Mice lacking the ligand for Flt-3 (CD135) have a massive deficit of dendritic cells (DC) in all organs. This phenotype of FL (FL) knockout mice suggested that FL was the archetypal DC poietin in the steady state. However, FL knockout mice also have reduced numbers of common lymphoid progenitors (CLP) and common myeloid progenitors (CMP) so it is possible that FL deficiency may limit the ability of other growth factors to drive DC development by limiting the pool of progenitor cells available. We found that DC development could be driven from BM cells of FL knockout mice using the myeloid growth factor M-CSF. The M-CSF-driven DC (MDC) developed independently of FL and resembled the DC types present in the spleen in the steady state.
