A novel cell-based assay for measuring neutralizing autoantibodies against type I interferons in patients with autoimmune polyendocrine syndrome type 1

•A cell based assay for detecting neutralizing antibodies against type I IFN.•The assay is both easy and inexpensive to establish and use.•High correlation with existing assays.•The assay has low intra- and interassay variability.

An important characteristic of autoimmune polyendocrine syndrome type 1 (APS 1) is the existence of neutralizing autoantibodies (nAbs) against the type I interferons (IFN) -α2 and -ω at frequencies close to 100%.Type 1 IFN autoantibodies are detected by antiviral neutralizing assays (AVA), binding assays with radiolabelled antigens (RLBA), enzyme-linked immunosorbent assay (ELISA), or by reporter-based cell assays. We here present a simple and reliable version of the latter utilizing a commercially available cell line (HEK-Blue IFN-α/β).All 67 APS 1 patients were positive for IFN-ω nAbs, while 90% were positive for IFN-α2 nAbs, a 100% and 96% correlation with RLBA, respectively. All blood donors and non-APS 1 patients were negative. The dilution titer required to reduce the effect of IFN-ω nAbs correlated with the RLBA index.This cell-based autoantibody assay (CBAA) is easy to perform, suitable for high throughput, while providing high specificity and sensitivity.