title: T cells from hemophilia A subjects recognize the same HLA-restricted FVIII epitope with a narrow TCR repertoire.
abstract: Factor VIII (FVIII)-neutralizing antibodies ("inhibitors") are a serious problem in hemophilia A (HA). The aim of this study was to characterize HLA-restricted T-cell responses from a severe HA subject with a persistent inhibitor and from 2 previously studied mild HA inhibitor subjects. Major histocompatibility complex II tetramers corresponding to both of the severe HA subject's HLA-DRA-DRB1 alleles were loaded with peptides spanning FVIII-A2, C1, and C2 domains. Interestingly, only 1 epitope was identified, in peptide FVIII2194-2213, and it was identical to the HLA-DRA*01-DRB1*01:01-restricted epitope recognized by the mild HA subjects. Multiple T-cell clones and polyclonal lines having different avidities for the peptide-loaded tetramer were isolated from all subjects. Only high- and medium-avidity T cells proliferated and secreted cytokines when stimulated with FVIII2194-2213T-cell receptor β (TCRB) gene sequencing of 15 T-cell clones from the severe HA subject revealed that all high-avidity clones expressed the same TCRB gene. High-throughput immunosequencing of high-, medium-, and low-avidity cells sorted from a severe HA polyclonal line revealed that 94% of the high-avidity cells expressed the same TCRB gene as the high-avidity clones. TCRB sequencing of clones and lines from the mild HA subjects also identified a limited TCRB gene repertoire. These results suggest a limited number of epitopes in FVIII drive inhibitor responses and that the T-cell repertoires of FVIII-responsive T cells can be quite narrow. The limited diversity of both epitopes and TCRB gene usage suggests that targeting of specific epitopes and/or T-cell clones may be a promising approach to achieve tolerance to FVIII.
authors.affiliation: Bloodworks Northwest Research Institute, Seattle, WA.
authors.forename: Ruth A
authors.initials: RA
authors.lastname: Ettinger
authors.affiliation: Bayer Healthcare, South San Francisco, CA.
authors.forename: Pedro
authors.initials: P
authors.lastname: Paz
authors.affiliation: Benaroya Research Institute, Seattle, WA.
authors.forename: Eddie A
authors.initials: EA
authors.lastname: James
authors.affiliation: Bloodworks Northwest Research Institute, Seattle, WA.|Uniformed Services University of the Health Sciences, Bethesda, MD.
authors.forename: Devi
authors.initials: D
authors.lastname: Gunasekera
authors.affiliation: Bayer Healthcare, South San Francisco, CA.
authors.forename: Fred
authors.initials: F
authors.lastname: Aswad
authors.affiliation: Bloodworks Northwest Research Institute, Seattle, WA.|Division of Hematology, Department Medicine, and.
authors.forename: Arthur R
authors.initials: AR
authors.lastname: Thompson
authors.affiliation: Pediatric Hematology/Oncology, University of Washington, Seattle, WA; and.|Blood Disorders Program, Seattle Children's Hospital, Seattle, WA.
authors.forename: Dana C
authors.initials: DC
authors.lastname: Matthews
authors.affiliation: Bloodworks Northwest Research Institute, Seattle, WA.|Uniformed Services University of the Health Sciences, Bethesda, MD.|Division of Hematology, Department Medicine, and.
authors.forename: Kathleen P
authors.identifier: 0000-0001-6837-6133
authors.initials: KP
authors.lastname: Pratt
mesh_terms: D000293:Adolescent; D001323:Autoantibodies / Q000235:genetics / Q000276:immunology; D019774:Blood Coagulation Factor Inhibitors / Q000235:genetics / Q000276:immunology; D002648:Child; D002675:Child, Preschool; D018984:Epitopes, T-Lymphocyte / Q000235:genetics / Q000276:immunology; D005169:Factor VIII / Q000235:genetics / Q000276:immunology; D006680:HLA Antigens / Q000235:genetics / Q000276:immunology; D006467:Hemophilia A / Q000235:genetics / Q000276:immunology; D006801:Humans; D008297:Male; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000235:genetics / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D001323:Autoantibodies; D019774:Blood Coagulation Factor Inhibitors; D018984:Epitopes, T-Lymphocyte; D006680:HLA Antigens; D016693:Receptors, Antigen, T-Cell, alpha-beta; C078147:F8 protein, human; D005169:Factor VIII