Fig. 1.

IFN-γ stimulates IDO activity in C-MSC. a Study design for the in vitro experiment to generate C-MSC and IFN-γ-pretreated C-MSC. C-MSCs were cultured with or without various doses of IFN-γ as shown in the schematic figure until the end of the culture period. b Time course study. C-MSCs were exposed to IFN-γ (10 ng/mL) for the indicated time periods. c-e Dose course study. C-MSCs were treated with or without various doses of IFN-γ (10, 50, or 100 ng/mL) for 24 h. b and c The plot shows the ratio of IDO mRNA to GAPDH mRNA. Values represent means ± S.D. of four cultures. d Cell lysates were collected and subjected to immunoblotting for IDO and β-actin expression. e The level of kynurenine in the culture supernatant was measured to monitor IDO activity in C-MSC, as described in the “Methods” section. Values represent means ± S.D. of four cultures. ^* p < 0.05, ^** p < 0.01: values differ significantly (t test). Similar results were obtained from three experiments. GAPDH glyceraldehyde-3-phosphate dehydrogenase, IDO indoleamine 2,3-dioxygenease, IFN interferon