Functional immaturity of Tg NK cells. (A) Freshly isolated BM cells from WT and Tg mice pretreated with poly-I:C were used in standard cytotoxicity assays against the indicated targets. (B) BM and spleen cells were stimulated with IL-2 plus IL-12 and analyzed for intracellular IFNγ. Gated NK1.1⁺ CD3^- cells are shown, and the numbers represent the percentages of IFNγ-producing cells. (C) Spleen cells from indicated mice were co-incubated with YAC-1 tumor cells and analyzed for intracellular IFNγ. Gated NK1.1⁺ CD3^- cells are shown, and the numbers represent the percentages of IFNγ-producing cells. (D) Splenocytes from indicated mice were stimulated by anti-NK1.1 cross-linking then analyzed for intracellular IFNγ. Gated NK1.1⁺ CD3^- cells are shown, and the numbers represent the percentages of IFNγ-producing cells. All data are representative of analysis of at least 3 WT and Tg mice.