Emergency Evacuation! Hematopoietic Niches Induce Cell Exit in Infection

The roles of hematopoietic stem and/or progenitor cell niches during infection remain unclear. In this issue of Immunity, Shi et al. (2011) reveal that these niches upregulate MCP1 chemokine expression, inducing emigration of bone marrow monocytes into the circulation via the endothelium