Requirements of P-selectin and phosphatidylserine for the clearance of activated platelets. Glass-adhered platelets were activated with thrombin (0.5 U/mL) for 2 minutes, washed, and incubated either alone (A) or in the presence of purified autologous neutrophils for 2 minutes (B) or 5 minutes (C-E). (D) Platelets were treated with mAb anti–P-selectin before addition of neutrophils. (E) Platelets were treated with recombinant annexin A5 before addition of neutrophils. Glass-adhered, activated platelets were revealed by confocal microscopy after staining with antiplatelet glycoprotein Ib mAbs (red) and neutrophils after staining with the anti-CD66b mAb (green).