In Vitro Efficacy of Platelet Glycoprotein IIb/IIIa Antagonist in Blocking Platelet Function in Plasma of Patients with Heparin-induced Thrombocytopenia

Summary

Heparin-induced thrombocytopenia (HIT) is an important complication following administration of heparin. Platelet activation and aggregation induced by heparin/platelet factor 4/immunoglobulin complexes are thought to be the underlying mechanism for this condition, so it was hypothesized that abciximab (a humanized murine monoclonal antibody directed against the glycoprotein IIb/IIIa receptor) would prevent heparin-induced platelet aggregation and activation in plasma from patients with HIT. Platelet aggregation was tested in vitro with platelet-poor plasma (obtained from 23 patients with HIT), platelet-rich plasma (from normal donors with known reactivity), heparin (0.5 U/ml), and ascending doses of abciximab (0.07-0.56 μg/ml). The ability of abciximab to prevent platelet activation was also evaluated using flow cytometry (P selectin expression, mepacrine release, microparticle formation) and platelet factor 4 immunoassay. In vitro, abciximab inhibited heparin-induced platelet aggregation in a dose-dependent fashion (IC₅₀ 0.103 μg/ml) and inhibited microparticle formation, the expression of P-selectin, release of mepacrine and platelet factor 4. These findings suggest that abciximab may be useful in treatment of patients with HIT and warrants further clinical evaluation.

• References

• 1 Chong BH. Heparin-induced thrombocytopenia. Aust N Z J Med 1992; 22: 145.
• 2 Leroy J, Leclerc MH, Delahousse B, Guerois C, Foloppe P, Gruel Y, Toulemonde F. Treatment of heparin-associated thrombocytopenia and thrombosis with low molecular weight heparin (CY 216). Semin Thromb Haemost 1985; 11: 326-9.
• 3 Demers C, Ginsberg JS, Brill-Edwards P, Panju A, Warkentin TE, Anderson DR, Turner C, Kelton JG. Rapid anticoagulation using Ancrod for heparin-induced thrombocytopenia. Blood 1991; 78: 2194-7.
• 4 Chong BH, Ismail F, Cade J, Gallus AS, Gordon S, Chesterman CN. Heparin-induced thrombocytopenia: studies with a new low molecular weight heparinoid, Org 10172. Blood 1989; 73: 1592-6.
• 5 Visentin GP, Ford SE, Scott JP, Aster RH. Antibodies from patients with heparin-induced thrombocytopenia/thrombosis are specific for platelet factor 4 complexed with heparin or bound to endothelial cells. J Clin Invest 1994; 93: 81-8.
• 6 Greinacher A, Potzsch B, Amiral J, Dummel V, Eichner A, Mueller-Eckhardt C. Heparin-associated thrombocytopenia: isolation of the antibody and characterization of a multimolecular PF4-heparin complex as the major antigen. Thromb Haemost 1994; 71: 247-51.
• 7 Kelton JG, Smith JW, Warkentin TE, Hayward CPM, Denomme GA, Horsewood P. Immunoglobulin G from patients with heparin-induced thrombocytopenia binds to a complex of heparin and platelet factor 4. Blood 1994; 83: 3232-9.
• 8 Amiral J, Bridey F, Wolf M, Boyer-Neumann C, Fressinaud E, Vissac AM, Peynaud-Debayle E, Dreyfus M, Meyer D. Antibodies to macromolecular platelet factor 4-heparin complexes in heparin-induced thrombocytopenia: a study of 44 cases. Thromb Haemost 1995; 73: 21-8.
• 9 Warkentin TE, Hayward CPM, Boshkov LK, Santos AV, Sheppard J-AI, Bode AP, Kelton JG. Sera from patients with heparin-induced thrombocytopenia generates platelet-derived microparticles with procoagulant activity: an explanation for the thrombotic complications of heparin-induced thrombocytopenia. Blood 1994; 84: 3691-9.
• 10 Adelman B, Sobel M, Fujivora Y, Ruggeri AM, Zimmerman TS. Heparin-associated thrombocytopenia: observations on the mechanism of platelet aggregation. J Lab Clin Med 1989; 113: 204-10.
• 11 Yang L, Blakemore C, Jeske W, Walenga JM, Hoppensteadt D, Fareed J. Glycoprotein IIb/IIIa inhibitors can prevent heparin-mediated platelet activation in heparin-induced thrombocytopenia. Blood 1996; 88 (Suppl. 01) 167a.
• 12 Greinacher A, Liebenhoff U, Kiefel V, Presek P, Mueller-Eckhardt C. Heparin-associated thrombocytopenia: The effects of various IgG preparations on antibody mediated platelet activation – a possible new indication for high dose i.v. IgG. Thromb Haemost 1994; 71: 641-5.
• 13 Aster RH. Heparin-induced thrombocytopenia and thrombosis. N Engl J Med 1995; 332: 1374-6.
• 14 Boshkov LK, Warkentin TE, Hayward CPM, Andrew M, Kelton JG. Heparin-induced thrombocytopenia and thrombosis: clinical and laboratory studies. Br J Haematol 1993; 84: 322-8.
• 15 Coller BS, Folts JD, Scudder LE, Smith SR. Antithrombotic effect of a monoclonal antibody to the platelet glycoprotein IIb/IIIa receptor in an experimental animal model. Blood 1986; 68: 783-6.
• 16 Mak KH, Topol EJ. Platelet glycoprotein IIb/IIIa inhibitors for acute coronary syndromes and percutaneous coronary intervention. In: Textbook of Interventional Cardiology. Topol EJ (ed). Philadelphia: W. B. Saunders; 1996: 345-62.
• 17 Wall JE, Buijs-Wilts M, Arnold JT, Wange W, White MM, Jennings LK, Jackson CW. A flow cytometric assay using mepacrine for study of uptake and release of platelet dense granule contents. Brit J Haematol 1995; 89: 380-5.
• 18 Ramakrishna R, Manoharan A, Kwan YL, Kyle PW. Heparin-induced thrombocytopenia: cross-reactivity between standard heparin, low molecular weight heparin, dalteparin (Fragmin) and heparinoid, danaparoid (Orgaran). Br J Haematol 1995; 91: 736-8.
• 19 Magnani HN. Heparin-induced thrombocytopenia (HIT): An overview of 230 patients treated with Orgaran (Org 10172). Thromb Haemost 1993; 70: 554-61.
• 20 Matsuo T, Kario K, Chikahira Y, Nakao K, Yamada T. Treatment of heparin-induced thrombocytopenia by use of argatroban, a synthetic thrombin inhibitor. Br J Haematol 1992; 82: 627-9.
• 21 Walenga JM, Koza MJ, Lewis BE, Pifarre R. Relative heparin-induced thrombocytopenic potential of low molecular weight heparins and new antithrombotic agents. Clin Appl Thrombosis/Hemostasis 1996; 2 (Suppl. 01) S21-7.
• 22 Warkentin TE, Kelton JG. Interaction of heparin with platelets, including heparin-induced thrombocytopenia. In: Low-Molecular-Weight Heparins in Prophylaxis and Therapy of Thromboembolic Diseases. Bounameaux H, ed. New York: Inc.: Marcel Dekker; 1994. p 75-127.
• 23 Kappa JR, Fisher CA, Addonizio Jr. VP. Heparin-induced platelet activation: the role of thromboxane A2 synthesis and the extent of platelet granule release in 2 patients. J Vasc Surg 1989; 9: 574-9.
• 24 Chong BH, Pilgrim RL, Cooley MA, Chesterman CN. Increased expression of platelet IgG Fc receptors in immune heparin-induced thrombocytopenia. Blood 1993; 81: 988-93.
• 25 Greinacher A. Antigen generation in heparin-associated thrombocytopenia: the nonimmunologic type and the immunologic type are closely linked in their pathogenesis. Semin Thromb Hemostasis 1995; 21: 106-16.
• 26 Kelton JG, Sheridan D, Santos A, Smith J, Steeves K, Smith C, Brown C, Murphy WG. Heparin-induced thrombocytopenia: laboratory studies. Blood 1988; 72: 925-30.
• 27 Chong BH, Ismail F. The mechanism of heparin-induced platelet aggregation. Eur J Haematol 1989; 43: 245-51.
• 28 Coller BS. A new murine monoclonal antibody reports and activation-dependent change in the conformation and/or microenvironment of the platelet glycoprotein IIb/IIIa complex. J Clin Invest 1985; 76: 101-8.
• 29 Mazoyer E, Caen JP, Tenza D, Cramer EM. The anti-aggregating peptide KRDS impairs a granule release, whereas RGDS does not. Platelets 1995; 6: 91-8.