Fig. 2.

HLA-G engages KIR2DL4 on NK cells to suppress trastuzumab-elicited ADCC. a FCM assay of the expression of the indicated receptors on human PBMC-derived primary NK cells. b NK cells in the presence of trastuzumab were cocultured with HER2-overexpressing breast cancer cells at the indicated E:T ratios supplemented with or without the indicated blocking antibodies. The toxicity of NK cells to malignant cells was measured. c, d NK cells and SK-BR-3 cells were cocultured as described in (b) (E:T = 30:1). IFN-γ production was measured via ELISA (c), and the degranulation of NK cells was evaluated via FCM assay for CD107a expression (d). e Representative immunohistochemical staining of KIR2DL4 on infiltrating NK cells in clinical HER2-positive breast cancer tissues. f Representative immunofluorescent staining of HER2 and KIR2DL4 in breast cancer tissues of individual patients. All experiments were performed three times. Statistical significance was obtained by Student’s t test. *P < 0.05, **P < 0.01, and ***P < 0.001. n.s. Nonsignificant