Antibodies against platelet factor 4 (PF4), a protein released from alpha-granules of activated platelets, may cause a number of pathophysiological conditions. The most commonly known is heparin-induced thrombocytopenia (HIT), which develops in a ...

Dec 8, 2023 · Antibodies against the chemokine platelet factor 4 (PF4) occur often, but only those that activate platelets induce severe prothrombotic disorders with associated thrombocytopenia.

Dec 10, 2011 · Heparin-induced thrombocytopenia (HIT) is a prothrombotic drug reaction caused by platelet-activating IgG antibodies that recognize platelet factor 4 (PF4)/polyanion complexes.

This ELISA assay detects the presence of IgG antibodies to heparin-platelet factor 4 (PF4) complexes. Most cases of heparin-induced thrombocytopenia (HIT) are caused by IgG antibodies to heparin-PF4, rather than IgA or IgM antibodies.

Platelet factor-4 is a 70-amino acid protein that is released from the alpha-granules of activated platelets and binds with high affinity to heparin. Its major physiologic role appears to be neutralization of heparin-like molecules on the endothelial surface of blood vessels, thereby inhibiting local antithrombin activity and promoting coagulation.

Dec 8, 2020 · Heparin-induced thrombocytopenia (HIT) is a complication of treatment with heparin caused by antibodies. A test for HIT (heparin-PF4) antibody helps diagnosis HIT type II.

Heparin is a commonly used anticoagulant in various clinical settings, and can be given either intravenously or subcutaneously. In HIT, heparin interacts with PF4, a small cytokine belonging to the CXC chemokine family that is also known as CXCL4.

Nov 5, 2024 · Heparin-induced thrombocytopenia (HIT) is a severe complication of heparin therapy, driven by IgG antibodies (Abs) that target platelet factor 4 (PF4) bound to heparin, resulting in platelet activation and a pro-thrombotic state.

Mar 1, 2025 · Presently, only platelet activation assays reliably distinguish anti-PF4/H Abs that cause disease (HIT Abs) from those likely to be asymptomatic (AAbs). Recent studies indicate that complement activation is an important serologic property of HIT Abs and is essential for IgG Fc receptor IIA-mediated cellular activation.

Dec 12, 2018 · Anti-PF4/H Abs are classified into three groups: (i) nonpathogenic Abs (group 1) with no clinical relevance; (ii) pathogenic heparin-dependent Abs (group 2), which activate platelets and can cause the severe adverse drug effect heparin-induced thrombocytopenia (HIT); and (iii) pathogenic autoimmune-HIT Abs (group 3), in which group 3 anti-PF4/H ...