To further confirm the role of DHX29 in the type I IFN signaling pathway, the effect of DHX29 KD on the expression of type I IFN-stimulated genes and IFN-β production was determined in human and mouse immune cells. Human THP-1 cells, human peripheral blood mononuclear cells (PBMCs), and mouse RAW cells were transfected with DHX29-specific small interfering RNA (siRNA). High efficiency siRNA-mediated KD of DHX29 was observed in all three types of cells (S3A Fig). Compared with the scrambled siRNA control, DHX29 KD markedly reduced IFN-β, IFIT1, IFIT2, and CCL5 mRNA expression and IFN-β production in PBMCs, THP-1 and RAW cells after treatment with LMW Poly(I:C) or HMW Poly(I:C) in lyo/vec form (Vec), but not to Poly(dA:dT) (Fig 2D–2F and S3B–S3E Fig). Taken together, our results suggest that DHX29 plays an important role in type I IFN signaling, and this function is conserved between human and mouse immune cells.