IL-29 enhances, but IFNα suppresses, IFNγ-induced IL-12p40 production by human monocyte-derived macrophages in response to R848 stimulation. (A-B) Monocyte-derived macrophages were pretreated with IL-29 or IFNα for 5 hours, and then further stimulated with IFNγ in combination with R848. IL-12p40, TNF, and IL-23 production were determined by ELISA. The values depicted show representative data from 7 independent experiments. (C) Monocyte-derived macrophages were pretreated with IL-29 or IFNα for 5 hours, and then further stimulated with IFNγ in combination with R848 for another 5 hours. IL-12p40, IL-12p35, and IL-23p19 mRNA expression in macrophages was quantified by RT-PCR. The values depicted show representative data from 2 independent experiments.