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. Author manuscript; available in PMC: 2013 Dec 1.
Published in final edited form as: Hum Immunol. 2012 Jul 10;73(12):1233–1238. doi: 10.1016/j.humimm.2012.06.011

Figure 1.

Figure 1

The laminar flow of blood in arteries and arterioles causes platelets to be more concentrated adjacent to the vessel wall. As illustrated in the inset, alloantibodies cause exocytosis of von Willebrand factor (vWf) from storage granules in endothelial cells. Platelets bind to vWf and become activated. Activated platelets release chemokines from their alpha granules and express P-selectin on their membranes. Heteromers of PF4 and RANTES recruit monocytes, which are further activated by PSGL-1 receptors binding to P-selectin on platelets. Complement activation products provide additional chemoatraction (C3a and C5a) as well as ligands (C3b for CR1) to increase leukocyte localization to the endothelium.