1. Neutralisation of factor VIII inhibitors by anti-idiotypes isolated from phage-displayed libraries.
- Author
-
Schmidt A, Brettschneider K, Kahle J, Orlowski A, Becker-Peters K, Stichel D, Schulze J, Braner M, Tampé R, Schwabe D, and Königs C
- Subjects
- Animals, Antibodies, Monoclonal, Murine-Derived immunology, Antibodies, Monoclonal, Murine-Derived therapeutic use, Antibodies, Neutralizing immunology, Antibodies, Neutralizing therapeutic use, Antibody Specificity, Cross Reactions, Disease Models, Animal, Epitope Mapping, Factor VIII genetics, Hemophilia A genetics, Humans, Hybridomas immunology, Immune Tolerance, In Vitro Techniques, Kinetics, Male, Mice, Mice, Knockout, Peptide Library, Single-Chain Antibodies genetics, Single-Chain Antibodies immunology, Single-Chain Antibodies therapeutic use, Antibodies, Anti-Idiotypic immunology, Antibodies, Anti-Idiotypic therapeutic use, Factor VIII antagonists & inhibitors, Factor VIII immunology, Hemophilia A immunology, Hemophilia A therapy
- Abstract
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 anti-idiotypic 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 inhibitor-specific, high-affinity anti-idiotypes can be isolated from phage-displayed 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.
- Published
- 2016
- Full Text
- View/download PDF