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Keywords:

  • GAD65;
  • IA-2;
  • autoantibody;
  • islet cell autoantibodies;
  • diabetes mellitus

Stocks of the WHO islet cell antibody, GAD65 antibody, and IA-2 antibody standard (NIBSC 97/550) are now very limited. We have therefore made and tested a series of control preparations in which human monoclonal autoantibodies to IA-2 and to GAD65 were diluted in antibody-negative human serum to different concentrations. Three different diabetes autoantibody controls (DAC 1–3) were made as was a negative control preparation. Aliquots containing 1 mL of autoantibodies in serum were freeze-dried. After reconstitution (with 1 mL of water) the controls were tested by 125I-IA-2 immunoprecipitation assay (IPA), 125I-GAD65 IPA, GAD65 Ab ELISA and IA-2 Ab ELISA (kits from RSR Ltd.) and for ICA by immunofluorescence test (IFT). DAC1 is particularly suitable as a control for the 125I IA-2 IPA; DAC2 is suitable for the 125I-GAD65 IPA, GAD65 Ab ELISA, and IA-2 Ab ELISA; and DAC3 is suitable for the ICA IFT. Freeze-dried preparations showed good stability at 37°C. Reconstituted liquid preparations were stable when stored at 4°C and at 37°C. Availability of an essentially unlimited supply of these reagents should be useful in establishing reproducible and comparable measurements of diabetes autoantibodies in different laboratories using different assays.