Submitted April 26, 2007
Accepted January 17, 2008
Unique subset of natural killer cells develops from progenitors in lymph node
Linnea Lora Veinotte, Timotheus You Fu Halim, and Fumio Takei*
Terry Fox Laboratory, British Columbia Cancer Agency, and Department of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, B.C., Canada
* Corresponding author; email: ftakei{at}bccrc.ca.
Natural killer (NK) cells have been thought to develop from committed progenitors in the bone marrow. However, a novel pathway of thymus-dependent NK cell development that produces a unique subset of NK cells expressing CD127 has recently been reported. We now have identified two populations of NK progenitors, one in the thymus and the other in the lymph node (LN). Immature double negative 2 (CD4-CD8-CD44+CD25+) thymocytes have potential to produce NK cells with rearranged T cell receptor gamma genes (Tcr
+) in vitro. Tcr+ NK cells are rare in spleen but relatively abundant in the thymus and LN. About 20% of LN NK cells are Tcr+, and they are found at similar levels in both CD127+ and CD127- subsets. Moreover, a subpopulation of LN cells resembling immature thymocytes differentiates into Tcr+ NK cells in vitro and also repopulates the NK compartment in lymphopoenic mice. Athymic mice lack the LN NK progenitors expressing CD127 as well as Tcr+ NK cells. These results suggest that Tcr+ NK cells may be generated from unique progenitors in the thymus as well as in the LN.
