Figure 4.

Effector functions of engineered SF2 antibodies. (A) ADCC activities of SF2 antibodies. Increasing concentrations (10 ng/mL to 1000 ng/mL) of SF2IgG1, SF2IgG1_RE, SF2IgG2σ and SF2IgG2σ_RE were incubated with HEK-Blue: OX40 cells co-cultured with effectors cells and the ADCC reporter bioassays were performed. Fold- activation of ADCC activities were plotted against the concentrations of test antibodies (Data expressed as mean ± SEM, n$\ge 3$). (B) ADCP activities of SF2 antibodies. Increasing concentrations (1 ng/mL to1000 ng/mL) of SF2IgG1, SF2IgG1_RE, SF2IgG2σ and SF2IgG2σ_RE were incubated with GFP positive HEK-Blue: OX40 cells co-cultured with differentiated macrophages and the phagocytosis of GFP positive HEK-Blue: OX40 target cells were evaluated by flow cytometry assay. The percentages of GFP positive cells eliminated, which reflected the ADCP activities, were plotted vs. concentrations of test antibodies (Data expressed as mean ± SEM, n $= 4$). (C) CDC activities of SF2 antibodies. Increasing concentrations (10 ng/mL to10000 ng/mL) of SF2IgG1, SF2IgG1_RE, SF2IgG2σ and SF2IgG2σ_RE were incubated with HEK-Blue: OX40 cells in the presence of rabbit complement. CDC activities were quantitated by measuring lactate dehydrogenase (LDH) activity released from the cytosol of lysed HEK-Blue: OX40 cells, and expressed as percent cytotoxicity relative to that of cells lysed by Triton X-100 (Data expressed as mean ± SEM, n$\ge 6$).