Indoleamine 2,3-dioxygenase–expressing dendritic cells form suppurative granulomas following Listeria monocytogenes infection
J. Clin. Invest. Alexey Popov, et al. 116:3160 doi:10.1172/JCI28996 [Go to this article.]

Figure 3
IDO is expressed on transcriptional and functional levels in human DCs infected with L. monocytogenes. (A) Time kinetic of IDO mRNA expression was assessed by quantitative real-time PCR. Expression of β-2 microglobulin (B2M) was used as a housekeeping gene control. Shown here are IDO expression profiles (normalized to B2M expression) in DC cultures derived from 3 different donors. Samples after L. monocytogenes infection are represented by filled symbols, the corresponding control samples by open symbols. (B) Protein expression of IDO and β-actin was assessed by immunoblotting after L. monocytogenes infection. Results of 1 representative experiment out of 6 are shown. rhIDO was used as a positive control. (C) Tryptophan depletion by enzymatically active IDO in cell supernatants was assessed by reverse-phase HPLC. Shown here is the reduction of tryptophan after 6, 12, or 24 hours in DC culture supernatants relative to tryptophan concentrations measured in DC medium alone. Mean ± SD of 3 independent experiments is shown. Asterisks highlight statistically significant comparisons (*P < 0.05, **P < 0.00001). (D) Kynurenine accumulation at the same time points was assessed using a photometric assay. Shown here are mean ± SD of 3 independent experiments. Asterisks highlight statistically significant comparison (***P < 0.01). (E) Macrophages (Mf) and DCs were differentiated from monocytes and infected with wild-type L. monocytogenes. After 24 hours, IDO protein expression was assessed by immunoblotting and analyzed quantitatively respective to β-actin expression. Representative Western blot and mean ± SD of 3 independent experiments are shown. Asterisks highlight statistically significant comparison (***P < 0.01).