Firm adhesion but not capture and rolling are defective in LAD neutrophils. (A) Neutrophil accumulation and development of firm arrest on TNF-activated HUVECs under physiological shear flow. Leukocytes isolated from a healthy donor (control) or patient (LAD) were perfused for 1 minute at 0.75 dyne/cm² over the HUVEC monolayers, and accumulated leukocytes were subjected to a shear stress of 5 dyne/cm² for a 10-second period. The number of leukocytes remaining adherent that either continued to roll on the monolayer (▦) or came to full arrest (▪) was determined. The values of adherent categories depicted in the figure correspond to fractions of the original leukocyte flux perfused in immediate contact with the endothelial layer. (B) FACS (fluorescence-activated cell sorter) staining of LFA-1 (gray lines) and Mac-1 (solid lines) integrins on control and LAD neutrophils using the mAbs TS2.4 (anti-αL integrin subunit) and CBRM1/2 (anti-αM integrin subunit) as primary antibodies. Background staining is shown by the dotted line. (C) PAF-triggered neutrophil arrest on nonactivated HUVECs. Control or LAD neutrophils were perfused at 0.75 dyne/cm² over unstimulated HUVECs overlaid with PAF (100 nM, 5 minutes of incubation). Arrested cells were determined as in panel A. Where indicated, neutrophils were pretreated with the β2 integrin–blocking mAb TS1.18 (20 μg/mL, 5 minutes, 4°C). Values in panels A and C are given as mean ± range of determinations in 2 fields of view. Because transient tethers comprised less than 10% of the total cell-capturing events, they were not included in the analysis. Results in panels A-C are representative of 3 independent experiments.