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Bone Marrow Research
Volume 2012, Article ID 165107, 8 pages
http://dx.doi.org/10.1155/2012/165107
Review Article

Hematopoietic Stem and Progenitor Cells as Effectors in Innate Immunity

1Department of Pathology, Microbiology, Immunology, University of California School of Veterinary Medicine, Davis, CA 95616, USA
2Department of Biomedical Engineering, University of California, Davis, CA 95616, USA

Received 11 February 2012; Revised 22 April 2012; Accepted 28 April 2012

Academic Editor: Meenal Mehrotra

Copyright © 2012 Jennifer L. Granick et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Recent research has shed light on novel functions of hematopoietic stem and progenitor cells (HSPC). While they are critical for maintenance and replenishment of blood cells in the bone marrow, these cells are not limited to the bone marrow compartment and function beyond their role in hematopoiesis. HSPC can leave bone marrow and circulate in peripheral blood and lymph, a process often manipulated therapeutically for the purpose of transplantation. Additionally, these cells preferentially home to extramedullary sites of inflammation where they can differentiate to more mature effector cells. HSPC are susceptible to various pathogens, though they may participate in the innate immune response without being directly infected. They express pattern recognition receptors for detection of endogenous and exogenous danger-associated molecular patterns and respond not only by the formation of daughter cells but can themselves secrete powerful cytokines. This paper summarizes the functional and phenotypic characterization of HSPC, their niche within and outside of the bone marrow, and what is known regarding their role in the innate immune response.