Accumulation of neutrophils in pulmonary vessels. Forty-eight hours after P aeruginosa inoculation, wild-type and G-CSFR^−/− animals were injected with PE-Gr-1 antibody. Five minutes later, neutrophils in blood (A) and lung homogenate (B) were harvested as described in “Materials and methods.” Shown are representative fluorescence-activated cell sorted (FACS) plots of wild-type (left) and G-CSFR^−/− mice (right) stained ex vivo with FITC-7/4 (antineutrophil) antibody. (C) Quantitation of the percentage of 7/4⁺Gr-1⁺ cells in lung homogenate of wild-type (□) and G-CSF^−/− (▪) animals (n = 5). Data represent the mean ± SEM.