Hematopoietic stem and progenitor cells and the inflammatory response.

Cells of the vertebrate immune system are continuously regenerated by division of hematopoietic stem cells (HSCs) into differentiated effector cells. Classically, HSCs were thought to reside primarily in the bone marrow niche where they produced mature progeny that migrated from the marrow to repopulate the peripheral immune system. However, emerging evidence has established that hematopoietic stem and progenitor cells (HSPCs) are themselves mobile and able to repopulate ectopic niches and contribute more directly to inflammatory responses in the periphery. How the HSPCs remain immune to destruction in a toxic inflammatory milieu is unknown.