Fig 5.

NH₄⁺ reduces IL-10 secretion by LPS-stimulated moDC. Immature moDC were prepared and stimulated with LPS as described in the legend to Fig. 4 in medium supplemented with either arginine alone (control) or arginine plus NH₄⁺Cl. After 24 h, supernatants were taken and cytokine concentrations were determined by ELISA. Cytokine concentrations are expressed as percent differences from the cytokine amounts produced by control cells. Each dot represents an independent experiment with moDC prepared from an individual donor. Significance was tested against the null hypothesis that addition of NH₄⁺ had no effect by paired (two-tailed) t test. P values were significant (P < 0.01) for IL-10 levels and nonsignificant (P > 0.05) for TNF-α levels.