A SIMPLE AND RAPID MICROSEPHAROSE ASSAY FOR GAD65 AND ICA512 AUTOANTIBODIES IN DIABETES

GAD65Ab and ICA512Ab are strongly associated with insulin-dependent (T ype 1) diabetes mellitus. A novel, simple radio-antigen binding assay with microSepharose conjugated with monoclonal antibodies specific for human immunoglobulin light chains was developed to provide diagnostic sensitivity and specificity of GAD65Ab and ICA512Ab for Type 1 diabet es. The Receiver Operating Characteristic (ROC) curve was used to dete rmine the upper level of Normal in 583 new onset Type 1 diabetic patie nts and in 829 matched controls. The sensitivity of GAD65Ab and ICA512 Ab was 66% (384/583) and 41% (211/520), respectively, and the diagnost ic specificity was 96% for both autoantibodies. Levels, but not freque ncy, of GAD65Ab were higher among female Type 1 diabetes patients, whe reas ICA512Ab levels did not differ between males and females. Positiv ity for GAD65Ab, ICA512Ab or both showed a sensitivity of 74% and a sp ecificity of 92% for Type 1 diabetes. This simple, one-step centrifuga tion, high-capacity radio-antigen binding assay has a high precision a nd reproducibility to accurately detect both GAD65Ab and ICA512Ab, Thi s assay should also prove useful in other autoantibody assays against conformation-sensitive autoantigens. (C) 1998 Elsevier Science B.V. Al l rights reserved.