Hematopoiesis sculpted by pathogens: Toll-like receptors and inflammatory mediators directly activate stem cells

► Hematopoietic stem cells (HSCs) functionally respond to Toll-like receptor (TLR) ligation. ► TLR ligation of HSCs alters self-renewal and differentiation activities. ► HSCs directly respond to inflammatory cytokines associated with pathogen exposure. ► TLR ligation is associated with human disease and may be therapeutically manipulated.