Dendritic Cells: Location, Function, and Clinical Implications

Abstract

Dendritic cells (DCs) are antigen-presenting cells derived from bone marrow precur- sors and form a widely distributed cellular system throughout the body. DCs exert immune-surveillance for exogenous and endogenous antigens and the later activa- tion of naive T lymphocytes giving rise to various immunological responses. Different growth factors and cytokines can modulate the differentiation and function of DCs, GM-CSF, M-CSF, Flt3, and TGF-β, resulting in a large variety of DCs with different functional abilities. Thus, DCs are classified as plasmacytoid DCs (pDCs), conven- tional DCs (cDCs), and DCs derived from monocytes (mDCs). Functionally, the cDCs may be divided into two states: immature and mature. Immature DCs are specialist in uptaking and processing antigens; in contrast, mature DCs are professional in antigen presentation. It has been observed that immature cDCs can induce immune tolerance while mature cDCs may induce Th2 or Th1 immune responses. It is worth noting that different subpopulations of DCs have the ability to secrete different cytokine patterns, resulting in the induction of different immunological responses. Furthermore DCs are involved in the pathophysiology of several diseases such as contact hypersensitivity, autoimmune diseases, or cancer, but they can also be used as therapeutic tools in these conditions.