title: Molecular characterization of human B domain-specific anti-factor VIII monoclonal antibodies generated in transgenic mice.
abstract: The development of antibodies directed against factor VIII (FVIII) represents a major hurdle in the treatment of hemophilia A. Most anti-FVIII antibodies are identified through their ability to inhibit the FVIII procoagulant activity. Many of them, however, do not interfere with the functional properties of FVIII. Antibodies directed against the B domain belong to this latter category. Here, we characterized B domain-specific human monoclonal Abs (mAbs) at the molecular level. A series of human mAbs directed against FVIII was produced upon immunization of transgenic XenoMouse mice with human recombinant FVIII (rFVIII). Selection of the hybridoma with epitope specificity for the B domain was performed by differential recognition of full-length and B domain-deleted rFVIII. None of the anti-B domain mAbs demonstrated inhibitory activity against FVIII. Three of the mAbs recognized linear epitopes: mAb 25H3 bound to the (1014)HIDGPSLLIEN(1024) sequence; mAbs 8E3 and 22B6 shared the same epitope, composed of residues (1534)KWNEANR(1540). The corresponding soluble peptides inhibited the binding of their respective mAbs to FVIII. mAbs 8E3 and 22B6 displaced the binding of FVIII to vonWillebrand factor. Moreover, some of them (in particular mAbs 4G6 and 8E3) were able to compete for binding to the B domain with the anti-FVIII Abs from hemophilia A patients without inhibitor or with low Bethesda titers. Further investigation will allow to better characterize their clinical relevance.
authors.affiliation: CNRS UMR 5160, Faculté de Pharmacie BP 14491, 15 Avenue Charles Flahault, 34093 Montpellier Cedex 5, France.
authors.forename: Géraldine
authors.initials: G
authors.lastname: Lavigne-Lissalde
authors.forename: Sébastien
authors.initials: S
authors.lastname: Lacroix-Desmazes
authors.forename: Bharath
authors.initials: B
authors.lastname: Wootla
authors.forename: Catherine
authors.initials: C
authors.lastname: Tarrade
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Schved
authors.forename: Srini V
authors.initials: SV
authors.lastname: Kaveri
authors.forename: Claude
authors.initials: C
authors.lastname: Granier
authors.forename: Sylvie
authors.initials: S
authors.lastname: Villard-Saussine
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000096:biosynthesis / Q000276:immunology* / Q000494:pharmacology; D001667:Binding, Competitive; D002648:Child; D002675:Child, Preschool; D000939:Epitopes; D005169:Factor VIII / Q000276:immunology* / Q000378:metabolism; D006467:Hemophilia A / Q000276:immunology; D006801:Humans; D006825:Hybridomas / Q000276:immunology; D007223:Infant; D051379:Mice; D008822:Mice, Transgenic; D008875:Middle Aged; D010446:Peptide Fragments / Q000276:immunology; D014841:von Willebrand Factor / Q000378:metabolism
chemical_list: D000911:Antibodies, Monoclonal; D000939:Epitopes; D010446:Peptide Fragments; D014841:von Willebrand Factor; C078147:F8 protein, human; D005169:Factor VIII