Bcl-2tg NK cells are maintained in IL-15^−/− mice.

CFSE-labeled, enriched NK cells from Bcl-2tg mice (purity about 20%) were adoptively transferred into IL-15^−/−and control mice (n = 2 pairs). At 1.5 days after transfer, the spleen (SP; upper panels) and blood (BL; lower panels) were analyzed for the presence of NK1.1⁺CFSE⁺ NK cells. Cells were gated on viable lymphocytes, and transferred NK cells are highlighted. Similar numbers of Bcl-2tg NK cells were detected in both IL-15^−/− (left) and IL-15^+/− (right) mice. Data from one experiment are shown. Transferred Bcl-2tg NK cells were also detected in similar numbers in IL-15^−/− and control mice 7 days after transfer (data not shown).