IL-29 enhances TLR-induced IL-12p40 production by human monocyte-derived macrophages. (A) Monocyte-derived macrophages were pretreated with IL-29 (100 ng/mL), IFNα (10 ng/mL), or IFNγ (10 ng/mL) for 5 hours, and then further stimulated with LPS or R848. The level of IL-12p40 in the supernatants was determined by ELISA. The values depicted show representative data from 27 independent experiments. The increase of IL-12p40 by IL-29 in monocyte-derived macrophages was observed in 19 of 27 healthy individuals. (B) Monocyte-derived macrophages were pretreated with IL-29, IFNα, or IFNγ at the indicated concentrations for 5 hours, and then further stimulated with R848. The level of IL-12p40 in the supernatants was determined by ELISA. The values depicted show representative data from 3 independent experiments. Medium, IL-29, IFNα, or IFNγ alone did not induce IL-12p40 production by R848-stimulated, monocyte-derived macrophages. (C) Monocyte-derived macrophages were stimulated as described for panel A. The concentrations of IL-12p70, TNF, and IL-10 were determined in the supernatants using ELISA. Macrophages from 10 of 15 healthy individuals showed undetectable levels of IL-12p70 in response to IFNγ and R848 stimulation. (D) Monocyte-derived macrophages were pretreated with IL-29 (100 ng/mL), IFNα (10 ng/mL), or IFNγ (10 ng/mL) for 5 hours, and then further stimulated with LPS or R848. The level of IL-23 in the supernatants was determined by ELISA.