IL-25 inhibits the expression of inflammatory cytokines induced by LPS and PGN in human blood CD14⁺ cells. CD14⁺ cells were isolated from 5 healthy volunteers and preincubated with medium or IL-25 (50 ng/mL) for 30 minutes then either left unstimulated (M = medium) or stimulated with LPS (100 ng/mL) or PGN (10 μg/mL) for a further 6 hours. RNA was extracted and amplified by real-time PCR. Levels are normalized to β-actin and indicate the mean (± SD) of all experiments. LPS/PGN-treated cells versus LPS/PGN + IL-25–treated cells: *P = .02; **P = .04.