Donor Derived Cell Free DNA as a Risk Factor for Initiating De-Novo Donor Specific Antibodies in Heart Transplantation

Abstract

PurposeWe hypothesize that subclinical inflammation, resulting in molecular injury to the cardiac allograft, may contribute to sensitization of the recipients’ immune system. Antigenic presentation of donor-derived nucleic acids, as reflected by elevated donor derived cell free DNA (dd-cfDNA) levels, may lead to leukocyte activation, promoting cytokine release and donor specific antibody (DSA) formation, with elevated dd-cfDNA levels seen prior to detection of de-novo DSAs in kidney and lung transplantation. We aimed to assess the relationship between DSA and dd-cfDNA in cardiac transplantation.MethodsThis was a retrospective cohort analysis examining a subset of the Donor‐Derived Cell‐Free DNA‐Outcomes AlloMap Registry (D‐OAR) data, focusing on dd‐cfDNA and DSA results. 67 patients were identified, providing 284 samples, with corresponding dd-cfDNA (AlloSure) and DSA results. Samples that had associated rejection were excluded.ResultsOf the 67 patients, 28 (42%) had negative DSA, with a median dd-cfDNA = 0.06% (IQR 0.03% - 0.08%), 27 patients (40%) had pre-formed DSA with a median dd-cfDNA = 0.09% (IQR 0.06% - 0.18%) and 12 patients (18%) had de-novo DSA formation, median dd-cfDNA = 0.34%, (IQR 0.11% - 0.45%) [Figure]. DSA negative patients had significantly lower dd-cfDNA levels than patients who were DSA positive (p< 0.001), while patients with de-novo DSA had significantly higher dd-cfDNA than patients who had pre-formed DSA. (p= 0.001). Elevations in dd-cfDNA appeared a median of 20 days (range 2-28) prior to DSA testing. Multivariate logistic regression analysis identified dd-cfDNA an independent predictor of de-novo DSA formation, when controlling for recipient race, age, donor demographics and HLA mismatch (1-6) (p < 0.001).ConclusionHigher dd-cfDNA levels are associated with de-novo DSA formation. Further studies are required to determine whether this is a causal relationship and if dd-cfDNA acts as a trigger for DSA formation. We hypothesize that subclinical inflammation, resulting in molecular injury to the cardiac allograft, may contribute to sensitization of the recipients’ immune system. Antigenic presentation of donor-derived nucleic acids, as reflected by elevated donor derived cell free DNA (dd-cfDNA) levels, may lead to leukocyte activation, promoting cytokine release and donor specific antibody (DSA) formation, with elevated dd-cfDNA levels seen prior to detection of de-novo DSAs in kidney and lung transplantation. We aimed to assess the relationship between DSA and dd-cfDNA in cardiac transplantation. This was a retrospective cohort analysis examining a subset of the Donor‐Derived Cell‐Free DNA‐Outcomes AlloMap Registry (D‐OAR) data, focusing on dd‐cfDNA and DSA results. 67 patients were identified, providing 284 samples, with corresponding dd-cfDNA (AlloSure) and DSA results. Samples that had associated rejection were excluded. Of the 67 patients, 28 (42%) had negative DSA, with a median dd-cfDNA = 0.06% (IQR 0.03% - 0.08%), 27 patients (40%) had pre-formed DSA with a median dd-cfDNA = 0.09% (IQR 0.06% - 0.18%) and 12 patients (18%) had de-novo DSA formation, median dd-cfDNA = 0.34%, (IQR 0.11% - 0.45%) [Figure]. DSA negative patients had significantly lower dd-cfDNA levels than patients who were DSA positive (p< 0.001), while patients with de-novo DSA had significantly higher dd-cfDNA than patients who had pre-formed DSA. (p= 0.001). Elevations in dd-cfDNA appeared a median of 20 days (range 2-28) prior to DSA testing. Multivariate logistic regression analysis identified dd-cfDNA an independent predictor of de-novo DSA formation, when controlling for recipient race, age, donor demographics and HLA mismatch (1-6) (p < 0.001). Higher dd-cfDNA levels are associated with de-novo DSA formation. Further studies are required to determine whether this is a causal relationship and if dd-cfDNA acts as a trigger for DSA formation.