CD38 is a cytotoxic triggering molecule for activated NK cells but not CTL. IL-2–activated PBLs (A), purified IL-2–activated NK cells (B), or CD56-depleted CTL (C) from separate donors were tested in reverse ADCC assays using anti-CD38 (IB4), anti-CD3 (OKT3), or anti-CD16 (3G8) MoAbs to redirect the lysis of P815 target cells. Effector:target (E:T) ratios are indicated in the legends. In (D), the indicated concentrations of intact IB4, IB4 F(ab′)2, intact OKT10 (a less agonistic anti-CD38 MoAb), and M300 (nonspecific IgG control) were used with PBLs at an E:T ratio of 15:1 to redirect lysis. All effector cells were preactivated as described in Materials and Methods. *P < .05, **P < .01 when compared with the no antibody control (A, B, and C) or the M300 control (D) at the same E:T ratio.
