INTRODUCTION Despite advances in immunosuppressive drugs, renal allograft rejection remains the main crucial determinant of the long term graft function and outcome. To solve this problem, there have been many efforts to explore the participation of cytokines and related gene expression in allograft rejection. Tissues from allograft biopsy were used for assessing of these gene expressions in many previous studies. However, for rejection screening, allograft biopsy is too invasive to perform without a clinical clue. So, we studied the expressions of cytokines which contribute to the early phase of allograft rejection with analyzing transcripts of mRNA extracted from peripheral blood mononuclear cells (PBMC) in post-transplant period. And, the patterns of gene expression of recipients who underwent rejection episode were compared with those of recipients who had no graft dysfunction.
METHODS Among renal transplant recipient who were followed up in Ajou university hospital, Suwon, Korea, 120 patients included in this study. In these volunteers, 6 patients were available to provide their blood samples before confirming of acute rejection. Blood samples from these 6 recipients were analyzed and compared their gene expressions with those of 6 recipients in the control group. PBMC were isolated from sequential venous samples from these recipients at each clinical phase of post-transplant periods. The relative expression amounts of cytokine genes encoding Interleukin 2 (IL-2), interleukin 4 (IL-4), interleukin 10 (IL-10), interleukin 15 (IL-15), and interferon γ (INF-γ) were assessed using real time reverse transcriptase-polymerase chain reaction (RT-PCR).
RESULTS IL-2, IL-4 and IL-15 mRNA expressions of the samples from the clinically stable pre-rejection phase in the rejection group were significantly higher than those of the postoperative samples from the control group. After anti-rejection therapy, IL-4 gene expression showed significantly lower amount than the expression amount in the pre-rejection samples, and the expression of IL-10 gene, unlike other cytokines, was significantly increased during anti-rejection therapy and post-rejection period. In the pre-rejection samples from the rejection group, the expression of mRNA encoding IL-10 had negative correlations with the expressions of IL-2, IL-4, and IL-15 mRNAs, which were indifferent from the positive correlations in the postoperative samples from the control group.
CONCLUSIONS Assessing of the expression patterns of IL-4 and IL-10 genes in PBMC at post-transplant periods could be used as practical tool of the early identification of acute rejection, the monitoring of proper immunosuppressive treatment and the judging of the anti-rejection treatment result.