Activation-dependent surface expression of LOX-1 in human platelets

Lectin-like oxidized LDL receptor-1 (LOX-1) was initially identified as an oxidized LDL receptor in aortic endothelial cells. Here we identified LOX-1 mRNA and protein in human platelets in addition to recent findings on the expression in macrophages and smooth muscle cells. The presence of LOX-1 wa s further confirmed in the megakaryocytic cell lines. Flow cytometric analy ses revealed that LOX-1 was exposed on the surface of platelets in an activ ation-dependent manner. Consistently, the activation-dependent binding of O xLDL to platelets was mostly inhibited by anti-LOX-1 antibody. Immunohistoc hemistry of the atherosclerotic plaque from a patient with unstable angina pectoris (UAP) revealed accumulation of LOX-1 protein at the site of thromb us, As LOX-1 recognizes and binds activated platelets, exposure of LOX-1 on activated platelets surface might assist thrombosis formation. (C) 2001 Ac ademic Press.