Fig. 1.

Obinutuzumab-mediated CD16 pre-ligation induces an enhanced IFN-γ production in response to IL-2 or IL-15 stimulation. Primary cultured NK cells were immunomagnetically purified by negative selection upon 18 h of co-culture (2:1) with biotinylated rituximab (RTX-exp)-, obinutuzumab (GA101-exp)-opsonized or not opsonized Raji (Ctrl-exp). Experienced cells were left untreated (none) (a, b) or stimulated with (a) IL-2 (500 U/ml), IL-15 (100 ng/ml) or IL-12 (10 ng/ml) or with (b) the indicated plastic-immobilized mAbs. After 18 h, IFN-γ levels were measured in the collected supernatants. a Data are presented as mean ± SEM of n = 14 donors for IL-2 setting (***p = 0.0001), n = 11 donors for IL-15 setting (***p = 0.001, **p = 0.002) or n = 7 donors for IL-12 setting (*p = 0.0156) in five independent experiments. b Mean ± SEM from n = 3 donors are reported. c IL-2R α (CD25) or IL-15R α (CD215) expression was assessed by FACS analysis in purified experienced NK cells. Histogram overlays from one representative experiment are shown. Geometric MFI (gMFI) expressed as fold change with respect to Ctrl-exp population (set to 1) is reported. Data (mean ± SEM) from n = 3 donors are reported