Probing in vivo origins of mononuclear phagocytes by conditional ablation and reconstitution

Dendritic cells (DCs) and macrophages (MΦs), collectively termed mononuclear phagocytes (MP), are crucial for homeostatic tissue maintenance as well as the innate and adaptive host defense. These pleiotropic functions are likely to be covered by distinct DC and MΦ subsets, defined by anatomic location and molecular make-up. However, task division within the MP system remains poorly defined. A key to understanding of this issue, which might have important implications for the development of future therapeutic strategies, is the elucidation of the in vivo origins of DCs and MΦs, whose study recently gained striking momentum. Here we present methods to investigate the role of MP progenitors, such as monocytes and MΦ/DC precursors (MDPs), in the replenishment of the peripheral MP system.