Expression of developmental and activation markers on NK cells from NKR-P1B-deficient mice. (A) Similar proportions of NK cells in the spleen, lungs, and liver of WT and NKR-P1B-deficient littermate mice were observed. A representative plot from each group of mice is shown. The NK cell percentage is indicated. (B) Graphical representation of cell surface marker expression on NK cells from WT and NKR-P1B-deficient littermate mice (n = 6 mice). Splenocytes were stained with mAbs against NK1.1, TCRβ, and various cell surface markers. The mean ± SD of the percentage of positively staining NK cells is depicted. (C) Expression of intracellular granzyme A and activation markers (CD69 and KLRG-1) on NK cells from WT and NKR-P1B-deficient littermates following interleukin-2 treatment in vitro for 3 days. The percentage of positively stained NK cells is indicated. Gray line represents staining with an isotype antibody. (D) Expression of CD69 and KLRG-1 on NK cells from naïve and poly(I:C)-treated WT and NKR-P1B-deficient littermates. The percentage of positively stained NK cells is indicated. Statistical analysis was performed by Student t test, and P values are indicated.SD, standard deviation.