Platelet-Activating Anti–Platelet Factor 4 Disorders

gene, anti-adenovirus protein VII antibody specificity shifts to PF4 by way of a specific somatic hypermutation (K31E) that creates VITT antibodies. In VITT-like monoclonal gammopathy of thrombotic significance, monoclonal anti-PF4 antibodies cause chronic prothrombotic conditions. Accurate diagnosis relies on distinct assays for HIT and VITT antibodies. Beyond anticoagulation, inhibition of FcγIIa receptor-mediated platelet activation may be needed for anti-PF4 disorders with heparin-independent reactivity (e.g., high-dose immune globulin in acute disease manifestations and Bruton's tyrosine kinase inhibitors in chronic manifestations).