Depletion of pulmonary macrophages contributes to poor outcome.

<p>(<b>A</b>) C57BL/6J mice were treated with clodronate- or PBS-loaded liposomes for 24 hours. Mice were infected intranasally with SA and numbers of macrophages in BAL and lung quantified 24 hours post-infection by flow cytometry (n = 4 for PBS groups, n = 10 for SA groups). (<b>B</b>) Numbers of SA (CFU) recovered from BAL and lung were quantified at 4 and 24 hours post-infection. (<b>C, D</b>) PMNs in BAL and lung 24 hours post-infection. (<b>E</b>) Ratios of CFU to PMNs in BAL and lung. (<b>F</b>) DCs in BAL and lung 24 post-infection. (<b>G</b>) NKs in BAL and lung 4 hours and 24 hours post-infection. (<b>H</b>) Protein in the BAL fluid 24 hours post-infection. (<b>I</b>) Hematoxylin and eosin stain (H&E) staining of mouse lung (magnification 100x; insert, magnification 400x). FACS blots showing depleted macrophages and unchanged PMNs after clodronate treatment are in <b><a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1004820#ppat.1004820.s004" target="_blank">S4D Fig</a>.</b> Data are pooled from three independent experiments. Each point in represents a mouse. Lines show median values. <i>p</i> values obtained by nonparametric Mann-Whitney test.