Fig. 1.

IDO expression by pDCs is induced after Ag-specific interactions with Tregs. (A) IDO mRNA expression in B cells, cDCs, pDCs and macrophages (MØ) sorted from total skin LNs of naïve WT. (B) IDO mRNA in pDCs isolated from total skin LNs of naive WT, Rag2^−/−, OTII Rag2^−/− and IDO^−/− mice. (C) CD5 expression levels by AND Rag2^−/−, Smarta Rag1^−/− (SMA) and Marilyn Rag2^−/− (MAR) CD4⁺ TCR tg T cells (left), and IDO mRNA levels in pDCs isolated from skin LN of AND, SMA, MAR and WT mice (right). (C) Foxp3⁺CD4⁺ Treg frequencies in LNs of OTII Rag2^−/− and female Marilyn Rag2^−/− mice. (E) Foxp3⁺CD4⁺ Treg frequencies in LN cells of 2D2 TCR tg mice (left), and IDO mRNA levels in pDCs isolated from skin LN of Rag2^−/− mice and co-cultured in vitro with 2D2 TCR tg CD4⁺ T cells and MOG_35–55 peptide for 16 h (right). (F) IDO mRNA levels in ex-vivo pDCs sorted from skin LN of 3wk-old WT, pIII + IV^−/− and Scurfy mice. (G) IDO mRNA levels of ex vivo WT pDCs and WT BM derived pDCs loaded or not with MOG_35–55 and co-cultured in vitro with 2D2 CD4⁺ T cells for 16 h. (H) IDO mRNA levels of ex vivo WT pDCs and WT BM derived pDCs loaded with MOG_35–55 and co-cultured in vitro for 16 h with 2D2 CD4⁺ CD25⁻ cells, 2D2 CD4⁺ T cells or 2D2 CD4⁺ CD25⁺ Treg cells. (A–H) Results are representative of at least 2 independent experiments. Error bars depict mean ± SEM. (A, B, C, G, and H) One-way ANOVA with Bonferroni post Hoc test or (E and F) two-tailed Mann-Whitney test was used. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001, NS = Non significant.