Although dendritic cells (DCs) and macrophages share a bone marrow origin, these cells
were long assumed to differentiate via discrete pathways. DCs have now been clearly
shown to develop from myeloid lineage precursors, and recent evidence suggests that they
may even differentiate from blood monocytes. Here, J. Hinrich Peters and colleagues assess
current knowledge on the myelomonocytic origin and successive differentiation of human T-
cell-directed DCs.