Identification of immunogenic epitopes of GAD 65 presented by Ag7 in non-obese diabetic mice.
The autoantigen glutamic acid decarboxylase 65 (GAD 65) is believed to be an important target antigen in insulin-dependent diabetes mellitus (IDDM), since an age-related spontaneous breakdown in tolerance is observed, and cell-mediated and autoantibody immune responses have been reported in humans and NOD mice. We sought to identify immunogenic epitopes of GAD 65 which are presented to T cells by the type I diabetes susceptibility allele (Ag7), using overlapping 15-mer synthetic peptides spanning the entire sequence of this protein. Four epitopes (p206 - 220, p221 - 235, p286 - 300, p571 - 585) were identified by screening a panel of T-cell hybridomas generated from GAD 65-immunized NOD mice. These immunogenic epitopes are unrelated to the previously described T-cell epitopes of GAD 65 reported in NOD mice. Of the GAD 65 amino acid sequence, 206 - 220 and 221 - 235 are the two most dominant T-cell epitopes identified in this study. Sixty-three percent and 25% of GAD 65-responding T cell hybridomas react to p206 - 220 and p221 - 235, respectively. The remaining two peptides (p286 - 300, p571 - 585) are less dominant T-cell responses. The identification of the whole spectrum of GAD 65 Ag7 epitopes should further the investigation of the role of this autoantigen in the pathogenesis of IDDM.
Chao
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Department of Microbiology, Stanford University Medical Center, California 94305, USA.
McDevitt
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D000483:Alleles; D000595:Amino Acid Sequence; D000818:Animals; D017951:Antigen Presentation / Q000235:genetics; D001324:Autoantigens / Q000737:chemistry* / Q000378:metabolism; D018604:Epitope Mapping; D005260:Female; D005968:Glutamate Decarboxylase / Q000737:chemistry / Q000276:immunology*; D000949:Histocompatibility Antigens Class II / Q000235:genetics*; D006825:Hybridomas / Q000737:chemistry / Q000201:enzymology; D016056:Immunodominant Epitopes / Q000737:chemistry* / Q000378:metabolism; D051379:Mice; D016688:Mice, Inbred NOD; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry / Q000276:immunology; D013601:T-Lymphocytes / Q000737:chemistry / Q000201:enzymology
D001324:Autoantigens; D000949:Histocompatibility Antigens Class II; D016056:Immunodominant Epitopes; D010455:Peptides; D005968:Glutamate Decarboxylase