Platelet Factor 4 (PF4)

Platelet factor 4 (PF4), also known as chemokine (C-X-C motif) ligand 4 (CXCL4), is a small cytokine and member of the CXC chemokine family. It is synthesized by megakaryocytes and stored in the α-granules of platelets, from which it is released upon platelet activation. PF4 plays roles in coagulation, inflammation, wound healing, and immunity by interacting with heparin, heparan sulfate, CXCR3-B, and c-Mpl, activating downstream signaling pathways. It is clinically relevant in conditions like heparin-induced thrombocytopenia (HIT) and vaccine-induced immune thrombotic thrombocytopenia (VITT).

Other names

Chemokine (C-X-C motif) ligand 4CXCL4

Neutralizes heparin-like molecules, binds GAGs, activates c-Mpl/JAK2 pathway, chemoattractant for neutrophils, fibroblasts, and monocytes