A chemokine system in CD8 positive dendritic cells.

Abstract

Dendritic cells (DC) are specialized antigen presenting cells that play critical roles to link innate and adaptive immunity. DCs are highly heterogeneous populations and can be divided into several subsets according to their physiological functions and expression patterns of cell surface molecules. We have found that XC chemokine receptor 1 (Xcr1) is exclusively expressed in one DC subset, CD8α⁺ DCs which have abilities to uptake apoptotic cells and cross-present soluble/cells-associated antigens on MHC class I to cytotoxic CD8 T cells. Xcr1-expressing DCs showed chemotactic migration to an Xcr1 ligand, Xcl1. We also showed that Xcl1 was constitutively expressed by NK cells and its expression was enhanced upon IL-2 stimulation. Furthermore, Xcl1 was also induced in CD8, but not CD4, T cells after crosslinking of anti-CD3ε plus anti-CD28 antibody, suggesting that a CD8α⁺ DC subset might migrate to NK cells or activated CD8 T cells via Xcr1 during immune responses.