WASp is necessary for neutrophil emigration into lungs. (A) Experimental design of recruitment of adoptively transferred neutrophils in the lung. WT and WASp^−/− neutrophils were labeled either with CSFE (in green) or with SNARF1 (in red). Labeled cells were mixed (1:1; eg, WT-CFSE:WASp^−/−-SNARF1 or WT-SNARF1:WASp^−/−-CFSE) and transferred to WT recipients at the time of LPS lung challenged. The amount of labeled neutrophils recovered in BALF 4 hours after challenge was evaluated by flow cytometry. (B) Representative flow cytometry charts of labeled neutrophils in the mixed population (left panel), in the blood (middle panel), in the BALF (right panel). (C) Relative recruitment of neutrophils calculated as ratio of WASP relative to WT (mean ± SD; n = 5, each experiment; **P < .01). See supplemental Methods for detail of methodology.