mTOR Signaling and Dendritic Cell Biology

Dendritic cells (DCs) are a heterogeneous population of antigen-presenting cells (APCs) specialized to capture, process, and present antigens to T lymphocytes [1]. DCs develop from bone marrow (BM)-derived precursor populations, including monocyte and dendritic cell progenitors (MDPs) and common DC progenitors (CDPs) that subsequently give rise to plasmacytoid DCs (pDCs) and conventional DCs (cDCs). In the peripheral tissues, DCs encountering pathogens undergo maturational event through upregulation of co-stimulatory molecules (such as CD40, CD80 and CD86) and alteration of adhesion molecules. Antigen-bearing DCs then migrate to T cell areas of secondary lymphoid tissues, where they provide antigenic, co-stimulatory and cytokine signals to naïve T cells to initiate effector immune responses. In the absence of inflammatory or infectious signals, DCs present self-antigens in secondary lymphoid tissues to induce and maintain self-tolerance. Therefore, by bridging innate and adaptive immunity, DCs play a central role in orchestrating the decision between immunity and tolerance.