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Comparison of three assays for the detection of GAD65Ab-specific anti-idiotypic antibodies

  • Shilpa Oak
  • Jared Radtke
  • Mona Landin-Olsson
  • Carina Törn
  • Åke Lernmark
  • Christiane S. Hampe
Publishing year: 2009
Language: English
Pages: 55-61
Publication/Series: Journal of Immunological Methods
Volume: 351
Issue: 1-2
Document type: Journal article
Publisher: Elsevier

Abstract english

Anti-idiotypic antibodies (anti-Id) to autoantibodies are present in several autoimmune diseases and are hypothesized to have regulatory function. Recently we reported the presence of anti-Id to a major type 1 diabetes-associated autoantibody (CAD65Ab) in sera of healthy individuals. Our current assay for the detection of GAD65Ab-specific anti-Id requires the initial removal of anti-Id from the sera using immobilized monoclonal GAD65Ab, followed by detection of the now exposed GAD65Ab. However, anti-Id in samples that are GAD65Ab-negative cannot be detected in this assay. Furthermore, we cannot distinguish between serum GAD65Ab and the monoclonal GAD65Ab used in the absorption of anti-Id. In this study we evaluated two novel detection assays for GAD65Ab-specific anti-Id. The biotin/streptavidin based absorption assay utilizes the strong interaction of biotin and streptavidin to prevent possible leakage of the immobilized antibody. Moreover, this assay format allows to identify the origin of the detected GAD65Ab. The ECL-based assay allows the direct detection of anti-Id independent of the presence of GAD65Ab. We analyzed new-onset type 1 diabetes patients (n = 133) and matched healthy controls (n = 178) for the presence of GAD65Ab-specific anti-Id using both new detection assays and the original absorption assay. We found that all three assays can distinguish between the type 1 diabetes cohort and the healthy control samples. The biotin/streptavidin assay allowed us to positively exclude the monoclonal GAD65Ab as the source of the detected GAD65Ab. While the original absorption assay showed the highest sensitivity and specificity, the ECL format showed the highest peak signal-to-noise ratio and excellent linear correlation, making this assay our first choice for quantification of anti-Id. (C) 2009 Elsevier B.V. All rights reserved.


  • Immunology in the medical area
  • Autoantibodies
  • decarboxylase
  • Glutamate
  • Anti-idiotypic antibodies
  • Radioligand binding assay
  • Type 1 diabetes
  • ECL


  • Diabetes and Celiac Unit
  • ISSN: 1872-7905
E-mail: ake [dot] lernmark [at] med [dot] lu [dot] se

Principal investigator

Diabetes and Celiac Unit

+46 40 39 19 01

+46 70 616 47 79


Jan Waldenströms gata 35, Malmö


Lund University Diabetes Centre, CRC, SUS Malmö, Jan Waldenströms gata 35, House 91:12. SE-214 28 Malmö. Telephone: +46 40 39 10 00