Effect of CD18 blocking mAb on neutrophil mobilization stimulated by MIP-2. (A-D) Cell surface expression of CD11b and CD11a was determined on neutrophils from a nonperfused bone marrow (BM) and those mobilized from the femoral bone marrow in response to a 10-minute infusion of vehicle (Veh.) or MIP-2 (1 nM) using the in situ perfusion system. (A,C) Expression of CD11b and CD11a is shown by the solid histogram, and binding of the isotype-matched control mAb (ic) is shown by the dotted line. Histograms are representative of n = 3 to 7 separate perfusions with staining performed in triplicate. (B,D) Combined results are expressed as the mean of the specific geomeans ± SEMs. (E,F) Using the in situ perfusion system the rat femoral bone marrow was infused with anti-CD18 mAb, WT-3 (10 μg/mL), or an isotype-matched control mAb (10 μg/mL) for 30 minutes, MIP-2 (1 nM) or vehicle were infused for 10 minutes, as indicated by the solid bars. (E) The kinetics of neutrophil mobilization (○, vehicle + IgG; □, vehicle + WT-3; •, MIP-2 + IgG; ▪, MIP-2 + WT-3) and (F) the total number of neutrophils mobilized, mean ± SEM (n = 4 separate perfusions). ^*P < .05 for all panels.