Incidence of antibodies to protamine sulfate/heparin complexes in cardiac surgery patients and impact on platelet activation and clinical outcome^{[ * ]}

Summary

A new ELISA (Zymutest HIA^®), based on incubation of diluted plasma with protamine/heparin (PRT/H) complexes without and with platelet factor 4 (PF4) provided by a platelet lysate, was used to detect heparindependent antibodies in a cohort of 232 cardiac surgery (CS) patients and in 47 patients with heparin-induced thrombocytopenia (HIT). Significant binding of IgG/A/M to PRT/H complexes was demonstrated in 59 CS patients (25.4%), with similar absorbances whether platelet lysate was added to the plasma or not, and significant reactivity to PF4/H in 29 of them. Antibodies to PRT or heparin alone were present in 15 and two of these patients, respectively. Importantly, antibodies to PRT/H were detected in only three of the 47 HIT patients, who had also undergone recent CS. The Zymutest HIA^® was positive in another 41 CS patients (17%), but only or mainly when their plasma was tested with platelet lysate, with significant levels of antibodies to PF4/H in 40 of them without detectable reactivity to PRT or heparin alone. Slight antibody binding to PRT/H complexes was also measured in six of these 41 patients. Therefore, a total of 35 CS patients exhibited dual antibody reactivity towards PRT/H and PF4/H complexes. Serotonin release assay performed with PRT alone was positive in 17 CS patients with antibodies to PRT/H, but all had normal platelet count evolution without thrombosis postoperatively. In conclusion, antibodies to PRT/H are frequently present in CS patients postoperatively (25.4%), and can activate platelets in vitro, but their clinical impact remains questionable.

Keywords

Cardiac surgery - Protamine - Heparin-dependent antibodies - Heparin-induced thrombocytopenia

^* An account of this study was presented at the 53rd annual meeting of the American Society of Hematology, San Diego, CA, December 10–13, 2011.

• References

• 1 Warkentin TE, Sheppard JA, Horsewood P. et al. Impact of the patient population on the risk for heparin-induced thrombocytopenia. Blood 2000; 96: 1703-1708.
• 2 Bauer TL, Arepally G, Konkle BA. et al. Prevalence of heparin-associated antibodies without thrombosis in patients undergoing cardiopulmonary bypass surgery. Circulation 1997; 95: 1242-1246.
• 3 Pouplard C, May MA, Iochmann S. et al. Antibodies to platelet factor 4 - Heparin after cardiopulmonary bypass in patients anticoagulated with unfractionated heparin or a low-molecular-weight heparin - Clinical implications for heparininduced thrombocytopenia. Circulation 1999; 99: 2530-2536.
• 4 Linkins LA, Dans AL, Moores LK. et al. Treatment and prevention of heparin-induced thrombocytopenia: Antithrombotic Therapy and Prevention of Thrombosis, 9th ed: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines. Chest 2012; 141: e495S-e530S.
• 5 Carr JA, Silverman N. The heparin-protamine interaction. A review. J Cardiovasc Surg (Torino) 1999; 40: 659-666.
• 6 Chudasama SL, Espinasse B, Hwang F. et al. Heparin modifies the immunogenicity of positively charged proteins. Blood 2010; 116: 6046-6053.
• 7 Nybo M, Madsen JS. Serious anaphylactic reactions due to protamine sulfate: a systematic literature review. Basic Clin Pharmacol Toxicol 2008; 103: 192-196.
• 8 Levy JH, Zaidan JR, Faraj B. Prospective evaluation of risk of protamine reactions in patients with NPH insulin-dependent diabetes. Anesth Analg 1986; 65: 739-742.
• 9 Pouplard C, Leroux D, Regina S. et al. Effectiveness of a new immunoassay for the diagnosis of heparin-induced thrombocytopenia and improved specificity when detecting IgG antibodies. Thromb Haemost 2010; 103: 145-150.
• 10 Pouplard C, Amiral J, Borg JY. et al. Differences in specificity of heparin-dependent antibodies developed in heparin-induced thrombocytopenia and consequences on cross-reactivity with danaparoid sodium. Br J Haematol 1997; 99: 273-280.
• 11 Pouplard C, Darnige L, May MA. et al. Development after cardiopulmonary bypass of antibodies which bind to heparin alone without false positive reactivity to heparin-platelet factor 4 complexes. Blood. 2001 98. 35a (Abstract)
• 12 Suvarna S, Espinasse B, Qi R. et al. Determinants of PF4/heparin immunogenicity. Blood 2007; 110: 4253-4260.
• 13 Weiss ME, Nyhan D, Peng ZK. et al. Association of protamine IgE and IgG antibodies with life-threatening reactions to intravenous protamine. N Engl J Med 1989; 320: 886-892.
• 14 Levy JH. Antibody formation after drug administration during cardiac surgery: parameters for aprotinin use. J Heart Lung Transplant 1993; 12: S26-S33.
• 15 Amiral J, Vissac AM. Pseudo-HIT associated with antibodies to protamine sulfate. J Thromb Haemost. 2009 05. PP-MO-697 (Abstract)
• 16 Bakchoul T, Giptner A, Krautwurst A. et al. Anti-protamine sulphate/PF4 antibodies can activate platelets and may cause thrombocytopenia in patients undergoing cardiac surgery. J Thromb Haemost. 2011 09. (Abstract)
• 17 Butterworth J, Lin YA, Prielipp RC. et al. Rapid disappearance of protamine in adults undergoing cardiac operation with cardiopulmonary bypass. Ann Thorac Surg 2002; 74: 1589-1595.
• 18 Bakchoul T, Zöllner H, Amiral J. et al. Anti-protamine-heparin antibodies: incidence, clinical relevance and pathogenesis. Blood 2013; 121: 2821-2827.
• 19 Lee GM, Welsby IJ, Phillips-Bute B. et al. High incidence of of antibodies to protamine and protamine/complexes in patients undergoing cardiopulmonary bypass. Blood 2013; 121: 2828-2835.
• 20 Liang JF, Yang VC, Vaynshteyn Y. The minimal functional sequence of prota-mine. Biochem Biophys Res Commun 2005; 336: 653-659.