Wildtype (white bar) and Mmp28−/− mice (black bar) mice were exposed to aerosolized P. aeruginosa and harvested at 4 and 24 h for BALF cell counts and differential. (A) Total cell counts, demonstrating significantly reduced cell counts at 24 h in Mmp28−/− mice. (B) Total neutrophils (PMNs), demonstrating reduced neutrophil recruitment at 24 h in the Mmp28−/− mice, and (C) Total macrophages (MACs), demonstrating increased early macrophage recruitment at 4 h in Mmp28−/− mice. (*p<0.05) (D) Representative cytospins of BALF collected 4 h after P. aeruginosa infection in.wildtype and Mmp28−/− mice. Macrophages (arrow heads). Data are mean ± SEM, results represent 10 mice/timepoint.