Background: Detection of cardiac allograft rejection is based on the histological examination of endomyocardial biopsies (EMB). We have explored the possibility of whether graft rejection could be detected by characteristic gene expression patterns in peripheral blood mononuclear cells (PBMC) of heart-transplant recipients.
Methods: The study included 58 blood samples of 44 patients. On the day of EMB, mononuclear cells were isolated from peripheral blood, and gene expression was measured by quantitative real-time PCR. Thirty-nine parameters, including cytokine and chemokine genes were analyzed. Gene expression results were correlated with histological assessment of concomitant evaluated EMB according to International Society for Heart and Lung Transplantation (ISHLT) nomenclature.
Results: Gene expression of perforin, CD95 ligand, granzyme B, RANTES, CXCR3, COX2, ENA 78 and TGF-beta1 was significantly different in PBMC of patients with mild to moderate degrees of allograft rejection (> or =grade 2) compared with patients exhibiting no or minor forms of rejection (<grade 2). Using discriminance analysis, five parameters were found that allow discrimination of rejection > or =grade 2 vs. <grade 2 with a sensitivity of 84% and a specificity of 82% as assessed by receiver operating characteristic analysis.
Conclusion: Quantitative analysis of gene expression in PBMC may be a valuable tool for non-invasive diagnosis of allograft rejection and may allow further insight in the biological process of graft rejection.