Microarray analysis of gene expression in^HGFMo. Monocytes were isolated from the peripheral blood of 3 different healthy donors as detailed in “Materials and methods” and were used in 3 independent experiments, each performed in triplicate. (A) Eisen tree map of the 672 genes that showed significant differences in their expression levels was performed using a supervised approach (ANOVA), as detailed in “Materials and methods.” A combination of 2 hierarchic clustering analyses, the “gene tree” on the left and the “condition tree” on top, is shown. Gene coloring was based on normalized signals, as indicated at the bottom of the panel. (B) Eisen tree map computed using the Pearson correlation equation on the 29 modulated probe sets passing the Tukey post-hoc test. Gene coloring was based on normalized signals, as indicated at the bottom of the panel. Detection of IDO protein expression in GM4-DCs and ^HGFMo by immunocytochemistry (C) and Western blot (D). One representative experiment out of 3 with similar results is shown. Cells were visualized using an AX70 digital microscope (Olympus) equipped with a 40 ×/0.65 NA objective lens. Image acquisition was performed as described for Figure 2A. (E) Effect of IDO inhibition on the proliferation of CD4⁺ T cells in primary MLR cultures. 1-methyl-D-tryptophan (1-MT; Sigma Chemical) was added at the beginning of the MLR at 200 μM (final concentration).⁶⁴  CFSE-labeled CD4⁺ T cells were cultured in the presence of either GM4-DCs, ^HGFMo, or cytokine-untreated monocytes that were cryopreserved at the start of the experiment (stimulator-to-responder cell ratio equal to 1:3). T-cell proliferation was expressed in terms of PI, as previously detailed. One representative experiment of 3 with similar results is shown. Error bars indicate mean and SD. ^*P < .01 compared with MLR cultures performed in the absence of 1-MT.