Normal Ly49H-dependent NK-cell cytotoxicity in the absence of Eri1. B6 WT CD45.1⁺ lethally irradiated hosts were reconstituted with a 1:1 mixture of congenic WT (CD45.1⁺CD45.2⁺) and Eri1^−/− (CD45.2⁺) fetal liver cells. (A) At 12 weeks, splenocytes were isolated and incubated in wells coated with IgG or mAbs against NK1.1, NKp46, Ly49D, or Ly49H in the presence of anti-CD107a mAb. Alternatively, NK cells were stimulated with IL-12 and IL-18. Frequency of degranulated WT (CD45.1⁺CD45.2⁺) and Eri1^−/− (CD45.1⁻CD45.2⁺) CD107a⁺ NK cells (CD49b⁺TCRβ⁻) is shown. (B) Splenic NK cells stimulated as in panel A in the presence of brefeldin A and stained for intracellular IFN-γ. Flow cytometry plots show mean values for 10 mice. Summary graphs for Eri1^−/− NK (right) show mean relative to WT ± SD (paired Student t test). (C-E) Regression of CD107a (C) or IFN-γ (D-E) expression on percentage of Ly49H⁺ NK cells after stimulation with indicated mAbs. The Pearson correlation coefficient (r) and significance test for nonzero correlation (P) are shown for each plot (N = 10 mice from 3 independent experiments).