Immobilized anti-LILRB2 antibodies activated the chimeric LILRB2 reporter. (A) Representative flow cytometric profiles showing that the GFP induction by immobilized 5 µg/mL Angptl2 was abolished by 5 µg/mL anti-LILRB2 antibody. Chimeric LILRB2 receptor reporter cells were treated with indicated coated Angptl2 with or without soluble anti-LILRB2 pAb or mAb for 48 hours. Phosphate-buffered saline (PBS) was used as control. (B) Representative flow cytometric profiles showing that GFP was induced by immobilized anti-LILRB2 antibodies. Chimeric LILRB2 receptor reporter cells were treated with indicated coated (25 µg/mL in 50 µL PBS) or soluble (5 µg/mL in 250 µL cell culture media) antibodies for 48 hours. The reporter cells not containing chimeric LILRB2 receptor were used as negative control. (C) Representative flow cytometric profiles showing that GFP expression was induced by crosslinked anti-LILRB2 antibodies. Chimeric LILRB2 receptor reporter cells were treated with 10 µg/mL soluble anti-LILRB2 polyclone antibody (pAb) or equivalent crosslinked pAb for 48 hours. Streptavidin alone was used as a negative control. (D) Representative confocal images of LILRB2 chimeric receptor reporter cells with or without coated anti-LILRB2 mAb showing that the distribution of LILRB2 protein on cell plasma membrane. Ten confocal scans from top to bottom of a cell were indicated from layer 1 (L1) to layer 10 (L10). Confocal images of the phase contrast, Cy3 (indicating LILRB2 expression), and GFP (indicating signaling activation) panels were merged. Ctrl, control.