NKp46 receptor mediated cytotoxicity by neonate and calf NK cells. NKp46+ cells from peripheral blood of neonates less than 8 days and calves (6 months old) were sorted, cultured in the presence of rbIL-2 or rhIL-15 for 7–10 days and used in a flow cytometry cytotoxicity assay. (A) Redirected lysis of P815 murine target cells carrying an Fcγ receptor by NK cells from neonates (open symbols) or from calves (filled symbols), in the presence of anti-NKp46 mAb (black lines) or with addition of the isotype control (grey lines). Data presented are means from 5 animals ± SEM. Neonate and calf NK cell cytotoxicity were compared with the one-way Wilcoxon test: p < 0.01. (B) Level of expression of the NKp46 receptor after 7–10 days of culture in the presence of rbIL-2 or rhIL-15 (mean fluorescence intensity: MFI). Individual values and medians are presented. The nonparametric Mann–Whitney test (p value is indicated above the scatter plot) was used for statistical analysis.