Diagnostic Performance of Donor-derived Cell-free DNA Combined With Immune Activation Markers for Detecting Acute Rejection After Liver Transplantation.

BACKGROUND

Accurate differentiation of acute rejection (AR) from other causes of graft dysfunction after liver transplantation remains challenging in real-world clinical practice. Although donor-derived cell-free DNA (dd-cfDNA) has emerged as a promising non-invasive biomarker of graft injury, its specificity may be limited in clinically suspected rejection due to concurrent inflammatory and non-rejection-related graft injuries. Immune activation markers may provide complementary information by reflecting ongoing alloimmune responses.

METHODS

In this prospective diagnostic study, we enrolled liver transplant recipients presenting with graft dysfunction and classified them as AR or non-rejection based on biopsy. Plasma dd-cfDNA levels and peripheral immune activation markers, including interleukin-2 receptor (IL-2R) and activated T-cell subsets, were measured. Diagnostic performance was evaluated using receiver operating characteristic analysis and multivariable models.

RESULTS

A total of 33 patients were included, comprising 18 with biopsy-proven AR and 15 with non-rejection graft dysfunction. dd-cfDNA levels were significantly higher in AR patients. Selected immune activation markers demonstrated complementary diagnostic characteristics. A simplified combined model integrating dd-cfDNA percentage with activated T-cell subsets achieved improved discrimination compared with individual markers. Decision curve analysis indicated a higher net clinical benefit across a range of threshold probabilities.

CONCLUSION

Integration of dd-cfDNA with immune activation markers provides a complementary non-invasive strategy for evaluating acute rejection in liver transplant recipients with clinically suspected graft dysfunction. This approach may improve real-world diagnostic assessment and assist clinical decision-making while reducing unnecessary liver biopsies.