In vivo administration of rhCD59-P results in the protection of mouse erythrocytes against an ex vivo complement challenge. CD1 mice (3 per group) were injected with either rhCD5-P at 10 mg/kg (A) or the control compound rhCD59 at 10 or 50 mg/kg (B). Blood samples were removed from tail bleeds at the indicated times and were washed and exposed to a human complement challenge as described in “In vivo experiments.” Data points show mean percentage hemolysis at each time point relative to the hemolysis obtained with samples from vehicle-treated mice (taken to represent 100% hemolysis). Error bars represent standard deviations for each group.