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. 2010 Feb 17;84(9):4148–4157. doi: 10.1128/JVI.02340-09

FIG. 3.

FIG. 3.

Influenza virus HA inhibits primary NK cell cytotoxicity. (A) After being treated with HA at the indicated concentration for 24 h, NK cells were collected and analyzed for their cytotoxicity against K562 cells at an E/T ratio of 20:1. Samples were analyzed by flow cytometry for the percentage of specific lysis. (B) NK cells were treated with 1 μg/ml HA for 6 or 24 h, and then their cytotoxicity was determined. (C) NK cells were treated with 1 μg/ml HA or left untreated (Mock) for 24 h. The cells were collected and determined for the cytotoxicity against influenza virus-infected THP-1 macrophages at the indicated E/T ratios. (D) IL-2-activated NK cells were examined for the expression of CD69 on cell surface. After being treated with 1 μg/ml HA for 6 h, the IL-2-activated NK cells were examined by flow cytometry for the presence of surface or intracellular HA. (E) Activated NK cells were incubated with 1 μg/ml HA. After 24 h, the cells were collected and determined for their cytotoxicity against K562 cells at an E/T ratio of 10:1. The data shown are means ± SEM from four different donors. *, P < 0.05; **, P < 0.01; ***, P < 0.001.