A simplified method to assess affinity of insulin autoantibodies

Clin Immunol. 2010 Dec;137(3):415-21. doi: 10.1016/j.clim.2010.09.002.


Insulin autoantibodies (IAA) precede type 1 diabetes, but not all IAA-positive children develop other islet autoantibodies and disease. Diabetes risk can be stratified by laborious IAA affinity measurement using competition with multiple ligand concentrations. Here, we identify a single competitor concentration that discriminates low- and high-affinity IAA. Discrimination was achieved among 122 IAA-positive sera using 7.0 nM competitor which is 54-fold that of the assay radioligand concentration. Relative-binding <60% at this competitor concentration identified all 85 sera with affinities ≥1.0×10⁸ L/mol and none with lower affinities (P<0.0001), and 45 (96%) of 47 multiple islet autoantibody-positive sera (P<0.0001). IAA competition was further tested in a second set of 119 IAA-positive sera. Of these, 99 fulfilled high-affinity competition criteria of <60% relative-binding at 7.0 nM competitor including 89 (94%) of 95 sera with multiple islet autoantibodies (P<0.0001). Thus, increased IAA specificity can be achieved with simple modification to existing assays.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Autoantibodies / blood*
  • Child
  • Child, Preschool
  • Diabetes Mellitus, Type 1 / blood
  • Diabetes Mellitus, Type 1 / immunology*
  • Feasibility Studies
  • Female
  • Germany
  • Humans
  • Infant
  • Insulin Antibodies / blood*
  • Islets of Langerhans / immunology*
  • Male
  • Predictive Value of Tests
  • Radioligand Assay
  • Young Adult


  • Autoantibodies
  • Insulin Antibodies