Comparison among Esc(1–21), Esc(1–21)-1c and LL-37 on the number of viable P. aeruginosa cells (CFU). CFU in mouse lungs (Total = lung homogenate + BAL) and spleens (panel a) as well as on the number of inflammatory cells in the BAL (panel b) of pulmonary-infected mice at 4 hours after peptide administration at 0.1 mg/kg were enumerated. Animals were intra-tracheally infected with 3 million PAO1 cells. The peptides were administered intra-tracheally, at 2 μg (0.1 mg/kg) at 2 hours after bacterial infection. The number of viable Pseudomonas cells in the lung and spleen as well as the number of inflammatory cells in the BAL were evaluated 6 hours after infection, as described in the Experimental section. Results are mean ± SEM from three independent experiments; n = 4–6 mice for each treatment group. Following one-way analysis of variance (ANOVA), posthoc comparisons were made using the Dunnett’s multiple comparison test when the P-value was significant (p < 0.05). *p < 0.05, **p < 0.01, ***p < 0.001 for peptide-treated animals versus PBS-treated mice.