Donor-derived Cell-free DNA Complements De Novo Class II DSA in Detecting Late Alloimmune Injury Post Kidney Transplantation

We sought to evaluate the association between de novo donor-specific antibodies (dnDSAs) class and their mean fluorescence intensity (MFI) with donor-derived cell-free DNA (dd-cfDNA), aiming to further clarify the biomarker utility of these noninvasive tests in relation to renal allograft function and histology.The study included kidney transplant recipients (n = 171) who underwent surveillance testing with DSA and dd-cfDNA as part of their clinical care between September 2017 and December 2019 at our center.We identified dnDSA in 43 patients (25%) at a median of 4.63 y (IQR, 1.5-7) posttransplant. The presence of DSA with MFI2500 was associated with a median dd-cfDNA of 0.96% (IQR, 0.26-2.95) significantly higher than in patients with DSA MFI2500 (0.28%; IQR, 0.19-0.39) or without detectable DSA (0.22%; IQR, 0.17-0.37;Our study identifies class II dnDSA as being strongly associated with late alloimmune injury post kidney transplant independent of allograft dysfunction and shows that dd-cfDNA may complement the clinical significance of dnDSAs.