IFN-I can be induced by hemolysis. (A) Fold change in 14 IFN-I inducible genes as determined by RNA-Seq (IFI44, IFI44L, Mx1, Mx2, LY6E, EPSTI1, RSAD2, IFI6, OAS3, IFIT1, IFIT3, HERC5, ISG15, and SIGLEC1) in SCD CMo (n = 13) relative to HD CMo (n = 6). (B) Plasma IFN-α levels in HD (n = 19) and SCD patients at steady state on a chronic transfusion protocol (n = 36). (C) Plasma IFN-α levels in control and sickle mice (n = 5-6). (D) Scatter plot analysis showing correlation relationship between plasma IFN-α levels and plasma total heme levels in patients with SCD (n = 36 as in panel B). (E) Plasma IFN-α levels in WT mice at 20 hours after IV injection with PBS as control (200 µL/20 g body weight), water (300 µL/20 g body weight), RBC lysate (17.5 µmol hemoglobin/kg body weight in 200 µL), hemoglobin (17.5 µmol/kg body weight in 200 µL), or hemin (17.5 µmol/kg body weight in 200 µL) (n = 4-8). (F) Plasma IFN-β levels in WT mice at 20 hours after IV injection with PBS as control (200 µL/20 g body weight), or hemin (35 µmol/kg body weight in 200 µL) (n = 3-5). (G) Plasma IFN-α levels in WT mice at 20 hours after IV injection with hemin at doses of 0, 4.4, 8.8, 17.5, or 35 µmol/kg body weight all in 200 µL (n = 3-10). (H) Plasma IFN-α levels in WT mice at time point of 0, 2, 6, 20, and 72 hours after IV injection with hemin (35 µmol/kg body weight in 200 µL) (n = 3-7). Data represent mean ± SEM; means were compared using 2-tailed Student t test. *P < .05.