Nature 415, 1043–1047 (2002).

In this Letter, we characterized a common precursor population for dendritic cells (DCs) isolated from mouse blood by their capacity to generate all DC subpopulations present in mouse lymphoid organs after transfer into irradiated recipients, including CD8- and CD8+ DCs, as well as B220+ plasmacytoid DCs. Phenotypically, they were defined as CD11c+ MHC class II- CD11b+ B220+ CD62L+. However, recent results from our laboratory (C.A., Beatriz León, Verónica Parrillas and G.M.d.H., unpublished work) indicate that, owing to a defect in the isolation method that was used, this common DC precursor population was highly contaminated by circulating NK cells, which express NK1.1 and DX5, display cytolytic activity and are devoid of DC-reconstitution potential when transferred into irradiated mice (C.A., unpublished results). Therefore, the cell population described in our original report comprised CD11c+ B220+ CD62L+ F4/80- DX5+ NK cells and a population of CD11c+ B220- CD62L- F4/80+ DX5- precursor cells with DC differentiation potential. Consequently, as the latter could potentially represent a heterogeneous population containing more than one DC precursor population, the proposed existence of the common DC precursors remains to be established. Experiments are underway to clarify this situation.