Importantly, in WT mice, Ly49E expression was clearly upregulated in liver DX5− NK cells and NKT cells at day 5 p.i., and remained high at day 7 p.i. We observed significantly increased parasitemia in Ly49E KO as compared to WT mice at days 6 and 7 p.i. This correlated with lower expression of the protective cytokines IFN-γ and TNF-α in DX5− liver NK cells of Ly49E KO mice at day 5 p.i. However, these differences were not observed in the later stage of infection. This evidence concerns the gene IFNG and parasitic infectious disease.