Figure 7.

IL-17A Induces Human Th17 Cells to Produce IL-24, Which Suppresses Expression of Th17-Lineage Cytokines

(A–F) Naive human CD4⁺ T cells were isolated using naive CD4⁺ T cell isolation kit (Miltenyi) and were polarized under Th17 conditions for 14 days. (A) Kinetics of IL-24 expression during Th17 polarization were studied. Cells were collected at the indicated time points and were analyzed using real-time PCR (n = 4). (B) Expression of IL-24 by human Th0 and Th17 cells was determined from supernatant collected by ELISA on day 5 (n = 5). (C, E, and F) Cells were harvested on day 14 and subjected to intracellular staining for the indicated cytokines (C, n = 4; E, n = 5; F, n = 6). (D) Supernatant and cells were harvested on day 5 for ELISA (n = 6) and real-time PCR (n = 8), respectively, to detect IL-24 expression.

^∗p < 0.05, ^∗∗p < 0.01, and ^∗∗∗p < 0.001, paired t test (A, C, and D) and one-way ANOVA (E). (F) Not significant. Data are depicted as mean ± SEM.