title: Assessment of CD4+ T cell responses to glutamic acid decarboxylase 65 using DQ8 tetramers reveals a pathogenic role of GAD65 121-140 and GAD65 250-266 in T1D development.
abstract: Susceptibility to type 1 diabetes (T1D) is strongly associated with MHC class II molecules, particularly HLA-DQ8 (DQ8: DQA1*03:01/DQB1*03:02). Monitoring T1D-specific T cell responses to DQ8-restricted epitopes may be key to understanding the immunopathology of the disease. In this study, we examined DQ8-restricted T cell responses to glutamic acid decarboxylase 65 (GAD65) using DQ8 tetramers. We demonstrated that GAD65 121-140 and GAD65 250-266 elicited responses from DQ8+ subjects. Circulating CD4+ T cells specific for these epitopes were detected significantly more often in T1D patients than in healthy individuals after in vitro expansion. T cell clones specific for GAD65 121-140 and GAD65 250-266 carried a Th1-dominant phenotype, with some of the GAD65 121-140-specific T cell clones producing IL-17. GAD65 250-266-specific CD4+ T cells could also be detected by direct ex vivo staining. Analysis of unmanipulated peripheral blood mononuclear cells (PBMCs) revealed that GAD65 250-266-specific T cells could be found in both healthy and diabetic individuals but the frequencies of specific T cells were higher in subjects with type 1 diabetes. Taken together, our results suggest a proinflammatory role for T cells specific for DQ8-restricted GAD65 121-140 and GAD65 250-266 epitopes and implicate their possible contribution to the progression of T1D.
authors.affiliation: Benaroya Research Institute at Virginia Mason, Seattle, WA, United States of America.
authors.forename: I-Ting
authors.initials: IT
authors.lastname: Chow
authors.affiliation: Benaroya Research Institute at Virginia Mason, Seattle, WA, United States of America.
authors.forename: Junbao
authors.initials: J
authors.lastname: Yang
authors.affiliation: Benaroya Research Institute at Virginia Mason, Seattle, WA, United States of America.
authors.forename: Theresa J
authors.initials: TJ
authors.lastname: Gates
authors.affiliation: Benaroya Research Institute at Virginia Mason, Seattle, WA, United States of America.
authors.forename: Eddie A
authors.initials: EA
authors.lastname: James
authors.affiliation: Benaroya Research Institute at Virginia Mason, Seattle, WA, United States of America.
authors.forename: Duy T
authors.initials: DT
authors.lastname: Mai
authors.affiliation: Benaroya Research Institute at Virginia Mason, Seattle, WA, United States of America.
authors.forename: Carla
authors.initials: C
authors.lastname: Greenbaum
authors.affiliation: Benaroya Research Institute at Virginia Mason, Seattle, WA, United States of America; Department of Medicine, University of Washington, Seattle, WA, United States of America.
authors.forename: William W
authors.initials: WW
authors.lastname: Kwok
mesh_terms: D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D003922:Diabetes Mellitus, Type 1 / Q000276:immunology / Q000503:physiopathology*; D005968:Glutamate Decarboxylase / Q000009:adverse effects* / Q000378:metabolism; D006683:HLA-DQ Antigens / Q000235:genetics*; D006801:Humans; D018709:Statistics, Nonparametric; D014861:Washington
chemical_list: D006683:HLA-DQ Antigens; C109756:HLA-DQ8 antigen; D005968:Glutamate Decarboxylase