Abstract 12658: Does Cell-Free DNA Rise With a Higher MFI Titer of DSA?

Introduction: The use of donor-derived cell-free DNA (dd-cfDNA) has been demonstrated to detect heart transplant rejection as the donor has different DNA from the recipient. dd-cfDNA has also been correlated to the detection of donor-specific antibodies (DSA). It is believed that these DSA do cause injury to the donor heart, thus exposing the donor DNA to the recipient’s bloodstream. It is not known whether the degree or binding capacity of the dd-cfDNA correlates to the binding intensity of the DSA, characterized by mean fluorescence intensity (MFI). Methods: Between 2017 and 2020, we assessed 32 heart transplant patients who were sensitized and had a dd-cfDNA level drawn. Positive dd-cfDNA was defined as ≥0.25% and was then correlated to MFI binding of the DSA categorized as weak binding (MFI 2500-5000), moderate binding (MFI 5000-10000), and strong binding (MFI >10000). 62 dd-cfDNA and associated HLA blood draws were used for this study. The Luminex Single Antigen Neat test was used to determine MFI binding of DSAs. Results: Positive dd-cfDNA did not correlate to the presence of DSA. However, there was a trend for positive dd-cfDNA correlating to DSA with higher MFI levels (see table). Conclusion: dd-cfDNA might signal the presence of DSA with higher MFI levels. This might suggest that these higher levels of DSA might be involved in injury to the donor heart. Larger number of patients will be needed to confirm this finding.