Potential Regulatory Function of Human Dendritic Cells Expressing Indoleamine 2,3-Dioxygenase

TLDR

Antigen‑presenting cells can induce tolerance or immunity. The study describes a subset of human APCs that express indoleamine 2,3‑dioxygenase and inhibit T‑cell proliferation in vitro. IDO‑positive APCs were identified by co‑expression of CD123 and CCR6 and displayed suppressor activity in both mature and immature CD123+ dendritic cells. IDO+ dendritic cells were also detected in vivo, indicating a potential regulatory subset of APCs in humans.

Abstract

Antigen-presenting cells (APCs) can induce tolerance or immunity. We describe a subset of human APCs that express indoleamine 2,3-dioxygenase (IDO) and inhibit T cell proliferation in vitro. IDO-positive APCs constituted a discrete subset identified by coexpression of the cell-surface markers CD123 and CCR6. In the dendritic cell (DC) lineage, IDO-mediated suppressor activity was present in fully mature as well as immature CD123+ DCs. IDO+ DCs could also be readily detected in vivo, which suggests that these cells may represent a regulatory subset of APCs in humans.