3 Screen islet cell autoantibody ELISA: A sensitive and specific ELISA for the combined measurement of autoantibodies to GAD, to IA-2 and to ZnT8.

3 Screen, a new ELISA for the combined measurement of autoantibodies to GAD, to IA-2 and to ZnT8, has been developed and evaluated. In the assay serum samples were incubated (overnight; 2-8°C) in ELISA plate wells coated with GAD, IA-2 and ZnT8 followed by a wash step and incubation with biotinylated GAD, IA-2 and ZnT8 (1h; 2-8°C,). The assay was completed by addition of streptavidin-peroxidase and tetramethylbenzidine. Samples tested in the 3 Screen were also analysed in ELISAs and radiobinding assays for the three individual autoantibodies. 129/132 (98%) samples from newly diagnosed T1DM children and 1/100 non-diabetic children controls were positive in 3 Screen. There was good agreement between 3 Screen and the individual autoantibody assays. Dilution of positive samples showed good linearity characteristics. In the 2015 Islet Autoantibody Standardization Program 3 Screen achieved 94% sensitivity, 95.6% specificity and 0.948 area under curve by ROC analysis. 3 Screen provides a simple and sensitive method for combined measurement of three major diabetes associated autoantibodies in a single sample. The assay should be a useful tool for large scale population screening for individuals at risk of developing T1DM.