title: IA-2 autoantibodies restricted to the IgG4 subclass are associated with protection from type 1 diabetes.
abstract: The tyrosine phosphatase-like protein IA-2 is a major target antigen for autoantibodies in the preclinical period of type 1 diabetes. In this study, we examined whether immunoglobulin isotypes and IgG subclass specific autoantibodies directed at IA-2 discriminate between children at risk of type 1 diabetes who progressed to diabetes vs. those who remained diabetes-free. IgG1-4, IgA and the IgE-specific IA-2 antibody (IA-2A) were measured by radioligand assays in 50 patients with type 1 diabetes and 41 ICA-positive siblings of patients with type 1 diabetes who were followed for diabetes development. Of 41 siblings, 32 were positive for IA-2A; of these, 59 % had IA-2 IgG1, 59 % IgG4, 16 % IgG3, 9 % IgG2, 16 % IgA and 13 % IgE antibodies. IA-2 IgG1 was the dominant isotype in prediabetic children (n = 14, 86 % positive) and patients with type 1 diabetes (98 % positive) whereas only 7 of 18 (39 %) non-progressors had antibodies of this isotype. In subjects that remained diabetes-free, a significantly higher frequency of IA-2 IgG4 in the absence of IgG1 was observed (50 %) compared to progressors (7 %) and patients with type 1 diabetes (0 %). Life-table analysis revealed that IA-2A restricted to IgG4 correlated with protection from type 1 diabetes (p < 0.003). In contrast, IA-2 IgG2, IgG3, IgE and IgA did not differ significantly between study groups. Our findings suggest that the measurement of IA-2 IgG1 and IgG4 subclass antibodies can serve as surrogate marker to discriminate between antibody positive subjects at high or low risk for rapid development of diabetes.
authors: German Diabetes Research Institute, University of Düsseldorf, Auf'm Hennekamp 65, 40225 Düsseldorf, Germany. seissler@ddfi.uni-duesseldorf.de
authors: J
authors: J
authors: Seissler
authors: K
authors: K
authors: Eikamp
authors: M
authors: M
authors: Schott
authors: W A
authors: WA
authors: Scherbaum
mesh_terms: D000293:Adolescent; D001323:Autoantibodies / Q000097:blood / Q000276:immunology*; D002648:Child; D002675:Child, Preschool; D003922:Diabetes Mellitus, Type 1 / Q000235:genetics / Q000276:immunology*; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood / Q000145:classification* / Q000276:immunology; D007132:Immunoglobulin Isotypes; D007223:Infant; D015993:Life Tables; D008297:Male; D011236:Prediabetic State / Q000276:immunology*; D035781:Siblings
chemical_list: D001323:Autoantibodies; C096322:ICA512 autoantibody; D007074:Immunoglobulin G; D007132:Immunoglobulin Isotypes