Antibody-dependent cell cytotoxicity of PBMC versus PHA-blasts. PBMC or 3-day PHA-activated PBMC were labeled with⁵¹Cr and incubated with rabbit ATG (no. 95-07), horse ATG (no. 1141), or their F(ab′)₂ fragments at the indicated concentrations in presence of effector cells for 6 hours at 37°C. Results are expressed as specific release as in Fig 8. Representative of two independent experiments.