Anti-Platelet Factor 4 Antibody, clone 197.2 clone 197.2, from mouse

Platelet factor 4 (UniProt P02776; also known as C-X-C motif chemokine 4, Iroplact, Oncostatin-A, PF-4) is encoded by the PF4 (also known as CXCL4, SCYB4) gene (Gene ID 5196) in human. Platelet factor 4 (PF4) is a small CXC chemokine family cytokine released from alpha-granules of activated platelets during platelet aggregation to promote blood coagulation. PF4 binds heparin with high affinity (Kd ~4-20 nM) via its heparin-binding domain (a.a. 92-98) and neutralizes the anti-thrombin activity of heparin-like molecules. PF4 is chemotactic for neutrophils, fibroblasts and monocytes, and interacts with the chemokine receptor CXCR3 splice variant CXCR3B. In individuals suffering from heparin-induced thrombocytopenia (HIT), PF4-heparin complexes can trigger an immune response and the generation of anti-PF4 antibodies, resulting in the foramtion of macromolecular antibody-heparin-PF4 immune complexes that bind Fc RIIa (CD32a) on platelets and induce platelet activation. Platelet activation in turn results in more PF4 release into circulation, enhanced immune-complex formation, exaggerated platelet activation, and cell clearance. PF4 is synthesized with a signal peptide sequence (a.a. 1-31) that is removed posttranslationally to produce the mature PF4 (a.a. 32-101), additional proteolytic cleavage yields the PF4 short form (a.a. 48-101).