NEW APPROACH FOR DETECTION OF HEPARIN DEPENDENT ANTIBODIES AND RISK ASSESSMENT FOR HEPARIN INDUCED THROMBOCYTOPENIA
Abstract number: P-T-319
Amiral1 J.J., Peyrafitte1 M., Catala1 M., Vissac1 A.M.
1RESEARCH, HYPHEN BIOMED SAS, Neuville sur Oise, France
How-to-cite Amiral JJ, Peyrafitte M, Catala M, Vissac AM. NEW APPROACH FOR DETECTION OF HEPARIN DEPENDENT ANTIBODIES AND RISK ASSESSMENT FOR HEPARIN INDUCED THROMBOCYTOPENIA. J Thromb Haemost 2007; 5 Supplement 2: P-T-319
Introduction: A new approach for risk evaluation or diagnosis of Heparin Induced Thrombocytopenia (HIT) was developed. The goal was to measure, in serum or plasma, heparin dependent antibodies, present in antibody-chemokine-heparin complexes formed on "surfaces" exposing heparin, which trigger the clinical complications of HIT, and to mimick the pathogenic mechanisms.
Methods: An Elisa plate is coated with biologically available heparin, through complexes of protamine sulfate with a large excess of heparin or through streptavidin and biotinylated heparin. The tested plasma or serum, diluted 1:100, is introduced in the well in presence of a platelet or a leuco-platelet lysate, as a source of chemokines. If present antibodies form complexes with chemokines and heparin and are detected with peroxydase labelled second antibodies: anti-IgGAM for the whole of antibodies (assessment of HIT risk); anti-IgG for the most pathogenic anbtibodies associated with clinical complications of HIT; anti-IgG, or anti-IgM or anti-IgA for the full isotyping.
Results: We investigated 37 plasmas from patients with clinically characterized or high suspicion of HIT, and positive platelet aggregation tests. The assay was positive or highly positive in 33 out 37 patients (mean A450 = 1.85). It remained negative for all normal plasmas (N=90; A450 = 0.130.06), or for autoimmune disease plasmas (N = 5; A450 < 0.250). Among the positive patients 32 had IgG, alone or associated with IgM (5), IgA (11), or both (5), and 1 had only IgM. When compared to H-PF4 antibodies, a good correlation was observed (r2=0.84).
Conclusions: This assay is easy to perform, very flexible, and offers definite advantages for evaluating the risk of HIT in heparin treated patients, or diagnosing this complication in presence of clinical suspicion. It offers increased specificity and sensitivity. Inasmuch, this original technology can be adapted to individual testing and automated methods.
To cite this abstract use the following format:
Journal of Thrombosis and Haemostasis 2007; Volume 5, Supplement 2: abstract number
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