Validation of Urinary PD-1 and FOXP3 mRNA in a Cohort of Egyptian Renal Allograft Recipients.

Background: We investigated the diagnostic and prognostic value of urinary programmed death 1 (PD-1) and FOXP3 (Forkhead transcription factors) mRNA in acute renal allograft rejection.

Methods: Urine samples from 31 acute renal allograft rejection subjects and 23 stable recipients were collected. Messenger RNA of PD-1 and FOXP3 were analyzed with real-time RT-PCR. The associations with acute rejection, disease severity, and outcome were investigated.

Results: Both PD-1 and FOXP3 mRNA were higher in acute rejection than subjects with stable grafts. In acute rejection, PD-1 and FOXP3 mRNA were significantly correlated with serum creatinine and Banff histological grade. Both PD-1 and FOXP3 mRNA performed well in diagnosing acute rejection (AUC 0.81 and 0.91, respectively). However, a combination of both FOXP3 mRNA at cutoff level 1.5 and PD-1 mRNA at cutoff level 2.6 had 94% sensitivity, 97% specificity, and AUC 0.98 in diagnosing acute rejection. Only FOXP3 mRNA was correlated with rejection reversibility and predicted graft salvage (98% sensitivity, 87% specificity, and AUC 0.93) at cutoff level 1.7.

Conclusions: PD-1 and FOXP3 mRNA were high in acute rejection, and performed well in diagnosing rejection episodes, and were correlated with rejection severity. The combination of FOXP3 and PD-1 mRNA had better sensitivity and specificity in diagnosing acute rejection than each separately. Only FOXP3 anticipated rejection outcome.