expression in Klkb1^−/− mice. (A) Aortic tissue factor (mTF) mRNA determined in Klkb1^+/+ (n = 19), Klkb1^−/− (n = 9), and Klkb1^−/− + nimesulide (Nimes) (n = 5). (B) Measurement of TF activity in aortic lysates of Klkb1^+/+ and Klkb1^−/− mice by chromogenic assay (n = 6 aortas per group). (C) Representative immunofluorescence of carotid artery TF antigen. The images were taken with a Nikon Eclipse TE2000-S microscope at 10× magnification. (D) The relative TF antigen presence in carotid arteries in Klkb1^+/+ and Klkb1^−/− tissue (n = 4 arteries per genotype). (E) Low-dose (0.5 pM) exogenous tissue factor–induced thrombin generation times (TGT) in Klkb1^+/+ and Klkb1^−/− plasmas (n = 3 per group). (F) Peak height and AUC were calculated and quantified from the TGT curves in (E). (G) TGT in Klkb1^+/+and Klkb1^−/− plasma without added TF in the absence or presence of 2 nM rHA-Infestin-4 (n = 6 per group). (H-I) Peak height and AUC, respectively, were calculated and quantified from the TGT curves in (G). In (E) and (G), the slopes of the TGT are actual values in arbitrary units. In the absence or presence of rHA-Infestin-4 (2 nM), Klkb1^−/− plasma had reduced endogenous thrombin generation when compared with Klkb1^+/+ plasma. Data are presented as mean ± SEM for all experiments. *Significant difference (P < .05) between the 2 groups on Student t test or 1-way ANOVA test when more than 2 groups of data are compared.