Neutralizing autoantibodies against type I IFNs. (A) Luciferase-based neutralization assay to detect auto-Abs neutralizing 10 ng/ml IFNα2, IFN-ω, or IFN-β in an individual previously known to have neutralizing anti-IFN-I auto-Abs (C+), healthy donors (HD), and the patient, and the patient with the variants in CHUK (P). (B) Luciferase-based neutralization assay to detect auto-Abs neutralizing 100 pg/ml IFNα2, IFN-ω in an individual previously known to have neutralizing anti-IFN-I auto-Abs (C+), healthy donors (HD), and the patient with the variants in CHUK (P). Relative luciferase unit (RLU) is calculated by normalizing Firefly luciferase activity against the Renilla luciferase activity, before normalization against non-stimulated conditions. An induction factor of >5 relative to non-stimulated conditions was considered to correspond to neutralizing activity (dashed line). These experiments have been performed twice.