PGE₂-Induced IDO1 Inhibits the Capacity of Fully Mature DCs to Elicit an In Vitro Antileukemic Immune Response

Figure 1

Mature DCs expressed a functionally active IDO1 protein. Human CD14⁺ cells were isolated from healthy donors’ PBMC by using magnetic beads. Immature Mo-DCs were obtained after a 5-day culture in presence of GM-CFS and IL-4. Mature Mo-DCs were obtained following 2 days of incubation with LPS, LPS plus IFN-γ, the cytokine cocktail made of IL-1β, IL-6, and TNF-α, with or without PGE₂. (a) Cells were lysed and RNA was extracted. mRNA expression of IDO1 (normalized to GAPDH) was evaluated by real-time RT-PCR. Universal human RNA was used as reference and taken as value of 1. Data are expressed as the mean ± SEM of 7 independent experiments. , versus immature DCs. (b) DC phenotype was evaluated by flow cytometry. (c) DCs were cultured in presence of 500 μM L-tryptophan for 4 h and supernatants were collected. IDO1 enzymatic activity was evaluated with a spectrophotometric analysis as the production of kynurenine in the supernatants. Data are expressed as the mean ± SEM of 5 independent experiments. , versus immature DCs or versus medium alone.

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