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Adenosine Diphosphate (ADP) and ADP Receptor Play a Major Role in Platelet Activation/Aggregation Induced by Sera From Heparin-Induced Thrombocytopenia Patients

  • Polgár, János From the Theodor Kocher Institute, University of Berne, Berne, Switzerland and the Institute for Immunology and Transfusion Medicine, Ernst-Moritz-Arndt-University, Greifswald, Germany.
  • Eichler, Petra From the Theodor Kocher Institute, University of Berne, Berne, Switzerland and the Institute for Immunology and Transfusion Medicine, Ernst-Moritz-Arndt-University, Greifswald, Germany.
  • Greinacher, Andreas From the Theodor Kocher Institute, University of Berne, Berne, Switzerland and the Institute for Immunology and Transfusion Medicine, Ernst-Moritz-Arndt-University, Greifswald, Germany.
  • Clemetson, Kenneth J. From the Theodor Kocher Institute, University of Berne, Berne, Switzerland and the Institute for Immunology and Transfusion Medicine, Ernst-Moritz-Arndt-University, Greifswald, Germany.
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  • Blood. - American Society of Hematology. - 1998, vol. 91, no. 2, p. 549-554
Immunology
Cell Biology
Biochemistry
Hematology
English The molecular basis for heparin-induced thrombocytopenia (HIT), a relatively common complication of heparin therapy, is not yet fully understood. We found that pretreatment of platelets with AR-C66096 (formerly FPL 66096), a specific platelet adenosine diphosphate (ADP) receptor antagonist, at a concentration of 100 to 200 nmol/L that blocked ADP-dependent platelet aggregation, resulted in complete loss of platelet aggregation responses to HIT sera. AR-C66096 also totally inhibited HIT serum-induced dense granule release, as judged by measurement of adenosine triphosphate (ATP) release. Apyrase, added to platelets at a concentration that had only minor effects on thrombin- or arachidonic acid-induced aggregation, also blocked completely HIT serum-induced platelet aggregation. Furthermore, AR-C66096 inhibited platelet aggregation and ATP release induced by cross-linking FcγRIIA with specific antibodies. These data show that released ADP and the platelet ADP receptor play a pivotal role in HIT serum-induced platelet activation/aggregation. The thromboxane receptor inhibitor, Daltroban, had no effect on HIT serum-induced platelet activation whereas GPIIb-IIIa antagonists blocked platelet aggregation but had only a moderate effect on HIT serum-induced dense granule release. Pretreatment of platelets with chondroitinases but not with heparinases resulted in concentration dependent inhibition of HIT serum-induced platelet aggregation. These novel data relating to the mechanism of platelet activation induced by HIT sera suggest that the possibility should be examined that ADP receptor antagonists or compounds that inhibit ADP release may be effective as therapeutic agents for the prevention or treatment of complications associated with heparin therapy.
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  • English
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bronze
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https://sonar.ch/global/documents/235084
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