Effects of blocking IL-10, IL-4, NO, or prostaglandins on LPS-induced IL-12p70 and IL-12p40 downregulation. Monocytes were incubated with LPS (50 ng/mL) or with LPS and neutralizing anti–IL-10 antibody (10 μg/mL), anti–IL-4 antibody (10 μg/mL), indomethacin (1 × 10⁻⁶ mol/L) or NMLA (10 μmol/L) for 24 hours. Supernatants were removed and cells in fresh medium were stimulated with IFN-γ (300 U/mL) and LPS (50 ng/mL) for another 24 hours. The mean values of p70 and p40 levels in the supernatants of at least 3 separate experiments are shown. Bars indicate SEM.