Peripheral blood lymphocyte phenotype can predict rejection episodes after orthotopic liver transplantation

New Approaches to the Diagnosis of Rejection and Prediction of Tolerance in Liver Transplantation

Immunosuppression after liver transplantation is essential for preventing allograft rejection. However, long-term drug toxicity and associated complications necessitate investigation of immunosuppression minimization and withdrawal protocols. Development of such protocols is hindered by reliance on current paradigms for monitoring allograft function and rejection status. The current standard of care for diagnosis of rejection is histopathologic assessment and grading of liver biopsies in accordance with the Banff Rejection Activity Index. However, this method is limited by cost, sampling variability, and interobserver variation. Moreover, the invasive nature of biopsy increases the risk of patient complications. Incorporating noninvasive techniques may supplement existing methods through improved understanding of rejection causes, hepatic spatial architecture, and the role of idiopathic fibroinflammatory regions. These techniques may also aid in quantification and help integrate emerging -omics analyses with current assessments. Alternatively, emerging noninvasive methods show potential to detect and distinguish between different types of rejection while minimizing risk of adverse advents. Although biomarkers have yet to replace biopsy, preliminary studies suggest that several classes of analytes may be used to detect rejection with greater sensitivity and in earlier stages than traditional methods, possibly when coupled with artificial intelligence. Here, we provide an overview of the latest efforts in optimizing the diagnosis of rejection in liver transplantation.

Progress and challenges in diagnosis and treatment of rejection following liver transplantation

PURPOSE OF REVIEW

Liver biopsy remains the most widely utilized method for diagnosis of allograft rejection following liver transplantation. However, associated risks and limitations present an opportunity for emerging noninvasive diagnostic techniques to improve upon the current standard of care. This review evaluates progress toward development of new noninvasive methods for the monitoring and diagnosing of allograft rejection.

RECENT FINDINGS

Recent studies investigate the potential of a variety of analytes. Quantification of dd-cfDNA and of DSA show potential to indicate status of allograft rejection and aid in immunosuppression modulation. Moreover, mRNA microarray profiling of differentially expressed genes, as well as characterization of cytokine responses and immunophenotypic shifts following liver transplantation, may predict and recognize rejection events.

SUMMARY

Noninvasive methods are not yet ready to replace liver biopsy as the standard of care for diagnosis of allograft rejection, though several assays and biomarkers have shown promising preliminary results. As noninvasive techniques become validated in clinical settings, their integration with current diagnostic methods is likely to foster increased sensitivity, specificity, and reliability of diagnosis.

Influence of pretransplant dialysis modality on the change of lymphocyte subset populations and acute rejection rates after renal transplantation

BACKGROUND

The influence of dialysis modality on the acute rejection (AR) rate after renal transplantation is controversial. We investigated whether the pretransplant dialysis modality correlated with the lymphocyte subset populations and the incidence of AR after renal transplantation.

METHODS

Thirty-eight first living renal transplant recipients, consisting of 22 patients on pretransplant hemodialysis (HD) and 16 patients on pretransplant peritoneal dialysis (PD), were studied. Peripheral blood samples were taken on days -1 through 28 after transplantation, and the lymphocyte fractions were exposed to the monoclonal antibodies anti-CD3, CD19, CD4, CD8 and CD28 for a flow cytometer analysis. Biopsy specimens were obtained at the time of presumed AR episodes and on day 28 after transplantation.

RESULTS

The PD patients had a higher frequency of AR (37.5% in PD vs 9.1% in HD patients, P = 0.034). In contrast, two HD patients showed graft loss at 18 and 30 months after transplantation. The increases of CD3, CD19, CD4 and CD4+ CD28+ cells in the PD patients occurred earlier than in the HD patients and the numbers of these cells in the PD group were higher than those in the HD between days 3-28 after transplantation, most significantly on day 7.

CONCLUSIONS

These findings suggest that the PD patients with similar clinical characteristics could potentially have a higher immunocompetence and immune responsiveness associated with a higher rate of AR in the early stage of renal transplantation when compared with the HD patients.