At 6 and 12 hours after CLP, lungs were removed from euthanized mice, minced into small pieces, and incubated in RPMI-1640 medium with 1% penicillin-streptomycin and 1% glutamine for 30 minutes at 37°C and at 5% CO 2 in the presence of 1 mg/ml of collagenase type 1 and 50 U/ml of deoxyribonuclease I. After incubation, cells were filtered through a 70-mm cell strainer and washed with RPMI medium. The cells were incubated for 15 minutes at 4°C with CD11b magnetic beads (Miltenyi Biotek, Inc., Auburn, CA) and subsequently applied to MS columns (Miltenyi Biotek, Inc.) for their positive selection. Negatively selected cells were also collected.