[Plasmacytoid dendritic cells in pathophysiology of immune responses].

Plasmacytoid dendritic cells (pDC), so named because of histological similarities to antibody-producing plasma cells, comprise a unique dendritic cell population. Despite their low numbers in blood they play a key role in anti-viral immunity, mainly through secreting massive amounts of type 1 interferon following an engagement of their Toll-like receptors, such as TLR7 and TLR9, by viral nucleic acids. In a mature state, pDC display a propensity to present antigens to naive lymphocytes. Through their unique potential to rapidly and efficiently secrete type I interferon and serve as antigen presenting cells, pDC are currently considered as one of the major regulators of immune responses.