Loss of MHC-I-immunosurveillance in NKC^KD mice is because of silencing of Ly49 that bind to self–MHC-I. Three different Ly49-transgenes were introduced into NKC^KD mice by breeding. (A-C) Flow cytometric analysis of Ly49 expression in Ly49^tg-NKC^KD NK cells. Ly49 staining of NK cells is shown for (A) NKC^KD-Ly49A^tg, (B) NKC^KD-Ly49G^tg, and (C) NKC^KD-Ly49I^tg mice as a black histogram. The gray histogram shows control staining of splenic NK cells from NKC^KDmice. (D-F) Specific rejection of B2m^−/− splenocytes by (D) Ly49A^tg-NKC^KD mice, (E) Ly49G^tg-NKC^KD mice, (F) Ly49I^tg-NKC^KD mice in comparison to WT or NKC^KD mice. Each symbol represents the data from a single mouse. Data are pooled from 3 to 5 independent experiments. Groups differed significantly as shown (*P < .05; ***P < .001; NS indicates not significant). (G) LAK prepared from WT, NKC^KD, and NKC^KD-Ly49i^tg mice were used as effector cells in a ⁵¹Cr-release assay against B2m^−/− ConA blasts. These experiments were performed with mice on the B6 background.