Despite years of research, the identity of the bone marrow progenitor cells that seed the thymus, as well as the place where they ultimately commit to being T cells, have remained elusive. On page 21, Benz and Bleul identify the first multipotent progenitor cell in the adult thymus. The new data suggest that, for at least some progenitor cells, commitment to a T cell fate occurs after arrival in the thymus.
Populations of thymic precursor cells have been shown to generate multiple cell lineages, but it remains a matter of debate whether single precursor cells can give rise to all the possible thymic cell lineages—T cells, B cells, and dendritic cells (DCs).
Benz and Bleul now show that these cell types can indeed arise from a single precursor cell. By fusing EGFP with a marker of T cell development sites (CCR9), they pinpointed a...
