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.
Myeloid dendrtic cells (MDCs) have some capacity to produce IL-12 and thereby to induce Th1 development.