Tehran University of Medical Sciences Iranian Journal of Allergy, Asthma and Immunology 1735-1502 23 6 2024 12 29 662 675 EN Yashgin Hassanzadeh Department of Microbiology, North Tehran Branch, Islamic Azad University, Tehran, Iran Ramin Yaghobi Shiraz Transplant Research Center, Shiraz University of Medical Sciences, Shiraz, Iran Parviz Pakzad Department of Microbiology, North Tehran Branch, Islamic Azad University, Tehran, Iran Bita Geramizadeh Shiraz Transplant Research Center, Shiraz University of Medical Sciences, Shiraz, Iran 2024 04 16 2024 08 12 Cytotoxic CD4+ T cells eliminate human cytomegalovirus (HCMV)-infected cells through direct cytotoxic granules exocytosis. We aimed to evaluate the functional cytotoxic gene profile of CD4+ T cells alongside the frequency of the cytotoxic phenotype in renal transplant recipients with cytomegalovirus reactivation. Blood samples were collected from twenty renal recipients with and without HCMV reactivation (HCMV+ and HCMV- groups) and ten healthy adults (control group). CD4+ T cells were isolated to assess the frequency of cytotoxic CD4+ T cells via CD107a surface staining using flow cytometry and to evaluate gene expression of perforin, granzyme B, Runt-related transcription factor 3 (RUNX3), and Eomesodermin (Eomes) by quantitative PCR. The frequency of CD4+ CD107a+ T cells was higher in the HCMV+ group compared to the HCMV- group and significantly higher than in the control group (22.69 ± 3.47 vs 16.41 ± 2.24 and 11.60 ± 1.17, respectively). Perforin gene levels were reduced in the HCMV+ group compared to the other two groups, while granzyme B gene levels were similar between HCMV+ and HCMV- groups but lower than in the control group (0.63 ± 1.24 vs 0.67 ± 2.27 and 1.00 ± 0.00, respectively). This study demonstrated an increased frequency of cytotoxic CD4+ T cells with potentially reduced functionality in kidney transplant patients with HCMV infection. It also suggests that these cells might employ other mechanisms, such as death receptor-mediated killing, or the production of other granules. https://ijaai.tums.ac.ir/index.php/ijaai/article/view/4079 https://ijaai.tums.ac.ir/index.php/ijaai/article/download/4079/2131