Figure 4.

Antibody-dependent cellular cytotoxicity (ADCC) assays (combined data from six experiments). Titrating amounts of test antibodies (Abs) were added to K2 target cells, followed by addition of human PBMC immune effector cells. The extent of target cell lysis was quantitated after 2 h. Samples were tested in duplicate for each individual experiment. In the combined data shown here, 15 donors were tested, and each point represents the mean value ± standard error of the mean. % Specific lysis is shown in (A) for IgG1σ compared to IgG1 AA, FES, and IgG2σ; and in (B) for IgG4σ1 and IgG4σ2 compared to IgG4 PAA (S228P/F234A/L235A). Ab1 IgG was used as the positive control and Ab2 IgG1 (neg. control) was the negative control.