title: Islet cell antibody frequency differs from that of glutamic acid decarboxylase antibodies/IA2 antibodies after diagnosis of diabetes.
abstract: The combination of glutamic acid decarboxylase (GAD) 65 antibodies (GADA) and protein tyrosine phosphatase-like protein IA2 antibodies (IA2-ab), measured by radioligand binding assays, has been suggested to replace islet cell antibodies (ICA), measured by indirect immunofluorescence, as a marker for autoimmune type I diabetes. The aim of this study was to compare the frequency of ICA and GADA and/or IA2-ab not only at, but also after the diagnosis of diabetes. ICA, GADA and IA2-ab were therefore assessed at and up to 11 y after the diagnosis of diabetes in 86 children (1-15-y-old). At diagnosis, ICA were found in 74 (86%) and GADA and/or IA2-ab in 79 (92%) of the diabetic children. Hence, there was no major difference in frequency between ICA and GADA and/or IA2-ab at diagnosis of diabetes. At follow-up, however, ICA were less frequent than GADA and/or IA2-ab; 1-3 y after diagnosis ICA were found in 12 (44%) and GADA and/or IA2-ab in 24 (89%) of 27 children (p=0.001); 4-6 y after diagnosis ICA were found in 7 (24%) and GADA and/or IA2-ab in 27 (93%) of 29 children (p < 0.0001); 7-11 y after diagnosis ICA were found in 4 (13%) and GADA and/or IA2-ab in 21 (70%) of 30 children (p < 0.0001). We conclude that the frequency of ICA does not always correspond to that of GADA and/or IA2-ab. Many years after diagnosis of diabetes, measurements of GADA and IA2-ab, but not ICA, detect autoimmunity in high frequency.
authors.affiliation: Department of Endocrinology, University of Lund, Malmö University Hospital, Malmö, Sweden. Henrik.Borg@medforsk.mas.lu.se
authors.forename: H
authors.initials: H
authors.lastname: Borg
authors.forename: C
authors.initials: C
authors.lastname: Marcus
authors.forename: S
authors.initials: S
authors.lastname: Sjöblad
authors.forename: P
authors.initials: P
authors.lastname: Fernlund
authors.forename: G
authors.initials: G
authors.lastname: Sundkvist
mesh_terms: D000293:Adolescent; D001323:Autoantibodies / Q000032:analysis*; D015551:Autoimmunity; D015415:Biomarkers; D002648:Child; D002675:Child, Preschool; D003627:Data Interpretation, Statistical; D003922:Diabetes Mellitus, Type 1 / Q000175:diagnosis* / Q000276:immunology*; D005455:Fluorescent Antibody Technique; D005500:Follow-Up Studies; D005968:Glutamate Decarboxylase / Q000276:immunology*; D006801:Humans; D007223:Infant; D007515:Islets of Langerhans / Q000276:immunology*; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1; D017027:Protein Tyrosine Phosphatases / Q000276:immunology*; D011863:Radioimmunoassay; D012680:Sensitivity and Specificity; D013997:Time Factors
chemical_list: D001323:Autoantibodies; D015415:Biomarkers; D054562:Protein Tyrosine Phosphatase, Non-Receptor Type 1; D017027:Protein Tyrosine Phosphatases; D005968:Glutamate Decarboxylase