Assessment of Immunologic Status of Liver Transplant Recipients by Peripheral Blood Mononuclear Cells in Response to Stimulation by Donor Alloantigen

Abstract

ObjectiveTo determine whether there is a role for assessing peripheral blood mononuclear cell (PBMC) cytokine patterns as a means of measuring the immunologic and clinical status of liver transplant recipients. Summary Background DataThe role of assessing cytokine patterns in the prediction of clinical graft rejection or acceptance remains unclear. The purpose of this study was to examine the cytokine profiles of PBMC stimulated in vitro with donor alloantigen and to correlate prospectively the data with clinical assessment of graft status in orthotopic liver transplant (OLT) recipients. MethodsPBMCs from OLT recipients were examined for proliferation and cytokine mRNA expression after stimulation by donor alloantigen, third-party alloantigen, or phytohemagglutinin (PHA). mRNA extracted from PBMC was amplified by reverse transcriptase-polymerase chain reaction with oligospecific primer pairs for interleukin (IL)-2, IL-4, IL-6, IL-10, interferon (IFN) ␥, tumor necrosis factor (TNF) ␣ and transforming growth factor (TGF) ␤. Results were prospectively correlated with each patient's allograft status. ResultsIncreased IL-4 and TGF-␤ and decreased IL-2, IFN␥, and TNF-␣ mRNA expression by PBMCs in response to donor alloantigen stimulation predicted immunologic graft stability over a minimum 60-day interval compared with mRNA expression of PBMCs from patients with established rejection or those who experienced a rejection episode within a 30-day period (p Ͻ 0.05). Stimulation of recipient PBMCs with thirdparty alloantigens or PHA yielded similar but less specific results. PBMC proliferation to varying antigenic stimulation did not correlate with clinical graft status, nor did cytokine production by unstimulated PBMC. ConclusionsProspective assessment of cytokine expression by PBMC from OLT recipients in response to stimulation by donor alloantigen is helpful for predicting the clinical status of the allograft and may be useful in the development of more precise immunologic monitoring protocols.Current immunosuppressive agents have allowed for marked improvements in the results of short-and longterm outcomes in clinical transplantation, but their use is associated with risks of opportunistic infections, malignancy, and other metabolic complications. Immunosuppression currently relies on the empirical use of these nonspecific immunosuppressive agents. Further, precise immunologic monitoring to determine the appropriate dose of drugs is not yet available. Studies examining methods to optimize the administration of immunosuppression are of significant interest, as are studies examining potential mechanisms involved in the induction of allograft hyporesponsiveness.

Biomarkers

“…Also, an association between the percentage of IL-2-producing CD8 þ T cells and graft stability in liver or kidney transplant recipients was proposed [24]. In a more recent approach by Boleslawski et al, in 21 patients following liver transplantation the percentage of IL-2-producing CD8 þ T cells was found to be predictive for acute rejection [20].…”

An Odyssey of Islet Transplantation for Therapy of Type 1 Diabetes

“…Biomarkers have been defined as any characteristic that is objectively measured and evaluated as an indicator of a normal biologic or pathogenic process, a pharmacologic response to a therapeutic intervention, or a surrogate end point intended to substitute for a clinical end point [64, 65]. We are extending previous studies in our laboratory by identifying biomarkers for early prediction and diagnosis of primary islet graft damage, as well as acute and chronic rejection through microarray analysis of the tissues from transplant recipients at different time points [66]. Knowledge gained from these studies will be useful to further analyze mechanisms inducing islet cell functional damage, advance immunomonitoring protocols, and modify the paradigm of immunosuppression to improve safety and outcomes of islet transplantation.…”