Figure 6. Enhanced recruitment of ADAM17-null neutrophils involves CXCR2. (A) Control and conditional ADAM17-knockout mice were administered LPS i.p. (5 mg/kg). (B) Wild-type mice were administered the ADAM17 inhibitor BMS566394 (BMS; 33 mg/kg) or carrier (see Materials and Methods) and then LPS i.p., 30 min later. After 4 h, neutrophil levels in the peritoneal cavity of all mice were enumerated. The bar graph shows mean ± sd of 3 mice/group or treatment. Control, conditional ADAM17-knockout, and wild-type mice had few, if any, peritoneal neutrophils before LPS administration (data not shown). (C) Mouse peripheral blood neutrophils were stimulated as described in Fig. 1B but in the presence of the CXCR2 inhibitor SB265610 (200 nM) for 30 min at 37°C, which selectively blocked CXCR2 down-regulation by KC-stimulated neutrophils. Negative control antibody staining of untreated cells is indicated (Isotype). Mean fluorescence intensity is indicated in parentheses. The y-axis = cell number. Flow cytometry data are representative of 3 independent experiments by use of leukocytes from separate mice. (D) Control and conditional ADAM17-knockout mice were administered the CXCR2 inhibitor SB265610 (3 mg/kg) or carrier (see Materials and Methods) i.v., 30 min before LPS treatment. After 4 h, peritoneal neutrophil levels were determined. Results are expressed as mean ± sd of 4 mice in each group/treatment. Statistical significance is indicated as *P < 0.05, and **P < 0.01.