Description
Platelet factor 4 (PF4/CXCL4) is an ELRˆ' tetrameric, cationic chemokine that constitutes 25% of the protein in platelet alpha-granules. It is also found bound to the luminal vascular endothelial surface. Although platelets represent the primary source of PF4, it is also expressed at lower levels in other cells of the immune system including cultured T cells, monocytes, and endothelial and smooth muscle cells