Cytokine quantification.

Plasma IL-18 and CXCL9 were measured by ELISA as previously described (15). Plasma IL-15 was quantified by proximity extension assay through Olink. Bioactivity of IFN-I in human plasma was measured using a luciferase reporter cell line as described (67). HEK 293T cells with luciferase expression under the control of IFN-sensitive response element were maintained in DMEM supplemented with penicillin / streptomycin and 10% FBS. Cells (1 × 10⁵ per well) were plated in a 96-well plate and cultured in 200 μL of complete medium with 10% human plasma (from healthy controls or patients) for 18 hours. Duplicate wells were tested for each plasma sample. Cell lysate preparation and quantification of luciferase activity were performed using the BrightGlo reagent (Promega) according to manufacturer’s instructions.