title: Prediction of HLA class I-restricted T-cell epitopes of islet autoantigen combined with binding and dissociation assays.
abstract: Identification of cognate peptides recognized by human leucocyte antigen (HLA)/T cell receptor (TCR) complex provides insight into the pathogenic process of type 1 diabetes (T1D). We hypothesize that HLA-binding assays alone are inadequate metrics for the affinity of peptides. Zinc transporter-8 (ZnT8) has emerged in recent years as a novel, major, human autoantigen. Therefore, we aim to identify the HLA-A2-restricted ZnT8 epitopes using both binding and dissociation assays. HLA class I peptide affinity algorithms were used to predict candidate ZnT8 peptides that bind to HLA-A2. We analyzed 15 reported epitopes of seven β-cell candidate autoantigens and eight predicted candidate ZnT8 peptides using binding and dissociation assays. Using IFN-γ ELISpot assay, we tested peripheral blood mononuclear cells (PBMCs) from recent-onset T1D patients and healthy controls for reactivity to seven reported epitopes and eight candidate ZnT8 peptides directly ex vivo. We found five of seven recently reported epitopes in Chinese T1D patients. Of the eight predicted ZnT8 peptides, ZnT8(153-161) had a strong binding affinity and the lowest dissociation rate to HLA-A*0201. We identified it as a novel HLA-A*0201-restricted T-cell epitope in three of eight T1D patients. We conclude that ZnT8(153-161) is a novel HLA-A*0201-restricted T-cell epitope. We did not observe a significant correlation (P = 0.3, R = - 0.5) between cytotoxic T cell (CTL) response and peptide/HLA*0201 complex stability. However, selection of peptides based on affinity and their dissociation rate may be helpful for the identification of candidate CTL epitopes. Thus, we can minimize the number of experiments for the identification of T-cell epitopes from interesting antigens.
authors.affiliation: Department of Endocrinology, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu 210029, China.
authors.forename: Xiangmei
authors.initials: X
authors.lastname: Wu
authors.forename: Xinyu
authors.initials: X
authors.lastname: Xu
authors.forename: Rong
authors.initials: R
authors.lastname: Gu
authors.forename: Zhixiao
authors.initials: Z
authors.lastname: Wang
authors.forename: Heng
authors.initials: H
authors.lastname: Chen
authors.forename: Kuanfeng
authors.initials: K
authors.lastname: Xu
authors.forename: Mei
authors.initials: M
authors.lastname: Zhang
authors.forename: John
authors.initials: J
authors.lastname: Hutton
authors.forename: Tao
authors.initials: T
authors.lastname: Yang
mesh_terms: D000328:Adult; D000595:Amino Acid Sequence; D000936:Antigen-Antibody Complex / Q000378:metabolism; D001324:Autoantigens / Q000737:chemistry / Q000276:immunology* / Q000378:metabolism; D015551:Autoimmunity / Q000276:immunology; D027682:Cation Transport Proteins / Q000737:chemistry / Q000276:immunology; D003922:Diabetes Mellitus, Type 1 / Q000276:immunology; D018984:Epitopes, T-Lymphocyte / Q000737:chemistry / Q000276:immunology*; D015789:HLA-A2 Antigen / Q000276:immunology* / Q000378:metabolism; D006801:Humans; D050417:Insulin-Secreting Cells / Q000276:immunology / Q000378:metabolism; D007515:Islets of Langerhans / Q000276:immunology*; D007963:Leukocytes, Mononuclear / Q000276:immunology; D010455:Peptides / Q000737:chemistry / Q000276:immunology; D011485:Protein Binding / Q000276:immunology; D055550:Protein Stability; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology; D055815:Young Adult; D000075703:Zinc Transporter 8
chemical_list: D000936:Antigen-Antibody Complex; D001324:Autoantigens; D027682:Cation Transport Proteins; D018984:Epitopes, T-Lymphocyte; D015789:HLA-A2 Antigen; D010455:Peptides; C492522:SLC30A8 protein, human; D000075703:Zinc Transporter 8