In order to reduce the variance of antigen intensity among individuals, the RBC suspension was prepared for titration by pooling three sealed segments of donor blood each preserved with citrate-phosphate-dextrose-adenine-1 (CPDA-1). Each segment of the blood bag was analyzed within 2 weeks from the date of blood collection. This study was approved by the Institutional Review Board of Ajou University Hospital (Med-KSP-12-236).