IL-4 induces IL-25 and IL-17 receptor B (IL-17Rb). (A) Human lung slices were incubated with IL-4 (50 ng/ml) for 4 h before immunoblotting for IL-17Rb. (B) Beas-2B cells treated with IL-4 (50 ng/ml) were harvested at the indicated time points and assessed by immunoblotting for signal transducer and activator of transcription 6 (STAT6) phosphorylation at Tyr641 (p-Stat6), IL-17Rb, and IL-25 cytokine. (C) Human alveolar macrophages (alv macs) treated with IL-4 (50 ng/ml) induce expression of IL-17Rb and IL-25 compared to untreated (Untx). (D and E) THP1 cells increase IL-17Rb in response to IL-4 over time (D, 50 ng/ml IL-4) and varying concentrations of IL-4 (E, 4 h exposure). (F and G) IL-17Rb mRNA is induced with IL-4 treatment over 2 h in THP1 cells (F) and in human alveolar macrophages (G) by quantitative PCR. (H) THP cells also produce IL-25 mRNA in response to IL-4. (I) THP1 cells were treated with actinomycin D (Actino) at the indicated concentrations for 30 min before IL-4 (50 ng/ml) and IL-17Rb mRNA was assayed using quantitative PCR. Data are representative of at least three experiments performed on different days. *P < 0.05 and **P < 0.01 by two-sided t test (G and I) or ANOVA (F and H). veh, vehicle.