Intrinsic defect in the NK-cell lineage derived from Tg mice. (A) Spleen cells from indicated BM chimeric mice were stained for Mac-1, NK1.1, and CD3. Gated CD3^- cells are shown, and the numbers represent the percentages of cells in each quadrant. Similar numbers of splenocytes were found in each chimeric mouse (data not shown). Two mice were analyzed for each group, and similar results were obtained. (B) Freshly isolated spleen cells from indicated control and chimeric mice pretreated with poly-I:C were used in standard cytotoxicity assays against the indicated targets. The bars represent standard deviation of triplicate wells for each point. Data are representative of 2 independent experiments with similar results.