Mice were infected with E. coli plus IgG control or anti IL-11 neutralizing antibody. BALF was collected at the time indicated and analyzed for A) IL-11 protein, B) total protein, and C) LDH activity. N = 4–8. Significance was tested with two-way ANOVA and Sidak’s correction for multiple comparisons. # significant for treatment by ANOVA, * p<0.05. D) Mouse survival. N = 23–25. Survival significance was determined by Log-rank test. ns not significant. Lungs were fixed with PFA, embedded in paraffin, and 5μm sections were stained with H&E. E) representative images of control IgG and anti-IL-11 treated lungs. Bar 25 μm. F) quantification of lung injury. N = 5–6. Significance was tested with a Student’s unpaired t-test. In a separate experiment, mice were treated with IgG or anti-IL-11 in the absence of infection for 24h and G) total BALF protein measured. N = 5–6. Significance tested with a Student’s unpaired t-test.