Neumann F, et al. - Given that 25-OH-cholecalciferol vitamin D₃ (25-OH-D₃) deficiency impairs rituximab-dependent cellular cytotoxicity and the outcome of patients with diffuse large B-cell and follicular lymphomas (DLBCL), researchers assessed serum levels of 25-OH-D₃ related to maximum NK cell-mediated antibody-dependent cellular cytotoxicity (ADCC). NK cells from 20 healthy individuals killed antibody-treated CD20+ lymphoma cells in a concentration- and E:T ratio-dependent manner with obinutuzumab displaying a stronger ADCC activity than rituximab. At 65 ng/ml 25-OH-D₃, the middle of the normal range (30–100 ng/ml), the maximum NK-cell activity and ADCC were seen. Individuals with 25-OH-D₃ deficiency or insufficiency did not have significant ADCC improvements at lower levels. Lower levels might result in the failure of interventions with 25-OH-D₃.