Pathogenic KP does not induce hemorrhagic lung injury, but the cell-free SN of PA is sufficient to induce neutrophil airspace influx and hemorrhagic injury in thrombocytopenic Mpl^−/−mice. (A) Survival of Mpl^−/− and Mpl^+/+ mice following IT inoculation with pathogenic KP by log-rank (Mantel-Cox) test (n = 9 mice/group). In separate experiments, total BAL leukocytes/mL (B), BAL neutrophil counts/mL (C), BAL protein concentrations (mg/mL) (D), lung CFU/mL (E), and gross appearance of BAL fluid (F) (representative tube displayed; n = 9 mice/group) at the 48-hour time point. (G) Gross appearance of BAL fluid from representative Mpl^−/− mice 20 hours after IT administration of either vehicle (LB) or PA cell-free SN with total BAL neutrophils/mL (H) and BAL protein concentrations (mg/mL) (I) (n = 4 mice/group). Each tube or point represents an individual mouse, and the group median is displayed. Statistical comparison by Mann-Whitney U test. *P < .05.