Target cell killing by NK cells from IFN-α11-treated mice.

<p>C57BL/6 mice were treated daily with 8000 units of IFN-α11 from −1 through +9 dpi with 20,000 SFFU of FV. Ten dpi, NK cells were isolated from 10 individual mice per group using magnetic bead separation. NK cells were incubated for 4 hours with 2 different target cell lines (YAC-1 and FBL-3) in different effector to target cell (E∶T) ratios (A). In some assays, CMA, Z-VAD-fmk, neutralizing anti-TRAIL, anti-Fas ligand (FasL) mAbs, or isotype control antibodies were added to NK and FBL-3 cells (E∶T = 25∶1) (B). Killing of FBL-3 cells by NK cells (E∶T = 25∶1) isolated from mice deficient in granzyme B (GzmB^−/−; grey bars) and wild type mice (C57BL/6; black bars) was investigated (C). Mice were treated daily with 8000 units of IFN-α11 from −1 through +9 dpi with 20,000 SFFU of FV. Ten dpi, NK cells were isolated from six individual mice per group using magnetic bead separation. Specific lysis of target cells was measured using the CytoTox 96 Non-Radioactive Cytotoxicity Assay. Mice deficient in granzyme B (GzmB^−/−; grey bars) and wild type mice (C57BL/6; black bars) treated with IFN-α11 or left untreated were analyzed at day 10 post FV infection for viral loads in the spleen by using an infectious center assay (D). Adoptive transfer experiments of NK cells were performed as follows. C57BL/6 mice were treated daily with 8000 units of IFN-α11 from −1 through +9 dpi with 20,000 SFFU of FV or left untreated. Nine dpi, NK cells were isolated from 10 individual mice per group. 2×10⁶ NK cells were adoptively transferred into recipient mice, which were infected with FV 6 days before transfer. Four days post transfer, spleen samples were assayed for viral loads by using an infectious center assay (E). Five mice in each group of infected mice were analyzed and the mean value for each group is indicated by a bar. At least 2 independent experiments were performed. Statistically significant differences between the groups are indicated by * for p<0.05, ** for p<0.005 or *** for p<0.0005.