Rapid rejection of human RBCs in CD47KO mice. CD47 KO B6 mice (n = 4) were depleted of T and NK cells by treatment with 1.75 mg GK1.5 and 1.4 mg 2.43 at day −2, and 150 μg PK136 at days −6 and −1, with respect to RBC transfusion. Human and CD47 KO mouse RBCs were labeled with CFSE at lower and higher concentrations, respectively, mixed at 1:1 ratio, and injected into CD47 KO mice. Blood was collected at the indicated time points for assessing the levels of human (lower fluorescence) and CD47 KO mouse (higher fluorescence) RBCs by flow cytometry. (A) Representative flow cytometric profiles at the indicated times. (B) Level (mean ± SD) of human RBCs or CD47KO RBCs measured at 10 minutes after transfusion. ***P < .001