Effect of recombinant interleukin 27 on interleukin 17 production and type 17 T helper cell differentiation in Behçet’s disease patients and healthy controls. Naïve CD4+ T cells from patients with active Behçet’s disease (BD) (n = 8), patients with inactive BD (n = 8) and healthy controls (n = 8) were stimulated with or without recombinant interleukin 27 (rIL-27) (100 ng/ml) under type 17 T helper cell (Th17) polarizing conditions for 6 days. (A) and (B) IL-17 production in the culture supernatants of stimulated naïve CD4+ T cells was measured by enzyme-linked immunosorbent assay. (C) Intracellular staining of IL-17 was investigated by flow cytometric analysis. Representative flow cytometry plots for each group are shown. (D) and (E) Quantitative analysis of the percentage of IL-17-producing CD4+ T cells was carried out by paired-samples t-test for related samples and one-way analysis of variance for independent samples. All data are representative of five independent experiments and are expressed as average ± standard deviation.