A decrease of CSF IFN-α concentrations, measured with the Simoa pan-IFN-α assay (n = 5), and CSF neopterin (n = 10) upon immunosuppressive treatment was observed in all patients tested, correlating with improvement of SLE and j-NPSLE features (Figs. 1, 2A, and S2). Here, IFNA1 is linked to systemic lupus erythematosus.