A New Luminescence Assay For Autoantibodies To Mammalian Cell-Prepared Insulinoma-Associated Protein 2

OBJECTIVE - Insulinoma-associated protein 2 (IA-2) is a major autoantigen in type I 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 (R-2 = 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.