Klra15-targeted mice show a drastic reduction in telomeric NKC gene expression. (A) NK cells (DX5⁺TCRβ⁻) from the spleens of WT or mutant mice were analyzed for Ly49 expression with mAbs 4E5 (which binds Ly49O/V/R in mice with a 129-strain Klra gene cluster), 12A8 (Ly49R), 4D11 (Ly49G/T), and 14B11 (Ly49I) individually or as a cocktail (Total Ly49). The percentage of NK cells positively stained is indicated. (B) The mean ± SD percentage of different splenic NK-cell subsets present in WT, mutant, and heterozygous littermates (n = 5) is shown graphically. (C) Semiquantitative RT-PCR of cDNA for the indicated genes was performed on total RNA obtained from lymphokine-activated killer cells prepared from 2 individual WT or mutant mouse spleens. (D) The expression of NKG2/CD94 family of receptors on splenic NK cells from WT or mutant littermates. Data are representative of ≥ 3 similar experiments. These experiments were performed with mice on the 129S1 background.