BST2 binds and potently activates ILT7. (A) GST or BST2-GST protein was co-cultured with ILT7⁺ NFAT-GFP reporter cells. The percentages of GFP-positive reporter cells are shown. Neutralizing antibodies αILT7 (5 µg/ml) or 26F8 (25 µg/ml) or an IgG1 control antibody were included in the cultures, as indicated. Data are representative of four independent experiments. (B) HEK293 cells transiently transfected with mock control or BST2 cDNA were co-cultured with ILT7⁺ NFAT-GFP reporter cells. The percentages of GFP⁺ reporter cells are shown. Neutralizing antibodies αILT7 (5 µg/ml), 26F8 (25 µg/ml), 28G4 (25 µg/ml), or control IgG1 were included in the cultures, as indicated. Data are representative of three independent experiments.