title: Combined testing of antibody titer and affinity improves insulin autoantibody measurement: Diabetes Antibody Standardization Program.
abstract: The aim of the workshop was to assess whether four laboratories could reproducibly measure insulin autoantibody (IAA) affinity in coded sera from non-diabetic relatives of patients with type 1 diabetes, newly diagnosed patients, and healthy blood donors, and whether combining affinity with autoantibody titer could improve concordance and performance of IAA assays. IAA affinity was measured by competitive binding using constant amounts of Tyr14A [125I] human insulin and increasing quantities of unlabeled human insulin. There was high concordance between laboratories in distinguishing high, moderate, and low affinity IAA, although IAA binding to insulin varied with assay format. Multiple islet autoantibody-positive and patient sera were identified by high affinity IAA regardless of laboratory-designated IAA status. Combining affinity and titer significantly improved sensitivity, specificity, and concordance of IAA measurement. This workshop has demonstrated that different laboratories are able to reproduce IAA affinity results and that considering IAA affinity is likely to improve the diagnostic performance of IAA assays.
authors.affiliation: Diabetes Research Institute, Koelner Platz 1, 80804 Munich, Germany. Peter.Achenbach@lrz.uni-muenchen.de
authors.forename: Peter
authors.initials: P
authors.lastname: Achenbach
authors.forename: Michael
authors.initials: M
authors.lastname: Schlosser
authors.forename: Alistair J K
authors.initials: AJ
authors.lastname: Williams
authors.forename: Liping
authors.initials: L
authors.lastname: Yu
authors.forename: Patricia W
authors.initials: PW
authors.lastname: Mueller
authors.forename: Polly J
authors.initials: PJ
authors.lastname: Bingley
authors.forename: Ezio
authors.initials: E
authors.lastname: Bonifacio
mesh_terms: D000293:Adolescent; D000328:Adult; D000915:Antibody Affinity; D001323:Autoantibodies / Q000097:blood*; D001667:Binding, Competitive; D002648:Child; D002675:Child, Preschool; D003922:Diabetes Mellitus, Type 1 / Q000097:blood* / Q000175:diagnosis; D006801:Humans; D007330:Insulin Antibodies / Q000097:blood*; D008875:Middle Aged; D011869:Radioligand Assay / Q000592:standards*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D001323:Autoantibodies; D007330:Insulin Antibodies