• dendritic cells;
  • development;
  • T cell;
  • antigen presentation;
  • immunity;
  • tolerance

Summary:  Mouse lymphoid tissues contain a subset of dendritic cells (DCs) expressing CD8α together with a pattern of other surface molecules that distinguishes them from other DCs. These molecules include particular Toll-like receptor and C-type lectin pattern recognition receptors. A similar DC subset, although lacking CD8 expression, exists in humans. The mouse CD8+ DCs are non-migrating resident DCs derived from a precursor, distinct from monocytes, that continuously seeds the lymphoid organs from bone marrow. They differ in several key functions from their CD8 DC neighbors. They efficiently cross-present exogenous cell-bound and soluble antigens on major histocompatibility complex class I. On activation, they are major producers of interleukin-12 and stimulate inflammatory responses. In steady state, they have immune regulatory properties and help maintain tolerance to self-tissues. During infection with intracellular pathogens, they become major presenters of pathogen antigens, promoting CD8+ T-cell responses to the invading pathogens. Targeting vaccine antigens to the CD8+ DCs has proved an effective way to induce cytotoxic T lymphocytes and antibody responses.