Polyomavirus-Infected Decoy Cells in Cytocentrifuged Urine Cytology Specimens from Renal Transplant Recipients

Abstract

Objective: To evaluate the prevalence of BK virus (BKV) infection in renal transplant recipients based on the detection of urinary decoy cells. Methods: Fifty transplantation patients (56% males) aged 39.9 ± 11 years were screened for urinary decoy cells. The majority (86%) had received grafts from living donors. The inclusion criteria were graft dysfunction, hematuria, and/or leukocyturia. Creatinine and urea serum levels were monitored for 6 months. Results: Decoy cells were found in the urine of 12 (24%) patients 1–2 years after transplantation. The immunosuppression regimens most frequently adopted by BKV-positive patients were cyclosporine + azathiprine (50%) and FK + mycophenolate mofetyl + prednisone (25%). A renal biopsy revealed normal structures in 7 patients (58.4%), BKV nephropathy with lymphomononuclear infiltrate and fibrosis in 4 patients (33.3%), and acute cellular rejection with lymphomononuclear infiltrate without fibrosis in 1 patient (8.3%). In the latter patient, BKV-associated nephropathy was confirmed by immunohistochemistry. During the first month, creatinine and urea serum levels were higher among patients with urinary decoy cells. Creatinine levels decreased between the first and the sixth months. Conclusion: The finding of BKV-associated nephropathy in 33.3% of the patients with urinary decoy cells stresses the importance of screening for BKV with urinary cytology.

A Qualitative Seminested PCR Assay as an Alternative to Urine Cytology for BK Polyomavirus Screening after Renal Transplantation

“…The 32% prevalence of detection of decoy cells found in this study is within the range of 16.9 to 37.5% reported in other Brazilian studies [16][17][18][19] . Few Brazilian studies used molecular assays to determine the prevalence of BKV infection among transplant recipients [13,20] .…”

Quantitative detection of BK virus in kidney transplant recipients: a prospective validation study

“…At nine months post-transplantation, 32.5% of patients were found to have BKV viremia, but only 8 (4%) developed BKVAN. Previous studies performed in Brazil showed higher frequencies of BKVAN in kidney transplant recipient, 20 , 21 which may be related to differences in screening strategy (e.g., urinary decoy cells to trigger additional urine/plasma sampling for qPCR), in addition to regular biopsies, and ischemia times. The most relevant implication of BKV infection in renal transplant recipients relies on its ability to lead to graft fibrosis, which can be followed by renal dysfunction and eventually lead to graft loss.…”

The Role of Urine Cytology for ‘Decoy Cells’ as a Screening Tool in Renal Transplant Recipients

“…However, the use of noninvasive techniques such as urine cytology for decoy cells [35] can facilitate the selection of patients at higher risk for BKVN, which could lead to the loss of the graft.…”