Enzyme-Linked Immunosorbent Assay for Human Leukocyte Antigen Antibody Detection and Urine Protein Test Recommended for Follow-Up Monitoring After Renal Transplantation

Challenges and considerations in diagnosing the kidney disease in deteriorating graft function

Despite significant reductions in acute-rejection rates with the introduction of calcineurin inhibitor (CNI)-based immunosuppressive therapy, improvements in long-term graft survival in renal transplantation have been mixed. Improving long-term graft survival continues to present a major challenge in the management of kidney-transplant patients. CNIs are a key component of immunosuppressive therapy, and chronic CNI toxicity has been widely thought to be a major factor in late graft failure. However, recent studies examining the causes of late graft failure in detail have challenged this view, highlighting the importance of antibody-mediated rejection and other factors. In addition, the diagnosis of CNI nephrotoxicity represents a challenge to clinicians, with the potential for over-diagnosis and an inappropriate reduction in immunosuppressive therapy. When graft function is deteriorating, accurately determining the cause of the kidney disease is essential for effective long-term management of the patient. Diagnosis requires a thorough clinical investigation, and in the majority of cases a specific cause can be identified.

Clinical significance of regulatory T-cell-related gene expression in peripheral blood after renal transplantation

BACKGROUND

Regulatory T cells (Tregs) have been suggested to be deeply associated with immune tolerance and long-term graft survival in transplantation. Some recipients with stable graft function (ST) could possibly minimize immunosuppression during the maintenance period. However, effective assays for assessing the suitability of patients have yet to be established. The purpose of this study was to elucidate the clinical relevance of Treg-related gene expression such as forkhead box P3 (Foxp3) in peripheral blood after renal transplantation.

METHODS

Several key molecules related to the function of immune cells such as Treg, including Foxp3, transforming growth factor-β, cytotoxic T-lymphocyte antigen-4, chemokine receptor 7, toll-like receptor 4, granzyme B, T-bet, GATA3, RORC, α1,2-mannosidase, and proteasome subunit β 10 were examined in the peripheral blood of 272 renal transplant recipients by quantitative real-time reverse-transcriptase polymerase chain reaction. The expression levels were compared between recipients with chronic rejection and ST.

RESULTS

Foxp3 messenger RNA (mRNA) levels were reduced immediately after transplantation and gradually recovered. Pretransplantation levels were closely correlated with 1 year posttransplantation levels. Recipients with chronic rejection had significantly lower levels of Foxp3, chemokine receptor 7, and granzyme B mRNA, and higher levels of toll-like receptor 4 and proteasome subunit β 10 mRNA compared with those with ST, although Foxp3 was the most relevant marker.

CONCLUSION

There is a possibility that monitoring mRNA expression levels of Treg-related molecules in peripheral blood might offer useful information on patient selection and early detection of rejection when immunosuppression minimization strategy is implemented in renal transplantation.

Monitoring after renal transplantation: recommendations and caveats

This commentary discusses the strengths and weaknesses of a recent study reported by Kobayashi and colleagues, in which paired serum samples from 297 renal transplant recipients who underwent transplantation between December 1972 and September 2004 were tested for the presence of human leukocyte antigen (HLA) antibody at two discrete time points following surgery (2004 and 2006). Urine samples collected on the same day as the serum samples, were also measured for urinary protein levels. The results of the study suggest that patients with a positive change in HLA antibody status in the post-transplantation period (i.e. from negative to positive) plus a positive urine protein test were at increased risk of developing graft dysfunction (i.e. increased serum creatinine level). Solely on the basis of these data, the authors advocate that patients should be monitored annually for de novo production of HLA antibodies and for an increased urinary protein level by use of simple and cost-effective approaches to assess the risk of graft dysfunction or failure. While the proposal is an intriguing one, this commentary identifies several issues and limitations regarding post-transplantation monitoring that should be considered.