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Background Leukoreduction of blood products is crucial to prevent white blood cell ( WBC)-associated complications during transfusion. Of the widely accepted methods for quantifying WBCs in blood components, Nageotte hemocytometry is time-consuming and laborious whereas a specialized instrument is required for flow cytometry. A reliable and affordable method to assess WBC count in blood products is of particular interest. Study Design and Methods Real-time polymerase chain reaction ( PCR) of glyceraldehyde-3-phosphate dehydrogenase ( GAPDH) gene was developed for quantifying WBCs in leukopoor platelets ( LPPs). After normalization by the cell-free prefiltrated and postfiltrated plasma DNA, the relative copy number of GAPDH gene in the platelet (PLT) concentrate and its corresponding LPPs was calculated according to the equation of 2−ΔΔCt of which Ct is defined as the threshold cycle. The percentage and the number of WBCs that remained in LPPs were consequently determined. This method was compared to Nageotte hemocytometry and was validated by using serially diluted PLT concentrate and 10 pairs of PLT concentrate- LPP samples. Results Consistent with the removal of WBCs after filtration, the Ct values for the LPP samples were increased when compared to their corresponding PLT concentrate. As revealed by real-time PCR of GAPDH gene, there is a correlation between the calculated and theoretical WBC count in the serially diluted PLT concentrate (correlation coefficient, 0.9532). The WBC counts for the 10 LPP samples were comparable between Nageotte and real-time PCR method and were all below 3.3 × 106 WBCs/ L. Conclusion The real-time PCR method we report in this study is applicable for routine quality assurance during leukoreduction process. [ABSTRACT FROM AUTHOR]

Transfusion reactions are mainly induced by the interaction of an antigen and antibody. However, transfusion reactions still occur with the implementing of crossmatching and usage of pre-storage leukoreduced blood products. The roles of CD28 and CTLA4 gene polymorphisms in transfusion reaction have been shown, and subjects with certain single nucleotide polymorphisms (SNPs) of the CD28 or CTLA4 gene had a significantly higher risk of transfusion reactions. In total, 40 patients with transfusion reactions after receiving pre-storage leukoreduced blood products were enrolled in this study. We focused on the SNPs located in the CD28 promoter region (rs1879877, rs3181096, rs3181097, and rs3181098) to find out the significant SNP. A luciferase reporter assay was used to investigate the expression level of protein affected by promoter SNP variation. We found that the polymorphism of rs3181097 was associated with transfusion reactions (p = 0.003 in additive model and p = 0.015 in dominant model). Consequently, we investigated the biological function in the CD28 promoter polymorphisms (rs1879877 G > T, rs3181096 C > T, rs3181097 G > A, and rs3181098 G > A) by using dual-spectral luciferase reporter assay. The results showed that the ex-pression level of CD28 was decreased under the effect of rs3181097 with A-allele. This suggested that rs3181097 may regulate immune response through decreasing CD28 protein expression and then lead to development of transfusion reactions. [ABSTRACT FROM AUTHOR]

Leukocytes and cytokines in blood units have been known to be involved in febrile non-hemolytic transfusion reaction (FNHTR), and these adverse reactions still occur while using pre-storage leukoreduced blood products. Blood transfusion is similar to transplantation because both implant allogeneic cells or organs into the recipient. CTLA4 gene polymorphism was found to be associated with graft-versus-host disease in hematopoietic stem cell transplantation. We performed a prospective cohort study at a major tertiary care center to investigate the correlation of CTLA4 gene polymorphism and transfusion reactions. Selected CTLA4 gene SNPs were genotyped and compared between patients with transfusion-associated adverse reactions (TAARs) and healthy controls. Nineteen patients and 20 healthy subjects were enrolled. There were 4 SNPs showing differences in allele frequency between patients and controls, and the frequency of "A" allele of rs4553808, "G" allele of rs62182595, "G" allele of rs16840252, and "C" allele of rs5742909 were significantly higher in patients than in controls. Moreover, these alleles also showed significantly higher risk of TAARs (OR = 2.357, 95%CI: 1.584–3.508, p = 0.02; OR = 2.357, 95%CI: 1.584–3.508, p = 0.02; OR = 2.462, 95%CI: 1.619–3.742, p = 0.008; OR = 2.357, 95%CI: 1.584–3.508, p = 0.02; OR = 2.357, 95%CI: 1.584–3.508, p = 0.02, respectively). The present study demonstrated the correlation of CTLA4 gene polymorphism and transfusion reaction, and alleles of 4 CTLA4 SNPs with an increased risk of TAARs were found. It is important to explore the potential immune regulatory mechanism affected by SNPs of costimulatory molecules, and it could predict transfusion reaction occurrence and guide preventive actions. [ABSTRACT FROM AUTHOR]