Terminal Effector Memory (TEMRA) CD8+ T Cell: The Key Lymphocyte Subset in BK Virus Infection Early after Kidney Transplantation

Background: BK virus associated nephropathy (BKVAN) is an important cause of early allograft failure after renal transplantation. Low immune status of renal recipients leads to the reactivation of BKV in renal tubular epithelial cells, and BK viruria is the early phase of BKV infection. Timely intervention of BK viruria could prevent the development of BKVN. Meanwhile, measurements of lymphocyte subsets can display the recipient’s real-time lymphocyte subpopulations and functional status. Therefore, this study aimed to analyze the lymphocyte subsets of patients with BK viruria early after kidney transplantation to explore the key lymphocyte subsets of BKV infection and provide potential monitoring and targeting methods for clinical intervention. Methods: Patients who received renal transplantation at the Kidney Disease Center of the Second Affiliated Hospital of Nanjing Medical University from April 2022 to October 2022 were included in the study. The patients' lymphocyte subsets were analyzed using the BD FACS CantoII flow cytometer. The clinical characteristics and distribution differences of lymphocyte subsets were compared between BK viruria and BKV negative patients. Binary logistic regression method was used to analyze the specific lymphocyte subsets of BK viruria. Results: A total of 67 renal recipients were included in the study, including 23 cases (34.2%) of BK viruria. There were statistical differences in terminal effector CD8+T cell (CD8+ Temra) subsets and central memory CD8+ T cell (CD8+ TCM) subsets between the two groups (p<0.05), while no significant differences were found in other lymphocyte subsets. Binary logistic regression analysis suggested that high ratio of CD8+ Temra and CD8+ TCM is an independent risk factor for BK viruria (p=0.039, 95%CI: 0.02-0.907). Conclusion: High ratio of CD8+ Temra and CD8+ TCM is an independent risk factor for BK viruria early after renal transplantation. Abnormal differentiation of memory CD8+ T cells might be a promising target for monitoring and treatment of BKV infection early after kidney transplantation. Funding: Government Support – Non-U.S.