PF4 Recombinant Rabbit mAb (S-4220)

Platelet factor 4 (PF4) is a 70–amino-acid, 7.8-kDa CXC chemokine stored in platelet α-granules and released upon activation, where it binds glycosaminoglycans such as heparin with ultra-high affinity, neutralizes the anticoagulant activity of heparin by bridging and clustering it on platelet or endothelial surfaces, and forms stable tetramers that can subsequently assemble into ultra-large immune complexes recognized by anti-PF4/heparin antibodies in heparin-induced thrombocytopenia (HIT), while also exerting broader immune-modulatory effects by recruiting and activating leukocytes, promoting neutrophil extracellular trap (NET) formation, enhancing monocyte adhesion and phagocytosis, and amplifying thrombo-inflammation in conditions such as sepsis, COVID-19, and atherosclerosis through interaction with receptors including CXCR3, TLR4, and FcγRIIA.