Human RBCs are more rapidly cleared than CD47 KO mouse RBCs in NOD/SCID mice. CFSE labeled human RBCs (higher fluorescence) were mixed with CD47 KO-GFP (lower fluorescence) RBCs at 1:1 ratio and injected intravenously into NOD/SCID mice. Blood was collected at the indicated times, and the levels of surviving human and CD47 KO mouse RBCs were assessed by flow cytometry. Data shown are representative flow cytometric profiles (A), levels (%; mean ± SEM) of human and mouse RBCs in blood (B; P < .0001 for all time points), and clearance rates of human and mouse RBCs (C; P < .001). Clearance rates are presented as the percentages (mean ± SEM) of infused RBCs normalized with the levels at 10 minutes after injection as 100%.