Plasmacytoid dendritic cell

Plasma cytoid dendritic cells belong to the professional antigen-presenting cells. They are found in small numbers in peripheral blood and the peripheral lymphatic system. PDCs account for less than 0.4% of peripheral blood mononuclear cells (PBMC). In the dormant, non-activated stage, PDCs already stand out morphologically from typical dendritic cells, e.g. Langerhans cells, due to the absence of dendritic spurs.

Plasma cytoid dendritic cells (pDCs) are similar to plasma cells but are not involved in antibody production or secretion. They lack the typical myeloid marker molecules CD11b, CD11c, CD13, CD33. Instead they express CD45RA, CD123, CD303 and CD304. Among professional antigen-presenting cells, plasma cytoid dendritic cells (pDC) are the main producers of the type 1 interferons IFN alpha and IFN beta. They thus play an important role in the initial immune response against infectious agents and tumors.

Plasmacytoid dendritic cells express the toll-like receptors TLR-7 and TLR-9, which enable pDCs to recognize viral and microbial DNA and activate them with consecutive production of type 1 interferons. When activated, PDCs can express dendritic offshoots.

A very rare, highly aggressive lymphatic systemic disease, which originates from precursors of plasmacytoid dendritic cells, is the blast plasmacytoid dendritic cell neoplasia. Cases of this lymphatic systemic disease have been reported after acute myeloid leukemia (AML).

1. Chang HJ et al (2012) A case of blastic plasmacytoid dendritic cell neoplasm initially mimicking cutaneous lupus erythematosus. Med Oncol 29:2417-2422
2. Cota C et al (2010) Cutaneous manifestations of blastic plasmacytoid dendritic cell neoplasm-morphologic and phenotypic variability in a series of 33 patients. Am J Surg Pathol 34: 75-87
3. Shortman K et al (2013) Plasmacytoid dendritic cell development. Adv Immunol 120:105-126.