Elevated Donor-Derived Cell-Free DNA Associated with Various Allograft Biopsy Findings, Including Membranous Nephropathy: An Observational Study

Background: Donor derived cell free DNA (dd-cfDNA) is an emerging noninvasive plasma biomarker that has the potential to detect rejection in the allografts. Conditions such as infection and nephrotoxicity have also been reported to be associated with elevated dd-cfDNA. We aim to report on what other conditions could be associated with elevated dd-cfDNA from a pathological point of view. Methods: We retrospectively reviewed 2974 transplant cases, with the key word search of “cell free DNA”, “cfDNA”, “Allosure” or “Prospera” in the pathology reports. Cases with a current or recent (within one month) diagnosis of acute rejection including active antibody mediated and acute cellular rejection, a microvascular inflammation score (glomerulitis + peritubular capillaritis) ≥ 2, findings of BK nephropathy or any kind of kidney infection suggested by pathology reports are excluded. Results: There are 5/2974 cases with elevated dd-cfDNA and pathological findings that fulfill our inclusion criteria, including 1 focal segmental glomerulosclerosis (FSGS) with moderate tubular atrophy and interstitial fibrosis (IFTA), 1 isolated v lesion, 1 isolated glomerular membranous C4d deposits, 1 membranous nephropathy (PLA2R negative) with extensive glomerulosclerosis, and 1 diffuse cortical infarction (Table 1). The earliest post-transplant time to have an elevated dd-cfDNA is 27 days in case 1 with FSGS and moderate IFTA. And the highest dd-cfDNA more than 16% is seen in case 5 with diffuse cortical infarction. 2/5 cases show positive DSA levels. All 5 cases show negative C4d staining in the peritubular capillaries by immunofluorescence. Conclusion: These observations provide evidence to support that elevated dd-cfDNA can be associated with various conditions of allograft injury ranging from acute cortical infarction to chronic changes such as global glomerulosclerosis, FSGS lesions and a moderate to severe IFTA. PLA2R negative membranous nephropathy could be associated with elevation of dd-cfDNA in the kidney allograft.