Packed red blood cell units destined for transfusion can be stored for up to 42 days prior to transfusion based on Food and Drug Administration (FDA) guidelines. Recent studies suggest that certain patients transfused with blood stored for longer duration have poorer outcomes than patients transfused fresher blood. The investigators' hypothesis is that the delivery of an immediate and substantial load of hemoglobin-associated iron from a stored unit of blood leads to changes that explain the differences in outcome between patients transfused old versus fresh blood. The investigators propose to test this hypothesis in humans by transfusing an individual's own blood, both fresh and after storage, and comparing levels of various outcome measures.

Participants in this study will be asked to participate in a standard blood donation. The blood will be processed per standards at the investigators regional blood center (New York Blood Center) and then split into two equal units and shipped to Columbia University Medical Center for storage and transfusion. One unit will be transfused back into the same individual fresh (i.e. between 3-7 days after donation). The other unit will be transfused 42 days after donation. Blood samples will be drawn before, during, and after transfusion to measure levels of various analytes.

Inclusion Criteria:

• healthy
• male body weight >130 lbs, female body weight > 155 lbs
• male height >5'1", female height >5'5"
• hemoglobin >13.3 g/dL

Exclusion Criteria:

• ineligible for donation based on the New York Blood Center autologous blood donor questionnaire
• systolic blood pressure >180 or <90 mm Hg
• diastolic blood pressure >100 or <50 mm Hg
• heart rate <50 or >100
• temperature >99.5 F prior to donation
• temperature >100.4 F or subjective feeling of illness prior to transfusion
• positive results on standard blood donor infectious disease testing
• pregnancy.