Monocyte-derived DCs retain the expression of functional IDO and CD25 after removal of PGE2 and maturation signals. (A) IDO protein expression and enzymatic activity as measured by tryptophan levels 24 hours after washout (6 independent experiments). Black bars represent PGE2-treated DCs; mean ± standard deviation of all experiments is shown. ^*P < .05. (B) Surface expression of CD25 on mature DCs before and 24 hours after washout. One representative experiment of 4 is shown. (C) Production of soluble CD25 as determined by ELISA from supernatants after washout. Shown here is the mean ± SD of 6 independent experiments. Black bars represent PGE2-treated DCs; mean ± standard deviation of all experiments is shown. ^*P < .05.