Competitive migration of PSGL-1^−/− and DKO neutrophils into the inflamed peritoneum. Peripheral blood leukocytes were isolated from PSGL-1^−/− and DKO mice and labeled with CFSE and TRITC, respectively. The mixture of these cells was injected via the tail vein into recipient DKO mice that had just received thioglycolate intraperitoneally. After 4 and 8 hours, the blood and peritoneal exudate cells were collected, stained with anti–Gr-1-APC, and analyzed by flow cytometry. (A) Representative plots showing CFSE-labeled PSGL-1^−/− neutrophils and TRITC-labeled DKO neutrophils in the input, and the peritoneal exudates and peripheral blood collected 4 hours after injection. (B) The ratio of DKO neutrophils to PSGL-1^−/− neutrophils in the peritoneal exudates and peripheral blood normalized by the input ratio. Data are expressed as means plus or minus SEM from 3 mice. Results represent one of 3 similar experiments. *P < .05; ***P < .001.