Abstract 2825 Structural Basis of PF4 Tetramer Asymmetry Revealed by NMR

Platelet factor 4 (PF4) is a chemokine with diverse biological functions, associated with conditions such as heparin-induced thrombocytopenia (HIT), COVID-19 vaccine-induced immune thrombotic thrombocytopenia (VITT), and various infectious diseases. HIT, in particular, is a potentially fatal complication of heparin-based therapies and is caused by the formation of ultra-large complexes between PF4 tetramers, heparin and specific IgG antibodies. Heparin binds at one end of the asymmetric PF4 tetramers, while IgGs target the opposite end.