title: Structure of a factor VIII C2 domain-immunoglobulin G4kappa Fab complex: identification of an inhibitory antibody epitope on the surface of factor VIII.
abstract: The development of an immune response to infused factor VIII is a complication affecting many patients with hemophilia A. Inhibitor antibodies bind to antigenic determinants on the factor VIII molecule and block its procoagulant activity. A patient-derived inhibitory immunoglobulin G4kappa antibody (BO2C11) produced by an immortalized memory B-lymphocyte cell line interferes with the binding of factor VIII to phospholipid surfaces and to von Willebrand factor. The structure of a Fab fragment derived from this antibody complexed with the factor VIII C2 domain was determined at 2.0 A resolution. The Fab interacts with solvent-exposed basic and hydrophobic side chains that form a membrane-association surface of factor VIII. This atomic resolution structure suggests a variety of amino acid substitutions in the C2 domain of factor VIII that might prevent the binding of anti-C2 inhibitor antibodies without significantly compromising the procoagulant functions of factor VIII.
authors: Graduate Program in Biomolecular Structure and Design, University of Washington, and Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA, USA.
authors: P C
authors: PC
authors: Spiegel
authors: M
authors: M
authors: Jacquemin
authors: J M
authors: JM
authors: Saint-Remy
authors: B L
authors: BL
authors: Stoddard
authors: K P
authors: KP
authors: Pratt
mesh_terms: D000911:Antibodies, Monoclonal / Q000737:chemistry / Q000378:metabolism; D000936:Antigen-Antibody Complex / Q000737:chemistry*; D001402:B-Lymphocytes / Q000276:immunology; D001667:Binding, Competitive; D002460:Cell Line; D018360:Crystallography, X-Ray; D018604:Epitope Mapping; D005169:Factor VIII / Q000276:immunology*; D006467:Hemophilia A / Q000276:immunology; D006801:Humans; D007140:Immunoglobulin Fab Fragments / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D007700:Kinetics; D008958:Models, Molecular; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D014841:von Willebrand Factor / Q000378:metabolism
chemical_list: D000911:Antibodies, Monoclonal; D000936:Antigen-Antibody Complex; D007140:Immunoglobulin Fab Fragments; D014841:von Willebrand Factor; D005169:Factor VIII