FIGURE 4.

Effect of the substitutions 4 and 9 on ADCC activity of the IgG1. ADCC assays were carried out using peripheral blood mononuclear cells (PBMCs) from healthy human donors as effector cells and A431 cells as target cells (see “Experimental Procedures” for details). The native IgG1 and its mutants were tested using PBMCs from two donors and a E:T ratio of 25:1 against A431 cells. S.D. are indicated by error bars and represent triplicate measurements within the same experiment. Data shown are representative using PBMCs from 4 different individual donors. These results indicate that the substitution 9 is more potent than the native IgG1 in the ADCC function, while the mutant 4 behaves similarly to the native IgG1.