Submitted December 22, 2008
Accepted January 22, 2009
Dendritic cell homeostasis
Miriam Merad and Markus G. Manz*
Department of Gene and Cell medicine and Department of Medicine, Mount Sinai School of Medicine, New York, NY, United States
Institute for Research in Biomedicine (IRB), Bellinzona, Switzerland
* Corresponding author; email: manz{at}irb.unisi.ch.
Dendritic cells (DCs) are a heterogeneous fraction of rare hematopoietic cells that co-evolved with the formation of the adaptive immune system. DCs efficiently process and present antigen, move from sites of antigen uptake to sites of cellular interactions, and are critical in the initiation of immune responses as well as in the maintenance of self-tolerance. DCs are distributed throughout the body and are enriched in lymphoid organs and environmental contact sites. Steady-state DC half-lives account for days to up to few weeks and they need to be replaced via proliferating hematopoietic progenitors, monocytes, or tissue resident cells. In this review we integrate recent knowledge on DC progenitors, cytokines and transcription factor usage to an emerging concept of in vivo DC homeostasis in steady-state and inflammatory conditions. We furthermore highlight how knowledge of these maintenance mechanisms might impact on understanding of dendritic cell malignancies as well as post transplant immune reactions and their respective therapies.
