Intragraft FOXP3 Protein or mRNA During Acute Renal Allograft Rejection Correlates With Inflammation, Fibrosis, and Poor Renal Outcome

Background: Forkhead box (FOXP3) is considered to be a specific marker for regulatory T cells. The aim of this study was to correlate intragraft FOXP3 at mRNA and cellular levels during renal allograft rejection to response to therapy and late clinical outcome. Methods: Immunostainings and quantitative reverse-transcriptase polymerase chain reaction for FOXP3, CD3, and transforming growth factor (TGF)-beta were performed and results were related to histopathologic and clinical outcome. Results: A good correlation between immunohistochemical analysis and mRNA levels for both CD3 and FOXP3 was observed. Intragraft FOYP3 was significantly related to tubulitis and interstitial fibrosis. A strong correlation was found between FOXP3 and CD3 mRNA and between FOXP3 and TGF-beta mRNA. No correlation was found between FOXP3 and response to therapy. Discussion: In conclusion, intragraft FOXP3 at both cellular and molecular levels parallels T-cell infiltration during acute rejection. FOXP3 does not predict response to antirejection therapy. FOXP3 correlates with renal fibrosis, TGF-beta, and poor late renal outcome.