Circulating neutrophils are not a major mediator of VT that follows inhibition of antithrombin and protein C. (A) Blood neutrophils levels in mice 3 days after injection with a rat IgG control (–αLy6G; open circles) or a rat monoclonal antibody targeting mouse Ly6G (+αLy6G; filled circles). P < .001, Mann-Whitney rank sum test. (B) Scoring of the clinical phenotype in mice treated with siRNAs targeting Serpinc1 and Proc. Mice exhibiting characteristic clinical signs (blue bars) and mice unaffected (red bars) 3 days after siRNA treatment (end of experiment). One of the mice in both groups (–αLy6G and +αLy6G) died as a result of the thrombotic coagulopathy. P = .317, Fisher’s exact test. (C-D) Ly6G staining of thrombi found in sections of the head. Ly6G staining visualizes neutrophils, which are seen as brown-colored cells in the figures. Representative sections are shown for the –αLy6G (panel C) and +αLy6G groups (panel D). Hematoxylin was used for counterstaining. Black lines represent 100 μm. Supplemental Figure 9 presents enlargement of the images from both panels. (E) Descriptive scoring for the type of detected thrombi. 0: no thrombi found; I + II: thrombi categories were based on structure and layering. Blue bars: –αLy6G (n = 22); red bars: +αLy6G (n = 20). (F) Levels of fibrin deposition in the liver of the control group (–αLy6G) and the neutrophil-depleted group (+αLy6G). P = .931, Mann-Whitney rank sum test. Solid and dashed lines indicate fibrin levels found in solely siNEG-injected C57BL/6J female mice (median and range, respectively, 4.5 ng/mg [3.1, 5.7]).