Neopterin as a Biomarker of Cellular Immune Response in Renal Allograft Rejection Subtypes: Linking Cytokines and Immune Cells to Improve Diagnostic and Therapeutic Approaches

: Neopterin reflects Th1-associated immune activation in renal allograft recipients and provides a temporally stable, non-invasive marker of immune status. Although it does not outperform IFN-γ levels at the time of rejection, its stability and sustained elevation suggest a complementary role in longitudinal monitoring. Integration of neopterin with immune parameters, including cytokine profiles and cellular subsets, may enhance the assessment of graft immunological status and support clinical decision-making.