Figure 4. Combining CDDP with aCD70 significantly decreases tumor cell proliferation due to increased ADCC.

Left: NCI-H1650, A549, and NCI-H1975 cells were treated with vehicle or CDDP (24 h, 7 µM, 1st arrow). Cells were washed (2nd arrow) and aCD70 (0.5 µM) or isotype control (0.5 µM) was added to the medium in combination with NK cells (E/T=5/1) from healthy volunteers (3rd arrow). Cell survival was assessed up to 48 h after sequential treatment in 5 conditions: Vehicle, Isotype control (red), aCD70 (green), CDDP + isotype control (blue), CDDP + aCD70 (Purple). Left: Figure shows the well impedance of 1 representative donor, expressed by the cell index as a measure of viability, analyzed using the xCELLigence RTCA system. Cell indexes were normalized with the last point before compound addition. (A-B-C) Experiments were assessed under normoxic conditions. (D) Cells were seeded overnight under normoxic conditions. Thereafter experiments were assessed in an anaerobic chamber (O₂: 0.1 – 1%). Lines represent the mean ± SEM. Right: Percentage of cell survival 12 h, 24 h and 48 h after sequential treatment. Bars represent the mean ± SEM. For all experiments, two replicates of the same condition were measured and run in parallel with NK cells from three different donors. *P < 0.05: significant decrease in cell survival compared to vehicle; **P < 0.05: significant decrease in cell survival compared to all other conditions.