Neutrophils require chemokine but not selectin signaling to migrate into the peritoneum after thioglycollate challenge. (A) WT or Cxcr2^−/− mice were injected intraperitoneally with thioglycollate. After 2 hours, peritoneal cells were collected and the number of neutrophils was measured by flow cytometry. Neutrophils were identified by their scatter properties and by staining with anti-Ly6G mAb. (B-G) WT mice were injected intraperitoneally with thioglycollate. After 2 hours, they were injected intravenously with a 1:1 mixture of PKH-67-labeled WT bone marrow leukocytes and PKH-26-labeled bone marrow leukocytes of the indicated genotype. After another 2 hours, blood and peritoneal cells were collected, and the number of neutrophils labeled with each dye was measured by flow cytometry. Neutrophils were identified by their scatter properties and by staining with anti-Ly6G mAb. Results are plotted as the ratio of PKH-26-labeled neutrophils from the indicated genotype to PKH-67-labeled WT neutrophils. The data represent the mean ± SEM from 5 to 8 mice in each experimental group. *P < .05, as determined by unpaired Student test.