LN DN cells develop into NK cells in lymphopenic mice. LN DN1/pre-DN2 cells were purified from IL-15^−/− mice and injected intraperitoneally (10⁴ per mouse) into nonirradiated NOD/Scid/IL-2Rγ^−/− mice. After 3 weeks, lymphocytes from the recipient mice were analyzed by flow cytometry. (A) Donor-derived lymphocytes in the recipients' blood and spleens were identified by anti-CD45.2 and NK cells among donor-derived lymphocytes were detected. (B) The percentages of donor-derived cells in the recipients' blood and spleen (left) and NK cells among donor-derived lymphocytes (right) were determined by flow cytometry. Similar results were obtained with LN DN cells from normal B6 mice. (C) The proliferative capacity (left) of BM NKP cells and LN DN cells was compared by dividing the number of total donor-derived cells in the recipients' spleens by the number of injected cells. The NK-cell potential (right) of BM NKP cells and LN DN cells was also compared by dividing the number of donor-derived NK cells in the recipients' spleen by the number of injected cells. The donor-derived cells in the BM and blood were not included in the calculations as they were much lower than those in the spleen.