Automated Multiplex Antibody Detection by Agglutination PCR (ADAP) Compared with Gold Standard Radiobinding Assays of Autoantibodies in Type 1 Diabetes

Autoantibody biomarkers detect asymptomatic autoimmunity and predict clinical onset of autoimmune type 1 diabetes. Single plex radiobinding assays (RBA) were compared with Antibody Detection by Agglutination PCR (ADAP), a novel minimum volume (4 μL) automated (Hamilton MicroLab STAR), multiplex autoantibody assay. Serum samples from 2,500 incident, 1-18 years of age, newly diagnosed type 1 diabetes patients and 2,500 controls, 1-50 years of age, were analysed for autoantibodies against insulin (IAA), glutamic acid decarboxylase (GADA), islet antigen-2 (IA-2A) and ZnT8 transporter (ZnT8A). RBA for ZnT8A was against position 325 W, R and Q while ADAP was against W and R. Area Under the Curve (AUC) of the Receiver Operating Characteristics (ROC) curves for detection of type 1 diabetes patients showed 1) IAA improved with ADAP compared to RBA; Enable slightly better than CRC; 2) GADA improved with ADAP compared to RBA; no difference between Enable and CRC; 3) IA-2A improved with ADAP compared to RBA; similar performance between Enable and CRC and 4) ZnT8A showed better performance with RBA compared to ADAP; Enable better performance than CRC (Figure). The data suggest that multiplex ADAP, compared to golden standard single plex RBA, should prove useful in large scale, automated multiplex screening for asymptomatic type 1 diabetes. Disclosure A.Lind: None. A.Ramelius: None. E.Freyhult: None. F.Cortez: Employee; Enable Biosciences. R.Bennet: None. H.E.Larsson: None. D.Seftel: Employee; Enable Biosciences, Inc. J.Tsai: Stock/Shareholder; Enable Biosciences. Å.Lernmark: Advisory Panel; Diamyd Medical. Funding The Leona M. and Harry B. Helmsley Charitable Trust (2009-04078)