Platelet factor 4/heparin complexes present epitopes differently on solid-phase vs platelet surfaces

To the editor: The immune response to complexes of the chemokine platelet factor 4 (PF4) and polyanions[1][1],[2][2] results in anti–PF4/polyanion (anti–PF4/P) antibodies, which can induce one of the most frequent immune-mediated adverse drug reactions: heparin-induced thrombocytopenia (HIT).