Flt3L from interfollicular stroma maintains resident dendritic cells.

Dendritic cell (DC) maintenance and positioning are essential for their function in lymph nodes. Wu et al. identify gremlin1 (Grem1)+ fibroblastic reticular cells as critical source of niche-specific Fms-like tyrosine kinase 3 ligand (Flt3L) for conventional DC maintenance in health and disease, highlighting stromal cells as key regulators of immunity.