Urine flow cytometry as a predictor of renal allograft function

Diagnostic Tools for Monitoring Kidney Transplant Recipients

Recent advancements in immunobiology have introduced several new diagnostic tools for monitoring kidney transplant recipients. These have been added to more established tests that, although imperfect, remain important benchmarks of diagnostic utility. Both new and old tests can be characterized with regard to their practicality, and as to whether they detect aberrant function or define the cause of dysfunction. Unfortunately, no current test is both practical and specific to a particular disease entity. Accordingly, the diagnosis of graft dysfunction remains dependent on the proper use and interpretation of many studies. This article reviews the current assays that have been evaluated in the clinic for the diagnosis of renal allograft-related diseases. These are limited to assays based on routinely obtainable samples such as blood, biopsy tissue, and urine. Newer studies are presented, along with more mundane assays, to highlight the practical use of studies regardless of their degree of mechanistic sophistication.

Advances in the clinical laboratory assessment of urinary sediment

Urinalysis has been used extensively in clinical practice to aid in the diagnosis of various renal and urologic diseases. The innovation of urinalysis is marching on right along with the rapid developments in biotechnology and astride from the solo urine cytology to sophisticated studies of individual component in the urinary sediment. In this review article, we focus on the use of flow cytometry and other technical advances in the examination of urinary sediment, the detection of urologic malignancies by the presence of microsatellite alteration in the urinary sediment, as well as the quantification of cytokine messenger RNA (mRNA) expression in urinary sediment by reverse transcription and real-time quantitative polymerase chain reaction (RT-QPCR). Notably, the study of cytokine mRNA expression in urinary sediment by RT-QPCR has recently been reported to provide important diagnostic information in kidney allograft recipients and patients with lupus nephritis. This simple and non-invasive method requires further study to determine its role in risk stratification and monitoring of therapeutic response in patients with other kidney diseases.

Serial evaluation of cell surface markers for immune activation after acute renal allograft rejection by urine flow cytometry--correlation with clinical outcome

BACKGROUND

The use of urine flow cytometry (UFC) as a noninvasive tool for the diagnosis of acute and chronic rejection of the renal allograft has been previously reported.

METHODS

We analyzed the expression of various cell surface antigens during a 30-day period after the diagnosis and treatment of 24 acute rejection (AR) episodes. UFC was performed on 59 urine specimens, from 17 patients meeting the diagnostic criteria for AR. UFC analysis was performed blinded to the clinical management utilizing the following fluorescinated monoclonal antibodies: anti-CD3, anti-CD14, anti-HLA-DR, anti-CD54, and anti-interleukin 2 receptor. Results were correlated with the patient's requirement for antilymphocytic drugs and increment in serum creatinine level (mg/dl) on day 30 after AR.

RESULTS

HLA-DR was the most prevalent antigen noted during the first 2 days of AR (91.7% of the samples), followed by CD14 (50%) and CD54 (41.7%). After day 4 the degree of expression of HLA-DR-, CD14-, and CD54-positive cells correlated with the need for antilymphocytic drugs. CD54 was the best parameter with a sensitivity=100% and specificity=90.9% (P=0.001). Those patients who had permanent graft injury after treatment of the AR had persistence of CD54- and CD14-positive cells in the urine.

CONCLUSION

Serial monitoring of urine sediments by UFC was predictive of the requirement for antilymphocytic therapy and irreversible graft damage.

Long-term allograft surveillance: the role of protocol biopsies

The safety of the renal allograft biopsy and the standardization of allograft histopathology interpretation have renewed interest in the performance of protocol (surveillance) biopsies. Recent surveillance biopsy studies in the areas of pre-implantation and in the early and late post-transplant periods are discussed.

Urine flow cytometry as a tool to differentiate acute allograft rejection from other causes of acute renal graft dysfunction

BACKGROUND

Recently, urine flow cytometry (UFC) was introduced as a useful noninvasive tool for the immunological monitoring of renal allograft recipients. The presence of an active urine sediment as determined by UFC was found to be associated with acute rejection (AR) episodes.

METHODS

In the present study we assess the value of UFC in the setting of acute graft dysfunction. UFC was performed in 30 patients (32 events) at the time of admission to the hospital for the evaluation of rising creatinine (serum creatinine increment > or =0.6 mg/dl above baseline). UFC analysis was done blinded to the clinical diagnosis, and results were compared with the discharge diagnosis: AR, n=15; chronic rejection (CR), n=8; drug toxicity, n=4; urinary leak, n=2; recurrence of primary disease, n=1; lymphocele, n=1; and unknown, n=1.

RESULTS

The presence of at least 5% of HLA-DR-positive cells and intercellular adhesion molecule-1-positive cells was detected in 100% and 53%, respectively, of the samples associated with AR (P<0.01 vs. others). The specificity value for the diagnosis of AR was: 100% for the presence of intercellular adhesion molecule-1 or CD3-positive cells and 88% for the presence of interleukin-2 receptor-positive or HLA-DR-positive cells. Half of the samples associated with CR had CD14-positive cells (P=0.03 vs. others) with a specificity value of 87.3%. The samples associated with drug toxicity, urological problems, or recurrence of primary disease were remarkable for the lack of expression of the antigens studied.

CONCLUSION

UFC can clearly differentiate AR from other causes of acute renal allograft dysfunction. HLA-DR is revealed to be the most sensitive and intercellular adhesion molecule-1 the most specific marker for AR. The presence of CD14-positive cells was highly suggestive of CR. Due to its objective nature, UFC should be considered in the evaluation of graft dysfunction.