Arrest of 4N1K-activated platelets on TNF-α–treated endothelial cells incubated with blocking mAbs directed against ICAM-1, αvβ3 integrin, or both. EA endothelial cells were grown onto permanox Lab-Tek 1 chamber slides and stimulated with 25 ng/mL rhTNF-α for 18 hours. Then 40 μg/mL anti–ICAM-1 B-H17, anti-αvβ3 LM609, or both mAbs were added to these cells for 10 minutes at 37°C. They were washed with PBS before being placed in the flow chamber. After platelet labeling in PRP with calceine, platelets were incubated for 15 minutes at 37°C with or without 100-μM 4N1K peptide in solution. Whole blood was then reconstituted and perfused through the chamber at 37°C and at a shear rate of 100 seconds^–1 for 3 minutes. Platelet adhesion, expressed as percentage of surface covered with platelets, is the average ± SEM of 10 random fields per coverslip. ***P < .001. This experiment is representative of 3 experiments performed using blood from different donors.