Platelets are not required for coagulation or endothelial cell activation during Klebsiella pneumosepsis. Very low-PC, low-PC, and control mice were infected with K pneumoniae via the airways and euthanized at 12 or 44 hours. (A) Plasma TATc levels were measured as a marker for systemic coagulation activation. (B) Fibrin(ogen) was detected by western blotting on lung homogenate samples. (C-E) Semiquantification of fibrin(ogen) blots; quantification scores of naive control mice, very low-PC, and low-PC mice were normalized to infected controls. E-selectin was measured in lung homogenates (F) and in plasma (G) as a marker for endothelial cell activation. Data are expressed as box-and-whisker plots depicting the smallest observation, lower quartile, median, upper quartile, and largest observation, or as bars depicting mean ± standard error of the mean (SEM). n = 8 mice per group. *P < .05 and **P < .005, vs control; #P < .05 vs low-PC. Fibr, fibrinogen.