Bcl-2 is a downstream target of IL-15 in NK cells. (A) Left panels show expression of human Bcl-2 transgenic protein (hBcl-2) in gated NK1.1⁺ NK cells from Rag° and Rag°Eμ-2-25 mice. Percentages of Bcl-2⁺ NK cells is indicated. CFSE dilution profiles of splenic NK cells 5 days after adoptive transfer into the indicated hosts. An electronic gate was set on CD122⁺ (IL-2Rβ⁺) cells. (B) Absolute numbers of recovered splenic CD122⁺NK1.1⁺ NK cells at 5 days after transfer. Error bars denote standard deviations. (C) Endogenous Bcl-2 expression is shown in gated NK1.1⁺ splenocytes 4 days after adoptive transfer into the indicated hosts. Control isotype staining (CIg) is indicated by the dark gray histogram.