Urine flow cytometry as a predictor of renal allograft function

Area of Science:

• Nephrology
• Transplant Immunology
• Diagnostic Medicine

Background:

• Urine flow cytometry (UFC) is a valuable tool for diagnosing acute renal allograft rejection (AR).
• A prior study established the diagnostic value of UFC for AR.
• This study provides a 1-year follow-up on patient groups defined in the previous study.

Purpose of the Study:

• To evaluate the long-term renal function in kidney transplant recipients based on urine flow cytometry (UFC) results.
• To determine if persistently positive UFCs in clinically stable patients correlate with subclinical rejection and poorer outcomes.
• To assess the clinical significance of "false positive" UFC results over a 1-year follow-up period.

Main Methods:

• Follow-up of three patient groups: persistently negative UFCs (n=7), normalized positive UFCs after AR treatment (n=8), and persistently positive UFCs in stable patients (n=7).
• All patients received standard immunosuppressive therapy including adjusted cyclosporine levels.
• Serum creatinine (SCr) levels were monitored at 1 month and 1 year post-transplantation.

Main Results:

• Serum creatinine levels were similar at 1 month post-transplant across all groups.
• At 1 year, SCr levels were significantly higher in the persistently positive UFC group (group III) compared to the persistently negative UFC group (group I) (1.9 +/- 0.3 vs. 1.4 +/- 0.2, P=0.004).
• Patients with persistently positive UFCs showed significantly higher SCr increments, suggesting ongoing subclinical rejection impacting renal function.

Conclusions:

• Persistently positive urine flow cytometry (UFC) in clinically stable kidney transplant recipients may indicate subclinical acute rejection.
• This subclinical activity is associated with worse renal function at the end of the first post-transplant year.
• Consideration for increased immunosuppression may be warranted for patients with persistently positive UFC results.