Anti-CD16 mAb blocks the target-cell recognition by CD16/γ-transduced T-cell clones. Effector cells (the CD8⁺ T-cell clone no.24 and the CD4⁺ T-cell clone no.3) were first incubated in the presence or absence of anti-CD16 mAb (3G8) F(ab′)2 fragments at 20 μg/mL. After 30′ on ice effector cells were mixed (E/T ratio: 30:1) with an equal volume of ⁵¹Cr-labeled allogeneic EBV-LCL in the presence or absence of anti-CD20 mAb (rituximab, 0.2 μg/mL). Cytotoxicity was evaluated from ⁵¹Cr release after 4 hours of incubation; data represent mean from triplicate measurements.