Comparison of complement-mediated hemolysis in WT and C3 KO rats. Identical numbers of labeled E^rabb or E^shA cells were IV infused into WT or C3 KO rats, and the survival of these labeled RBCs at different time points was monitored by flow cytometry. These data show rapid and comparable kinetics of the clearance of the infused E^shA cells (C) but significantly prolonged survival of the infused E^rabb cells in the C3 KO rats (n = 6 in each group) (A). The in vivo experiments were repeated, and this time the rats were euthanized 5 minutes after infusion to collect blood by cardiac puncture for the comparison of levels of serum hemoglobin. These data show that compared with the naïve controls (without any RBC infusion), both the WT and C3 KO rats that received E^shA cell infusion had significantly increased levels of serum hemoglobin with even higher levels in the C3 KO rats than in the WT rats. (D) However, levels of serum hemoglobin in the E^rabb cell infused C3 KO but not WT rats were significantly reduced and comparable to those in the untreated rats (control) (B) (n = 4 in each group). *P < .05.