Quantification of Peripheral White Blood Cell Subtypes and Delayed Graft Function after Kidney Transplantation: A Single Center Analysis

BACKGROUND: Delayed graft function (DGF) is a critical complication following donation after circulatory death (DCD) kidney transplantation, with immunological factors contributing to its pathogenesis. This study aimed to assess whether early quantification of peripheral white blood cell (WBC) subtypes predicts DGF onset and outcomes. METHODS: In this single-center retrospective analysis, 217 DCD kidney transplant recipients (from January 2022 to December 2023) were included. Peripheral WBC subtypes (CD45+, CD3+, CD4+, CD8+, CD16+CD56+, and CD19+) were quantified via flow cytometry on postoperative day 1. Statistical analyses included logistic regression and receiver operating characteristic (ROC) curve evaluation. RESULTS: Among the recipients, 16.13% (35/217) developed DGF. The patients with DGF demonstrated higher serum creatinine (SCr) at discharge (235.04 ± 130.44 vs 141.90 ± 81.88 μmol/L, P < .001) and 1-year follow-up (145.76 ± 101.57 vs 108.07 ± 36.93 μmol/L, P < .001), with increased graft loss (7.4% vs 0.5%, P = .047). A lower helper T cell (CD3+CD4+) ratio predicted DGF onset (area under the curve [AUC] = 0.893, P = .001). Subgroup analysis of patients with DGF linked elevated cytotoxic T cell (CD3+CD8+) ratios to poor outcomes (SCr > 150 μmol/L/proteinuria at 1 year; AUC = 0.846, P = 0.023). Induction therapy modified these associations: Basiliximab preserved subtype differences, while antithymocyte globulin (ATG) abolished them. CONCLUSIONS: Early postoperative quantification of WBC subtypes, particularly helper and cytotoxic T cells, offers prognostic value for DGF and its outcomes. These findings highlight the utility of routine immunological monitoring in guiding clinical management. Further studies are needed to unravel the underlying mechanisms and therapeutic implications.