Background Transfusion-associated graft-versus-host disease (TA-GvHD) is caused by leukocytes, specifically T cells within a transfused blood product. Currently, the prevention of transfusionassociated graft-versus-host disease is performed by irradiation of blood products. With a sufficient reduction of leukocytes, the risk for TA-GvHD can be decreased. With consistent advances in current state-of-the-art blood filters, we herein propose that double filtration can sufficiently reduce leukocytes to reduce the risk for TA-GvHD. Materials Thirty RBC concentrates were filtered with leukocyte filters, followed by storage at 1-6 o C for 72 hours, and then a second filtration was performed. Residual leukocytes in the doublefiltered RBC units (n = 30) were assessed with flow cytometric methods, and an additional assay with isolated peripheral blood mononuclear cells (PBMCs) (n = 6) was done by both flow cytometric methods and an automated hematology analyzer. Quality of the RBCs after filtration was evaluated by hematological and biochemical tests. In vitro T cell expansion was performed using anti-CD3/CD28-coated Dynabeads or anti-CD3 (OKT3). In vivo experiment for GvHD was performed by using NOD.Cg-Prkdc scid Il2rg tm1Wjl /SzJ (NSG) mice. Results Double-filtered blood products showed residual leukocyte levels below detection limits, which calculated to be below 1200-2500 cells per blood unit. In vitro expansion rate of T cells showed that 6x10 3 and 1x10 3 cell-seeded specimens showed 60.8±10.6 fold and 10.2 ±9.7-fold expansion, respectively. Cell expansion was not sufficiently observed in wells

Background: The risk of transfusion-transmissible infections (TTIs) of HBV, HCV, and HIV in Korea has been reduced significantly by strengthening the blood safety policies. On the other hand, the risk of TTI still exists due to the diagnostic window period or viral variants. Methods: The residual risks of TTI of HBV, HCV, and HIV were calculated from July 1, 2012 to June 30, 2018 by dividing the data into two year sets. The residual risk was conducted by separating the donors who donated only once and those who donated more than once during each period. Results: In the first two years, the residual risks of HBV, HCV, and HIV were calculated to be 17.54/10 6 , 0.42/10 6 , and 0.30/10 6 respectively. The residual risk of HBV and HCV over the last two years was calculated to be 9.41/10 6 and 0.27/10 6 , showing a tendency to decrease with time. On the other hand, the residual risk of HIV over the last two years was calculated to be 0.29/10 6 , showing no significant difference. The residual risk in the donors who donated only once was higher than that in the donors who donated more than once during each period. Conclusion: The real transfusion-transmitted infection can be different from the estimated residual risk in this study because this study was based on the thesis that all NAT-reactive blood components cause infection. Because the residual risk of HBV is higher than HCV and HIV, it was considered that the safety measures for the HBV need to be improved continuously.

Background: Ever since the Korean Red Cross adopted HCV NAT for blood donor screening in 2005, HCV NAT reactive donors have been identified every year. The identification of the clinical features for these HCV NAT reactive donors may be helpful for the treatment and prevention of HCV infection. Methods: We analyzed HCV NAT reactive samples to examine the distribution of HCV RNA genotypes and the quantitative values of 128 and 47 HCV NAT reactive samples in 2007 and 2017, respectively. Results: The dominant genotype of the HCV NAT reactive donors was 1b showing 50.0% (64/128) in 2007 and 44.7% (21/47) in 2017. The genotype 2a was the second most dominant at 40.6% (52/128) in 2007 and 40.4% (19/47) in 2017. The mean titers of HCV RNA were 3.17×106 IU/mL in 2007 and 2.61×106 IU/mL in 2017. More than 90% of the donors showed a range of more than 1,000 IU/mL for the HCV RNA titer. There was no difference of quantitative values in the different genotypes. Conclusion: In this study, the distribution of HCV RNA genotypes in Korean blood donors showed a similar pattern compared to that of the general population. There was no correlation between the quantitative values and genotypes in the HCV NAT reactive blood donors, and there was no significant variation in the distribution of HCV RNA genotypes of the HCV NAT reactive donors between 2007 and 2017. Yet it is thought that the characteristics of HCV NAT reactive samples in other years have to be analyzed to achieve more significant results.

Background: Platelets (PLTs) stored in platelet additive solution (PAS) presents potential benefits in clinical use by reducing the risk of several plasma-associated adverse transfusion reactions and more plasma may be recovered for fractionation. In this study, we compared in vitro characteristics of apheresis PLTs stored in CompoSol PS

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