Figure 1. CXCR2 regulation in neutrophils by ligand and nonligand stimuli. (A) Peripheral blood neutrophils from wild-type mice were unstimulated (Unstim.) or treated with KC or MIP-2 at the indicated concentrations for 30 min at 37°C. Isotype-negative control antibody staining is indicated by a dotted line. The x-axis = Log 10 fluorescence, and the y-axis = cell number. Flow cytometric data are representative of 3 independent experiments by use of leukocytes from separate mice. (B) Neutrophils were treated with or without KC (200 ng/ml), MIP-2 (200 ng/ml), PMA (200 ng/ml), formyl peptide (FP; 1 μg/ml) or formyl peptide and LPS (1 μg/ml each) for 30 min at 37°C. (C) Neutrophils were stimulated as indicated in the presence of the broad-spectrum metalloprotease inhibitor BB94 (10 μM) or carrier (appropriate DMSO dilution) for 30 min at 37°C. Relative cell-staining levels of CXCR2 antibodies were determined by flow cytometry. MFI, Mean fluorescence intensity. The bar graphs show mean ± sd for at least 3 mice/treatment. Statistical significance is indicated as **P < 0.01, and ***P < 0.001 vs. unstimulated.