Immobilized anti-LILRB2 antibodies promote the proliferation of human cord blood cells in vitro. (A) Human CD133⁺ umbilical cord blood cells were cultured in STF medium with or without the same amounts of coated (25 µg/mL in 50 µL PBS) or soluble (5 µg/mL in 250 µL StemSpan media) anti-LILRB2 pAb. Total cell expansion was assessed after 10 days of culture (n = 3). (B) Human CD133⁺ umbilical cord blood cells were cultured in STF medium with or without the same amounts of coated (25 µg/mL in 50 µL PBS) or soluble (5 µg/mL in 250 µL StemSpan media) anti-LILRB2 mAb. Total cell expansion was assessed after 10 days of culture (n = 3). (C) Representative flow cytometric profiles showing the frequency of CD34⁺CD90⁺ cells after 10 days of culture. (D-E) Expansion of 250 input equivalent human cord blood CD133⁺ cells treated with or without anti-LILRB2 pAb (D) or mAb (E) were serially plated in CFU medium. Total CFUs were counted after 7 days in culture. *P < .05; ***P < .001. Ctrl, control; n.s., not significant.