A New Luminescence Assay for Autoantibodies to Mammalian Cell–Prepared Insulinoma-Associated Protein 2

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Abstract
OBJECTIVE—Insulinoma-associated protein 2 (IA-2) is a major autoantigen in type 1 diabetes, and IA-2 autoantibodies are routinely detected by a liquid-phase radioimmunoprecipitation assay. The present experiments were initiated to develop a new assay that does not require the use of radioisotopes or autoantigens prepared in bacteria or by in vitro transcription/translation. RESEARCH DESIGN AND METHODS—IA-2 luciferase fusion protein was expressed in mammalian cells and assayed for autoantibodies by liquid-phase luciferase immunoprecipitation. RESULTS—Our study showed that there was no significant difference between the luciferase immunoprecipitation and the radioimmunoprecipitation assays in sensitivity and specificity, and comparison of the two assays revealed a high correlation coefficient (R2 = 0.805). CONCLUSIONS—The luciferase system offers a robust, inexpensive, nonradioactive method for the detection of autoantibodies to mammalian cell–prepared IA-2 and could be of practical value at the clinical level.