AUTHOR=Aberger Simon , Schuller Max , Mooslechner Agnes A. , Klötzer Konstantin A. , Prietl Barbara , Pfeifer Verena , Kirsch Alexander H. , Rosenkranz Alexander R. , Artinger Katharina , Eller Kathrin 

TITLE=T cell Activation Marker HLA-DR Reflects Tacrolimus-Associated Immunosuppressive Burden and BK Viremia Risk After Kidney Transplantation – An Observational Cohort Study

JOURNAL=Transplant International

VOLUME=Volume 38 - 2025

YEAR=2025

URL=https://www.frontierspartnerships.org/journals/transplant-international/articles/10.3389/ti.2025.14443

DOI=10.3389/ti.2025.14443

ISSN=1432-2277

ABSTRACT=Kidney transplantation (KT) is the current treatment of choice in patients with end-stage kidney disease. Immunosuppression is required to prevent acute rejection but is associated with a high incidence of adverse events. The immunosuppressive burden substantially differs between individuals, necessitating new immune monitoring strategies to achieve personalization of immunosuppression. To compare the evolution of T cell profiles in correlation with immunosuppression and clinical outcomes, 87 kidney transplant recipients were followed for 12 months after KT. Flow cytometry along with assessment of T cell activation markers and clinical data was performed before KT and during study visits 10 days, 2 months and 12 months after KT. Longitudinal T cell phenotyping revealed a significant decrease of T cell activation markers HLA-DR, FCRL3, and CD147 in CD4+ effector T cells after KT. The most pronounced reduction (75%) was found for the activation-proliferation marker HLA-DR, which persisted throughout the observational period. The decrease in HLA-DR expression reflected immunosuppressive burden through strong associations with tacrolimus trough-level exposure (coeff = −0.39, p < 0.01) and BK viremia incidence (coeff = −0.40, p < 0.01) in multivariable regression analysis. T cell activation marker HLA-DR emerges as a potential biomarker for tacrolimus-related immunosuppressive burden in association with BK viremia risk following KT.