Ly49-deficient mice are protected from lethal influenza infection.

<p><b>(A, B)</b> Groups of sex-matched WT (B6), <i>Ifnar1</i>^-/- and <i>B2m</i>^-/- mice were infected intranasally with 600 PFU of FM-MA virus. Single-cell suspensions were prepared from uninfected lungs and those infected with the virus for 5 days. Cells were stained with antibodies against H-2K^b or H-2D^b and CD326 (EpCAM—epithelial cell marker), and analyzed by flow cytometry. Surface expression of H-2K^b or H-2D^b was determined on EpCAM⁺ lung epithelial cells. The following mAb were used in this experiment: anti-LFA-1, anti-EpCAM, anti-H-2K^b, and anti-H-2D^b. One representative image from each group is shown. This experiment was performed three times with similar results. <b>(C, D)</b> Ly49G, I_1, O, R, and V expression was detected on lung NK cells of uninfected WT and NKC^KD mice using anti-NKp46, anti-TCRβ, and a combination of 4D11, 4E5 and 14B11 mAb. NKG2D, NKp46, CD11b, and CD27 expression was detected on lung NK cells, defined using anti-CD49b (DX5) and anti-TCRβ. The gray line represents staining with an isotype antibody. This experiment was performed three times with similar results. <b>(E)</b> Groups of age and sex-matched WT, Ly49Q^KO, and NKC^KD mice were infected with FM-MA virus (1050 PFU) and monitored for 2 weeks. Data are pooled from two independent experiments (n = 19 in each group). <b>(F)</b> Groups of age and sex-matched NKC^KD mice with or without NK depletion by anti-asialoGM1 were infected and monitored as above. A group of uninfected, NK-depleted mice was included as a control (n = 10 in each group). The percentage of surviving mice is shown. *<i>p</i> < 0.05, **<i>p</i> < 0.01 and ***<i>p</i> < 0.001. Statistical analysis was performed with the log rank test.