Heparin-Induced Thrombocytopenia

Heparin-induced thrombocytopenia (HIT) is an immune-mediated adverse drug reaction that results when pathogenic immunoglobulin (Ig)G antibodies are formed that recognize neoepitopes on a “self” protein – platelet factor 4 (PF4) – after PF4 has formed complexes with heparin (1). Multimolecular complexes of heparin, PF4, and IgG form on platelet surfaces (2).Occupancy of the platelet Fcγ IIa receptors by the resulting immune complexes induces …