Heparin-induced thrombocytopenia: laboratory studies.

نویسندگان

  • J G Kelton
  • D Sheridan
  • A Santos
  • J Smith
  • K Steeves
  • C Smith
  • C Brown
  • W G Murphy
چکیده

This report describes studies into the pathophysiology of heparin-induced thrombocytopenia. The IgG fraction from each of nine patients with heparin-induced thrombocytopenia caused heparin-dependent platelet release of radiolabeled serotonin. Both the Fc and the Fab portions of the IgG molecule were required for the platelet reactivity. The platelet release reaction could be inhibited by the Fc portion of normal human or goat IgG, and patient F(ab')2, but not F(ab')2 from healthy controls. These results suggested that the Fab portion of IgG binds to heparin forming an immune complex and the immune complexes initiate the platelet release reaction by binding to the platelet Fc receptors. To directly challenge this hypothesis, we preincubated the serotonin-labeled platelets with the monoclonal antibody against the platelet Fc receptor (IV.3). This monoclonal antibody completely inhibited the release reaction caused by heparin and patient sera, as well as heat aggregated IgG, but did not block collagen or thrombin-induced platelet release. Heparin-dependent platelet release also could be inhibited in vitro by the addition of monocytes and neutrophils, but not by red cells, presumably because the Fc receptors on the phagocytic cells have a higher binding affinity for IgG complexes than do platelets. Platelets from patients with congenital deficiencies of specific glycoproteins Ib and IX (Bernard-Soulier syndrome) and IIb and IIIa (Glanzmann's thrombasthenia) displayed normal heparin-dependent release indicating that the release reaction did not require the participation of these glycoproteins. These studies indicate that heparin-induced thrombocytopenia is an IgG-heparin immune complex disorder involving both the Fab and Fc portion of the IgG molecule.

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منابع مشابه

Heparin induced thrombocytopenia

Abstract Background and Objectives Heparin is still a commonly used anticoagulant in prophylaxis and treatment of thromboembolic events. Heparin-induced thrombocytopenia (HIT) is a life-threating adverse drug reaction of heparin. The diagnosis of HIT is made based on two important criteria, firstly clinical evaluation and secondly laboratory testing. In this comprehensive review, the authors w...

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Diagnosis and management of heparin-induced thrombocytopenia.

PURPOSE To review recent developments in the pathogenesis, clinical features, laboratory testing and treatment of heparin-induced thrombocytopenia (HIT). METHODS Narrative review of the literature, including relevant papers published in English or French. PRINCIPAL FINDINGS Although the prevalence of HIT has decreased with the widespread use of low molecular weight heparin in the past ten y...

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عنوان ژورنال:
  • Blood

دوره 72 3  شماره 

صفحات  -

تاریخ انتشار 1988