Increased frequency of Ly49G2^high NK cells in mice infected with pathogens. B6 (H2^b) mice were infected with L monocytogenes and splenocytes were stained for CD45, NK1.1, CD3, Ly49C/I, and Ly49G2 at day 3 after infection and compared with uninfected control mice. (A) Increase in the total numbers of NK cells and (B) frequencies of Ly49G2^high cells in mice infected with L monocytogenes. B6 (H2^b) and B10.D2 (H2^d) mice were infected with MCMV and splenocytes were stained for NK1.1, TCRβ, Ly49C/I, and Ly49G2 at day 6 after infection and compared with uninfected control mice. Shown are increased percentages (C) and increased intensity levels (D) of Ly49G2 expression as determined by MFI on NK cells in MCMV-infected mice (solid dark line) compared with uninfected controls (tinted gray). *P < .001; **P < .01. The absolute numbers represent the percentages of cells or MFI values. Data are representative of 3 experiments using 3-4 mice per group in each experiment (means ± SEM).