Tehran University of Medical Sciences Iranian Journal of Allergy, Asthma and Immunology 1735-1502 23 1 2024 02 11 107 114 Samad Valizadeh Blood Transfusion Research Center, High Institute for Research and Education in Transfusion Medicine, Tehran, Iran Azita Chegini Blood Transfusion Research Center, High Institute for Research and Education in Transfusion Medicine, Tehran, Iran Faranak Behnaz Department of Anesthesiology, Shohada Tajrish Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran Ali Pourfatollah Department of Immunology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran Shahram samiee Blood Transfusion Research Center, High Institute for Research and Education in Transfusion Medicine, Tehran, Iran Ronak Karbalaeifar Anesthesiology Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran 2022 07 12 2023 11 12 T helper 1 (TH1) and TH2 lymphocytes are the most important components of the immune system affected by blood transfusion. This study aimed`` to evaluate the effect of blood transfusion on gene expression of transcription factors related to the development of TH1, TH2, TH17 and regulatory T cells (Tregs). In this cross-sectional study, 20 patients diagnosed with abdominal aortic aneurysms requiring surgical repair were studied from January 2018 to August 2020. We utilized real-time PCR to evaluate the expression of transcription factor genes associated with TH1, TH2, TH17, and Treg, namely T-box-expressed-in-T-cells (T-bet), GATA-binding protein 3 (GATA-3), retinoid-related orphan receptor (RORγt), and fork head box protein 3 (Foxp3), respectively. The sampling occurred before anesthesia, 24- and 72 hours post-transfusion, and at the time of discharge. The results showed that the T-bet gene expression, compared to the time before transfusion, was significantly decreased 24 hours after blood transfusion and upon discharge while GATA3 genes exhibited a significant reduction both 24 and 72 hours after the transfusion, as compared to the pre-transfusion levels and the time of patient discharge. The Foxp3 gene demonstrated an increase at all study stages, with a notable surge, particularly 72 hours after red blood cell (RBC) transfusion. Conversely, the expression of RORγt gene, consistently decreased throughout all stages of the study. RBC transfusion in abdominal aortic aneurysm patients altered the balance of transcription gene expression of TH1, TH2, TH17, and Treg cells. https://ijaai.tums.ac.ir/index.php/ijaai/article/view/3598 https://ijaai.tums.ac.ir/index.php/ijaai/article/download/3598/2030