title: Discontinuous epitopes on the C2 domain of coagulation Factor VIII mapped by computer-designed synthetic peptides.
abstract: The occurrence of alloantibodies against Factor VIII (FVIII) is the main iatrogenic complication in haemophilia A (HA). Anti-FVIII autoantibodies may also spontaneously appear in non-HA patients, leading to acquired haemophilia A. In both contexts, the antibody response against FVIII is complex and difficult to analyse due to the lack of suitable tools. Our purpose was to comprehensively map, at the amino acid level, discontinuous epitopes of the C2 domain of FVIII targeted by patients' antibodies. We synthesized 33 synthetic peptides, which were predicted by the bioinformatic algorithm PEPOP to mimic C2 domain discontinuous epitopes. Using an inhibition assay based on the x-MAP technology, we evaluated their ability to block the binding to the C2 domain of anti-C2 domain antibodies from pooled plasma samples. Nine peptides were thus selected and tested again in individual plasma samples. Our results support the view that C2 domain epitopes are organized as an epitopic mosaic distributed around the molecule, showed that each patient displayed a specific anti-C2 epitopic profile, and confirmed the complexity and variability of the immune response against the C2 domain of FVIII. This ability to finely map epitopes could be further used to follow the antibody specificity modifications over time.
authors.affiliation: UMR 3145 SysDiag CNRS/Bio-Rad, Parc Euromédecine, Montpellier, France.
authors.forename: Aurélien
authors.initials: A
authors.lastname: Lebreton
authors.forename: Violaine
authors.initials: V
authors.lastname: Moreau
authors.forename: Priscilla
authors.initials: P
authors.lastname: Lapalud
authors.forename: Christopher
authors.initials: C
authors.lastname: Cayzac
authors.forename: Sébastien
authors.initials: S
authors.lastname: André
authors.forename: Christophe
authors.initials: C
authors.lastname: Nguyen
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Schved
authors.forename: Géraldine
authors.initials: G
authors.lastname: Lavigne
authors.forename: Claude
authors.initials: C
authors.lastname: Granier
mesh_terms: D000595:Amino Acid Sequence; D001323:Autoantibodies / Q000276:immunology; D019295:Computational Biology; D018604:Epitope Mapping; D000939:Epitopes / Q000032:analysis / Q000276:immunology*; D005169:Factor VIII / Q000737:chemistry / Q000276:immunology* / Q000378:metabolism; D006467:Hemophilia A / Q000097:blood / Q000276:immunology*; D006801:Humans; D007518:Isoantibodies / Q000276:immunology; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010455:Peptides / Q000138:chemical synthesis / Q000276:immunology*; D055550:Protein Stability
chemical_list: D001323:Autoantibodies; D000939:Epitopes; D007518:Isoantibodies; D010455:Peptides; D005169:Factor VIII