MYXV enhances NK cell-mediated killing of glioma cells via MHC I down-regulation.

<p>M153R-mediated down-regulation of MHC I or blockade of MHC I with mAb results in enhanced NK cell-mediated killing of U87 (<b>A</b>) or U251 (<b>B</b>) target cells. For mAb blocking, mock-infected or virus-infected cells were pre-incubated with 20 µg/ml MHC class I Ab (W6/32) or isotype-matched control Ab for 30 min before co-culture with NK cells. Columns represent means of triplicate of one representative experiment. <b>Error bars</b> represent 95% confidence intervals. Supernatant was collected from 4 h co-cultures of NK cells and Mock- or MYXV- or vMyx-M153KO-infected U87 (<b>C</b>) or U251 (<b>D</b>) target cells, that were pre-incubated with either 20 µg/ml MHC class I Ab (W6/32) or isotype-matched control, and analyzed by ELISA for granzyme B release. Baseline NK cells granzyme B release was 1624 pg/ml. The result shown is granzyme B release in NK/glioma co-culture minus baseline granzyme B release by NK cells alone. Columns represent means of triplicate of one representative experiment. <b>Error bars</b> represent 95% confidence intervals.