Contribution of distinct adhesive interactions to platelet aggregation in flowing blood

Aggregation of blood platelets contributes to the arrest of bleeding at sit es of vascular injury, but it can occlude atherosclerotic arteries and prec ipitate diseases such as myocardial infarction. The bonds that link platele ts under flow conditions were identified using confocal videomicroscopy in real time. Glycoprotein (GP) Ib alpha and von Willebrand factor (VWF) acted in synergy with alpha(IIb)beta(3) and fibrinogen to sustain platelet accru al at the apex of thrombi where three-dimensional growth resulted in increa sing shear rates. The specific function of distinct adhesion pathways in re sponse to changing hemodynamic conditions helps to explain hemostatic and t hrombotic processes. (C) 1999 by The American Society of Hematology.