Thrombopénies et thromboses induites par les anticorps anti-FP4

Abstract

AbstractThrombocytopenia and thromboses induced by antibodies to platelet factor 4 (PF4) constitute a heterogeneous group of rare but severe clinical and biological syndromes, including classical heparin-induced thrombocytopenia (HIT), and more rarely autoimmune HIT, vaccine-induced immune thrombotic thrombocy-topenia (VITT), and, recently, VITT-like syndromes. These pathologies all induce major hypercoagulability, related to blood cell activation by anti-PF4 antibodies, leading to potentially severe thromboses, which require urgent treatment. The severity of thrombocytopenia and thromboses, and their location, vary with the disease; autoimmune HIT and VITT are associated with particularly aggressive forms, including cerebral venous thrombosis. The diagnosis of thrombocytope-nia and thromboses induced by anti-PF4 antibodies relies on a combination of clinical and biological factors, including the detection of anti-PF4 antibodies by immunological assays and, in most cases, confirmation of their pathogenicity by platelet activation tests. As the performance of these tools varies greatly depending on the pathology, the biologist plays a major role in the choice of the assays, and their interpretation, to ensure correct diagnosis and appropriate management of the patient.