Dendritic Cells and their Markers

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Overview

Dendritic cells (DCs) are a functionally, developmentally and phenotypically diverse group of cells. In addition to being potent stimulators/activators of an adaptive immune response DCs can also initiate an innate immune response and even have a role in immune tolerance (Schraml & Sousa 2015). DCs have been found to be involved in two types of immune suppression; either “central tolerance” where self-reactive T cells, direct from the thymus, are eliminated or “peripheral tolerance” where harmful antigens in the tissue are removed (Chung et al. 2013).

Classical DCs (cDCs) and pre-plasmacytoid DCs (pDCs) are derived from the common lymphoid progenitor (CLP) and common myeloid (CMP) pathways that originate in bone marrow and terminate as blood borne monocytes that develop into mature DCs. The precise point at which the development of the long lasting pDCs and the shorter lasting, high turnover, cDCs diverge remains a point of debate. More recent evidence has indicated that development may involve a common DC precursor from which cDCs are developed and a pre-plasmacytoid DCs which differentiate into plasmacytoid DCs (pDCs) (Reizis et al. 2011, Schraml & Sousa 2015).

cDCs are highly migratory and are found at sites of likely microbial encounters such as the gut, skin and lungs. The immature cDCs capture and process antigen then transit from these tissues to lymphoid organs such as spleen and lymph nodes where they mature, up-regulate co-stimulatory molecules and present the antigen in the context of a MHC-II-peptide complex to lymphocytes (Geissmann et al. 2010).

pDCs are also found in peripheral organs, primarily those of the lymphatic system in a steady state (Geissmann et al. 2010). The fundamental function of pDCs is to respond to viral infection, by the secretion of type I interferon alpha/beta; however they can also be involved in both the activation and control of T cell responses (Geissmann et al. 2010).

Dendritic Cells markers

To date, no single cell marker has been found to be expressed exclusively on DCs, therefore a combination of the presence and absence of various cell markers can be used to identify the DCs. The table below lists key markers that can be used in the identification of DCs alongside the absence of lineage markers, such as CD3 (T cell), CD14 (monocyte), CD19 (B cell), CD56 (NK cell) and CD66b (granulocyte).

Key dendritic cells markers:

Table constructed using data from Geissmann et al. 2010, Reizis et al. 2011, Merad et al. 2013 and Schraml & Sousa 2015.

References

• Geissmann F et al. (2010). Development of monocytes, macrophages and dendritic cells.
  Science. 327(5966):656-661.
• Reizis B et al. (2011). Plasmacytoid Dendritic Cells: Recent Progress and Open Questions.
  Annu Rev Immunol. 29:163-183.
• Chung CY et al. (2013). Dendritic Cells: Cellular Mediators for Immunological Tolerance.
  Clin Dev Immunol. 2013:972865.
• Merad M et al. (2013). The Dendritic Cell Lineage: Ontogeny and Function of Dendritic Cells and Their Subsets in the Steady State and the Inflamed Setting.
  Annu Rev Immunol. 31: 563-604.
• Schraml BU & Sousa CR. (2015). Defining dendritic cells.
  Curr Opin Immunol. 32:13-20.