Immunomonitoring of renal transplant recipients in the early post-transplant period by analysis of cytokine gene expression in peripheral blood mononuclear cells.

The study was performed to investigate whether monitoring of sequential changes in peripheral blood mononuclear cell (PBMC) cytokine gene expression is predictive of clinical events following renal transplantation, as suggested by earlier studies in our laboratory, using non-quantitative PCR. RNA was extracted from PBMCs from 45 successive renal transplant recipients (including 15 rejectors) and 13 successive living donors pre-operatively and then daily for 14 and 7 days respectively. RNA was reverse transcribed to cDNA and interleukin (IL)-4, IL-10, transforming growth factor (TGF) β1, tumour necrosis factor (TNF) α,β-actin, β2-microglobulin and transferrin receptor gene expression measurement was performed using quantitative real time TaqMan PCR technology. The results of earlier work in our laboratory using RT-PCR ELISA technology to monitor cytokine gene expression were, in part, confirmed and also extended. β-actin, β2-microglobulin and transferrin receptor gene expression was found to be influenced by both surgery and acute rejection and so were inappropriate for use as housekeeping genes in the transplant setting. Statistically significant changes in gene expression of all four cytokines were seen in the renal transplant recipients, but only for IL-10 in the living donors. Increased gene expression of IL-10 and TGF-β1 was observed in both rejecting and non-rejecting recipients. However, changes in gene expression patterns detected for IL-4 and TNF-α were markedly different in rejecting and non-rejecting recipients. These changes in IL-4 and TNF-α gene expression preceded the clinical detection of acute rejection by more than 24 hours. This study has demonstrated statistically significant changes in gene expression of IL-4 and TNF-α, which distinguish rejectors from non-rejectors following renal transplantation. While these changes may not reflect intragraft events, they were detectable prior to clinical and biochemical indications of acute rejection and therefore, may have a potential role in immunomonitoring of renal transplant recipients