Evaluation of Biochemical Characteristics and Performance of the 3 Screen ICA ELISA Kit.

We conducted a fundamental evaluation of the 3 Screen ICA ELISA kit, which can simultaneously measure three major anti-islet autoantibodies important in diagnosing and predicting type 1 diabetes, to assess its usefulness as a measuring reagent. In autoantibody-positive samples, the coefficient of variation for intra-assay variation ranged from 1.37% to 2.50%, inter-assay variation from 2.81% to 3.61%, and lot-to-lot variation from 2.01% to 8.61%, demonstrating good reproducibility. Additionally, interfering substances did not affect the autoantibody titers, and satisfying performance was observed in tests examining the sample freeze-thaw stability. Notably, even when the titer of GAD autoantibodies was below the cut-off value of the GAD autoantibody ELISA, the 3 Screen ICA signal was completely absorbed by recombinant GAD65 protein, indicating that the detection sensitivity for GAD autoantibody in the 3 Screen ICA ELISA is higher than that of the GAD autoantibody ELISA kit. Furthermore, in a study using IASP2020 samples from the Immunology and Diabetes Society, which aims to standardize anti-islet autoantibody assays, this kit achieved excellent results with a sensitivity of 96.0%, specificity of 100%, and accuracy of 98.57%. Measuring multiple anti-islet autoantibodies in combination is crucial for diagnosing and predicting type 1 diabetes. The ELISA kit used in this study is highly versatile and can be used in any measurement facility, making it extremely useful for routine testing.