Human tumor cell lines express a potential ligand for ILT7. (A) Five human breast cancer cell lines were co-cultured with either ILT7⁺ NFAT-GFP reporter cells or parental NFAT-GFP reporter cells. The percentages of GFP-positive reporter cells were analyzed. Data are representative of four independent experiments. (B) Human carcinoma cells were co-cultured with ILT7⁺ NFAT-GFP reporter cells. The percentages of GFP-positive reporter cells were analyzed. The categories of the cancer lines are as follows: OVCAR-3, SKOV-3, and DOV-13 (ovarian); HT-29 and HCT-116 (colon); WM35, WM239, MEL526, MEL624, MEL888, and MEL938 (melanoma); U87, LN229, and SNB19 (glioblastoma); A549 (lung cancer). Data are representative of two independent experiments. (C) T47D cells were co-cultured with ILT7⁺ NFAT-GFP reporter cells in the presence of 1 µg/ml of control IgG1 or anti-ILT7 mAb. The percentages of GFP-positive reporter cells were plotted. Data are representative of four independent experiments. (D) Breast cancer MDA-MB-468 cells were first cultured for 5 d in the presence of medium, 5 ng/ml of TNF-α or 500 U/ml of IFN-α, and then co-cultured with NFAT-GFP reporter cells. The percentages of GFP-positive reporter cells were analyzed. Data are representative of four independent experiments. Error bars represent the mean ± the SEM.