Thromb Haemost 2016; 116(01): 32-41
DOI: 10.1160/TH15-12-0925
Coagulation and Fibrinolysis
Schattauer GmbH

Neutralisation of factor VIII inhibitors by anti-idiotypes isolated from phage-displayed libraries

Anja Schmidt
1   Molecular Haemostasis and Immunodeficiency, Department of Paediatrics, University Hospital Frankfurt, Frankfurt am Main, Germany
,
Kerstin Brettschneider
1   Molecular Haemostasis and Immunodeficiency, Department of Paediatrics, University Hospital Frankfurt, Frankfurt am Main, Germany
,
Jörg Kahle
1   Molecular Haemostasis and Immunodeficiency, Department of Paediatrics, University Hospital Frankfurt, Frankfurt am Main, Germany
,
Aleksander Orlowski
1   Molecular Haemostasis and Immunodeficiency, Department of Paediatrics, University Hospital Frankfurt, Frankfurt am Main, Germany
,
Karin Becker-Peters
1   Molecular Haemostasis and Immunodeficiency, Department of Paediatrics, University Hospital Frankfurt, Frankfurt am Main, Germany
,
Diana Stichel
1   Molecular Haemostasis and Immunodeficiency, Department of Paediatrics, University Hospital Frankfurt, Frankfurt am Main, Germany
,
Jörg Schulze
2   Department of Internal Medicine I, Research Group PhosphoSites, University Hospital Frankfurt, Frankfurt am Main, Germany
,
Markus Braner
3   Institute of Biochemistry, Biocenter, Goethe University Frankfurt, Frankfurt am Main, Germany
,
Robert Tampé
3   Institute of Biochemistry, Biocenter, Goethe University Frankfurt, Frankfurt am Main, Germany
,
Dirk Schwabe
1   Molecular Haemostasis and Immunodeficiency, Department of Paediatrics, University Hospital Frankfurt, Frankfurt am Main, Germany
,
Christoph Königs
1   Molecular Haemostasis and Immunodeficiency, Department of Paediatrics, University Hospital Frankfurt, Frankfurt am Main, Germany
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Publikationsverlauf

Received: 04. Dezember 2015

Accepted after major revision: 14. März 2016

Publikationsdatum:
27. November 2017 (online)

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Summary

Following replacement therapy with coagulation factor VIII (FVIII), up to 30 % of haemophilia A patients develop FVIII-specific inhibitory antibodies (FVIII inhibitors). Immune tolerance induction (ITI) is not always successful, resulting in a need for alternative treatments for FVIII inhibitor-positive patients. As tolerance induction in the course of ITI appears to involve the formation of anti-idiotypes specific for anti-FVIII antibodies, such anti-idiotypes might be used to restore haemostasis in haemophilia A patients with FVIII inhibitors. We isolated antiidiotypic antibody fragments (scFvs) binding to murine FVIII inhibitors 2-76 and 2-77 from phage-displayed libraries. FVIII inhibitor/anti-idiotype interactions were very specific as no cross-reactivity with other FVIII inhibitors or isotype controls was observed. ScFvs blocked binding of FVIII inhibitors to FVIII and neutralised their cognate inhibitors in vitro and a monoclonal mouse model. In addition, scFv JkH5 specific for FVIII inhibitor 2-76 stained 2-76-producing hybridoma cells. JkH5 residues R52 and Y226, located in complementary determining regions, were identified as crucial for the JkH5/2-76 interaction using JkH5 alanine mutants. SPR spectroscopy revealed that JkH5 interacts with FVIII inhibitor 2-76 with nanomolar affinity. Thus, FVIII inhibitorspecific, high-affinity anti-idiotypes can be isolated from phagedisplayed libraries and neutralise their respective inhibitors. Furthermore, we show that anti-idiotypic scFvs might be utilised to specifically target inhibitor-specific B cells. Hence, a pool of anti-idiotypes could enable the reestablishment of haemostasis in the presence of FVIII inhibitors in patients or even allow the depletion of inhibitors by targeting inhibitor-specific B cell populations.