title: Distinct IA-2 autoantibody epitope recognition between childhood-onset and adult-onset type 1 diabetes.
abstract: Different autoimmune mechanisms may be involved in childhood- and adult-onset type 1 diabetes. Our aim was to explore the differences in IA-2 autoantibody epitope recognition between childhood- and adult-onset type 1 diabetes. Therefore, in vitro synthesized radiolabeled IA-2ic (amino acid 601-979), IA-2JM (amino acid 557-629), and IA-2PTP (amino acid 630-979) were used to analyze the IA-2 autoantibody epitope specificities in 93 patients with new-onset type 1 diabetes. Among 93 patients with type 1 diabetes the prevalences of autoantibodies to GAD, IA-2ic, and insulin were 69.9%, 58.1%, and 45.2%, respectively. The prevalence of IA-2ic autoantibodies in patients with childhood-onset type 1 diabetes (aged <or=18 years, n = 60) was significantly higher than that in patients with adult-onset diabetes (68.3 vs. 36.4%, P < 0.002). Ninety-two percent of type 1 diabetic patients positive for IA-2ic autoantibodies recognized the PTP domain of IA-2, whereas 8% reacted with the JM region only. Among 60 patients with childhood-onset type 1 diabetes, 2% recognized the JM region only, 48% bound the PTP domain of IA-2 only, and 18% recognized both JM and PTP epitopes. Among 33 patients with adult-onset diabetes, 9% recognized the IA-2JM only, 18% bound the IA-2PTP only, and 9% recognized both the IA-2JM and the IA-2PTP. IA-2PTP autoantibodies were prevalent in patients with childhood-onset type 1 diabetes. By contrast, the proportion of patients with the IA-2JM autoantibody only in type 1 diabetes who were positive for IA-2ic autoantibodies was significantly higher in adult-onset than in childhood-onset diabetes (P < 0.05). These results demonstrate that autoantibody recognition of the IA-2 epitope is distinct in childhood-onset and adult-onset type 1 diabetes.
authors.affiliation: The First Department of Internal Medicine, Nagasaki University School of Medicine, Nagasaki 852-8501, Japan. f1196@cc.nagasaki-u.ac.jp
authors.forename: Eiji
authors.initials: E
authors.lastname: Kawasaki
authors.forename: Yasunori
authors.initials: Y
authors.lastname: Sera
authors.forename: Norio
authors.initials: N
authors.lastname: Abiru
authors.forename: Mikako
authors.initials: M
authors.lastname: Yamauchi
authors.forename: Masako
authors.initials: M
authors.lastname: Ozaki
authors.forename: Kenichi
authors.initials: K
authors.lastname: Yamakawa
authors.forename: Takahiro
authors.initials: T
authors.lastname: Abe
authors.forename: Shigeo
authors.initials: S
authors.lastname: Uotani
authors.forename: Hironori
authors.initials: H
authors.lastname: Yamasaki
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Yamaguchi
authors.forename: Katsumi
authors.initials: K
authors.lastname: Eguchi
mesh_terms: D000293:Adolescent; D000328:Adult; D017668:Age of Onset; D000918:Antibody Specificity; D001323:Autoantibodies / Q000276:immunology*; D002648:Child; D003922:Diabetes Mellitus, Type 1 / Q000276:immunology* / Q000503:physiopathology; D003924:Diabetes Mellitus, Type 2 / Q000276:immunology* / Q000503:physiopathology; D000939:Epitopes / Q000276:immunology*; D005260:Female; D005968:Glutamate Decarboxylase / Q000276:immunology; D006801:Humans; D007328:Insulin / Q000276:immunology; D007527:Isoenzymes / Q000276:immunology; D008297:Male; D008875:Middle Aged
chemical_list: D001323:Autoantibodies; D000939:Epitopes; C096322:ICA512 autoantibody; D007328:Insulin; D007527:Isoenzymes; D005968:Glutamate Decarboxylase; C401141:glutamate decarboxylase 2