Figure 4

Cetuximab- and Trastuzumab-mediated antibody-dependent cell-mediated cytotoxicity (ADCC) of NK cells cultured with IL-21. Purified NK cells derived from healthy donors (n=7) were cultured with IL-21 at indicated doses (1, 5, and 10 μg ml⁻¹) for 24 h. Thereafter, cultured NK cells were subjected to an ADCC assay against high EGFR-expressing KYSE30 and low EGFR-expressing KYSE110 at the indicated effector : target ratios (5 : 1, 10 : 1, and 20 : 1) in the presence of Cetuximab or control mAbs (Control, A). Similarly, the cultured NK cells were subjected to an ADCC assay against high HER2-expressing TE4 and low HER2-expressing KYSE50 at the indicated effector : target ratios (5 : 1, 10 : 1, and 20 : 1) in the presence of Trastuzumab or control mAbs (Control, B). ^**P<0.01. ^*P<0.05. The expression of HER2 or EGFR on target tumour cells was shown as mean fluorescence intensity (MFI) analysed by flow cytometry. In (C), purified NK cells derived from healthy donors were cultured with IL-21 (1 and 10 μg ml⁻¹) or IL-2 (20 and 200 ng ml⁻¹) for 24 h. The cultured NK cells were subjected to an ADCC assay against high HER2-expressing TE4 or high EGFR-expressing KYSE30 at the indicated effector : target ratios (5 : 1, 10 : 1, and 20 : 1) in the presence of Trastuzumab or Cetuximab. Representative ADCC assay from three different experiments from healthy donors (n=3) was shown in (C).