Dendritic cells (DCs) present in tissues and circulating blood are originated from bone marrow. Dendritic cells play central roles in innate and adaptive immunity that sense the presence of microbes/ foreign antigens and initiate innate immune response by capturing microbial proteins (antigens), process and presenting to T cells and to initiate foreign antigen specific adaptive immune response.
There are two major subsets of human dendritic cells in human peripheral blood, the plasmacytoid dendritic cells (PDCs) and myeloid dendritic cells (MDCs). MDCs and PDCs are derive from different progenitors and have different functions and have different functions.
Plasmacytoid dendritic cells (PDCs) produce antiviral type I interferons (IFNs) in response to viruses via stimulation of Toll like receptors (TLR-7 and TLR-9). PDCs play an important role in early innate immune response, priming viral T cells and induce host defense to eliminate infectious viruses.