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.

Plasmacytoid dendritic cells (pDCs) resemble 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. Plasmacytoid dendritic cells (pDC) are the main producers of the type 1 interferons IFN alpha and IFN beta among the professional antigen-presenting cells. They therefore play an important role in the initial immune response against infectious agents, tumors and autoimmune diseases(lupus erythematosus).

The BDCA2 protein plays an important role. This is expressed exclusively on plasmacytoid dendritic cells (pDCs), whose uncontrolled production of type I IFN (IFN-I) is crucial for the pathogenesis of SLE and other autoimmune diseases. Recently, an anti-BDCA2 antibody has been developed that causes a complete suppression of IFNα production and a broader inhibition of inflammatory cytokine production (Li X et al. 2024).

Plasmacytoid dendritic cells express the Toll-like receptors TLR-7 and TLR-9. pDCs can recognize viral and microbial DNA via these Toll-like receptors, whereupon they are activated with consecutive production of type 1 interferons. When activated, PDCs can express dendritic progenitors.

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

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. Li X et al. (2024) An immunomodulatory antibody-drug conjugate targeting BDCA2 strongly suppresses plasmacytoid dendritic cell function and glucocorticoid responsive genes. Rheumatology (Oxford) 63:242-250.

4. Shortman K et al. (2013) Plasmacytoid dendritic cell development. Adv Immunol 120:105-126.