Interaction of Platelets, Leukocytes and the Endothelium*

Interactions between the vessel wall and platelets or leukocytes were traditionally thought to be separate cellular adhesive contributions to either coagulation or inflammation. Observations in biological systems and the recent discovery and characterization of the family of junctional adhesion molecules (JAMs) have now clarified that both systems are closely related. This, in retrospective, seems not surprising, as shear stress in the circulation places comparable dynamic and mechanical constraints on the adhesion of both leukocytes and platelets. This review will briefly summarize the molecular basis of the interaction between leukocytes and the endothelium, leukocytes and platelets and platelets and endothelial cells. The main emphasis will be on current data supporting the relevance of JAMs, GPIba and the Mac-1 integrin in these multicellular interactions.