CD28 Gene Polymorphisms in the Promoter Region Are Associated with Transfusion Reactions: A Functional Study

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.