Preferential expansion of Ly49D⁺ NK cells in mice challenged with MHC⁺B7⁺ tumor cells. Mice were challenged with tumor cells and pulsed with BrdU as described in the legend to Figure 2. At 48 hours after tumor cell challenge, spleen cells were analyzed for NK cell subsets and BrdU incorporation. (A) Representative contour graphs from PBS control or tumor-challenged mice. Percentages of cells in the quadrants are presented in the panels. (B) Increase in percent of Ly49D⁺ and Ly49D^- NK cells that were BrdU⁺ after tumor cell challenge. Data shown were percent of BrdU⁺ cells among spleen NK subsets from tumor cell-challenged mice minus the means of percent BrdU⁺ cells among spleen NK subsets in 4 PBS-treated mice.