Type I IFN induction by DNA-LL37 complexes in human monocytes occurs through cytosolic DNA sensors. (A) IFN-α produced by pDCs and monocytes after overnight stimulation with 10 μg/mL of poly dA:dT or poly dC:dG DNA, either alone or in complex with LL37 (10μM), with or without pretreatment with 50nM bafilomycin. Data are representative of at least 5 independent experiments; error bars represent the SD of triplicate wells. *P < .0001 (paired Student t test). (B) Real-time PCR of TBK1, MyD88, and STING expression after transfection with siRNA targeting TBK1, MyD88, STING, or control nontargeting RNAi sequences (control siRNA [C RNAi]) in primary human monocytes. Data are representative of at least 3 independent experi-ments; error bars represent the SD of triplicate wells. *P < .01 (paired Student t test). (C) Real-time PCR of Ifna mRNA induction in primary human monocytes stimulated with huDNA-LL37 complexes 48 hours after transfection with siRNAs targeting TBK1, MyD88, or control nonsilencing siRNAs. Data are representative of at least 4 independent experiments for TBK1 and MyD88 silencing and 2 independent experiments for STING silencing; error bars represent the SD of triplicate wells. *P < .01 (paired Student t test). (D) ELISA of IFN-α in human monocytes after stimulation with poly dC:dG DNA (B-type DNA) in complex with LL37 complexes or brominated poly dC:dG DNA (Z-type DNA)-LL37. Data are representative of at least 3 independent experiments; error bars represent the SD of triplicate wells. *P < .0001 (paired Student t test).