| First Author | Fallarino F | Year | 2005 |
| Journal | Int Immunol | Volume | 17 |
| Issue | 11 | Pages | 1429-38 |
| PubMed ID | 16172135 | Mgi Jnum | J:102311 |
| Mgi Id | MGI:3607353 | Doi | 10.1093/intimm/dxh321 |
| Citation | Fallarino F, et al. (2005) Ligand and cytokine dependence of the immunosuppressive pathway of tryptophan catabolism in plasmacytoid dendritic cells. Int Immunol 17(11):1429-38 |
| abstractText | Murine plasmacytoid dendritic cells (pDCs) have been credited with a unique ability to express indoleamine 2,3-dioxygenase (IDO) function and mediate immunosuppression in specific settings; yet, the conditions of spontaneous versus induced activity have remained unclear. We have used maneuvers known to up-regulate IDO in different cell types and have examined the relative efficacy and mechanisms of the induced activity in splenic pDCs, namely, after specific receptor engagement by CTLA-4-Ig, CD200-Ig or CD28-Ig, the latter in combination with silenced expression of the suppressor of cytokine signaling 3 (SOCS3) gene. We found that pDCs (CD11c(+) mPDCA-1(+) 120G8(+)) do not express IDO and are not tolerogenic under basal conditions. B7-1 engagement by CTLA-4-Ig, CD200R1 engagement by CD200-Ig and B7-1/B7-2 engagement by CD28-Ig in SOCS3-deficient pDCs were each capable of initiating IDO-dependent tolerance via different mechanisms. IFN-gamma was the major cytokine responsible for CTLA-4-Ig effects, and type I IFNs for those of CD200-Ig. Immunosuppression by CD28-Ig in the absence of SOCS3 required IFN-gamma induction and IFN-like actions of IL-6. Therefore, although pDCs do not mediate IDO-dependent tolerance constitutively, multiple ligands and cytokines will contribute to the expression of a tolerogenic phenotype by pDCs in the mouse. |
