Role of plasmacytoid dendritic cells in immunity and tolerance after allogeneic hematopoietic stem cell transplantation.

Dendritic cells (DC) may play an important role in the pathogenesis of alloimmune reactions, such as graft-vs.-host disease after allogeneic hematopoietic stem cell transplantation (HSCT). In humans, two types of DC-myeloid DC (mDC) and plasmacytoid DC (pDC) have been characterized and have distinct origins and functions. The data obtained from studies in vitro suggest that pDC are involved in the regulation of immunity, including the induction and maintenance of tolerance, as well as in the defence against viruses. The authors will review all the evidence currently available from reports exploring the role of pDC in clinical allogeneic HSCT.