Generation of NKR-P1B-deficient mice. (A) Nkrp1b deletion strategy. Exons 2 to 5 were replaced with a floxed neomycin (neo^r) cassette by homologous recombination in ES cells of B6 background. Correctly targeted ES cell clones were selected by Southern blot analysis and used to generate Nkrp1b^neo mice. These mice were bred with CMV-cre Tg mice to produce Nkrp1b^lox mice. Filled boxes denote exons (numbered), and arrowheads represent PCR primers (P) described in the “Materials and methods” section. The location of 5′ and 3′ Southern probes is underlined, and EcoRV (E) and BamHI (B) restriction enzyme sites are shown. (B) Southern blot of EcoRV-digested genomic DNA from mice of the indicated genotypes using the 5′ probe. (C) PCR analysis of tail DNA from Nkrp1b^neo and Nkrp1b^lox mice. (D) Surface expression of NKR-P1B is absent on NK cells from NKR-P1B-deficient mice. Splenocytes from WT and Nkrp1b^lox/lox mice were stained with mAbs to DX5, TCRβ, and NKR-P1B (2D9 and 2D12). The percentage of NKR-P1B⁺ NK cells (DX5⁺TCRβ^–) is indicated. PCR, polymerase chain reaction.