Figure 2. Inhibition of indoleamine 2,3-dioxygenase enzyme activity by different inhibitors.

(A) Determination of the kynurenine production in HFF cells after IDO induction by IFN-γ (100 U/mL). The cells were incubated for 72 h under normoxia (20% O₂) or hypoxia (1% O₂) and treated with different amounts of the JAK2 inhibitor BSK805 (0–2 µM). (B) Kynurenine production of HFF cells after IDO induction by IFN-γ (100 U/mL). The cells have been incubated for 72 h under normoxia (20% O₂) or hypoxia (1% O₂) with different amounts of the proteasome inhibitor MG-132 (0–1 µM) or the sumoylation inhibitors Anancardic Acid (0–10 µM) or Ginkgolic Acid (0–10 µM). The kynurenine content in the cell culture supernatants was determined by optical density at 492 nm +/− SEM, using Ehrlichs reagent. A significant inhibition of kynurenine production as compared to the stimulated normoxia positive control is marked with asterisks. In B the addition of inhibitors did not result in a significant increase of the kynurenine production in cells incubated under hypoxia, this is marked by n.s. (not significant), n = 3.