Endogenous PGE₂ and IL-23 affect the production of IL-17 by human PBMCs. Culture conditions as in the legend of Figure 1. Indomethacin (10⁻⁵ M) and anti–IL-23 mAb (10 μg/mL) were added at the beginning of the culture. Cytokines were assessed by multiplex immunoassay. Bars represent the mean percentage plus or minus SD of the response of the nil culture condition of 9 distinct individual donors. In the nil culture condition, IL-17 was 198.9 (± 182.4) ng/mL, IFN-γ was 1693.9 (± 1365.5) ng/mL, and IL-1β was 617.0 (± 257.2) ng/mL. *Significant differences (P < .01) compared with nil by paired Student t test.