Urine cytology screening for polyoma virus infection following renal transplantation: the Oxford experience

Decoy Cells versus Plasma Real-Time Polymerase Chain Reaction for the Detection of Polyomaviruses in Renal Transplant Patients: A Single Institutional Experience

Background and Aims:

Microscopic detection of decoy cells is routinely performed in urine samples from renal transplant patients for the evaluation of polyomaviruses. However, they are scanty papers evaluated the diagnostic accuracy of decoy cells in urine samples. The aim of this study is to evaluate the diagnostic accuracy of decoy cells in urine samples and compare with plasma real-time polymerase chain reaction (RT-PCR) as a gold standard method. In addition, to compare the findings of this study with other similar studies.

Methods:

A retrospective study over a period of four years from January 2014 to December 2017 was performed. A total of 89 urine samples from renal transplant patients were assessed for the presence of polyomaviruses and compared with plasma RT-PCR. The sensitivity, specificity, accuracy, positive predictive value (PPV) and negative predictive value (NPV) were measured.

Results:

There were 29 males and 18 females. The mean patient age was 40.3 years. The sensitivity, specificity, accuracy, PPV and NPV were 86.6%, 67.5%, 70.7%, 35.1% and 96.1%, respectively. Other similar studies reported a sensitivity of 41.9-84.6%, specificity of 65.8-100% and accuracy of 69.9-82%.

Conclusion:

The findings of this study show that the detection of decoy cells in urine samples is a sensitive screening method for polyomaviruses. The findings of this study are compatible with other similar studies.

BK Polyomavirus: Clinical Aspects, Immune Regulation, and Emerging Therapies

BK polyomavirus (BKV) causes frequent infections during childhood and establishes persistent infections within renal tubular cells and the uroepithelium, with minimal clinical implications. However, reactivation of BKV in immunocompromised individuals following renal or hematopoietic stem cell transplantation may cause serious complications, including BKV-associated nephropathy (BKVAN), ureteric stenosis, or hemorrhagic cystitis. Implementation of more potent immunosuppression and increased posttransplant surveillance has resulted in a higher incidence of BKVAN. Antiviral immunity plays a crucial role in controlling BKV replication, and our increasing knowledge about host-virus interactions has led to the development of improved diagnostic tools and clinical management strategies. Currently, there are no effective antiviral agents for BKV infection, and the mainstay of managing reactivation is reduction of immunosuppression. Development of immune-based therapies to combat BKV may provide new and exciting opportunities for the successful treatment of BKV-associated complications.

[Early intervention of BK virus replication promotes stabilization of renal graft function]

OBJECTIVE

To investigate the optimal time window for intervention of BK virus (BKV) replication and its effect on the outcomes of kidney transplant recipients (KTRs).

METHODS

A retrospective analysis of the clinical data and treatment regimens was conducted among KTRs whose urine BKV load was ≥1.0×10⁴ copies/mL following the operation between April, 2000 and April, 2015. KTRs with urine BKV load <1.0×10⁴ copies/mL matched for transplantation time served as the control group.

RESULTS

A total of 54 recipients positive for urine BKV were included in the analysis. According to urine BKV load, the recipients were divided into 3 groups: group A with urine BKV load of 1.0×10⁴-1.0×10⁷ copies/mL (n=22), group B with urine BKV load >1.0×10⁷ copies/mL (n=24), and group C with plasma BKV load ≥1.0×10⁴ copies/mL (n=8); 47 recipients were included in the control group. During the follow-up for 3.2-34.5 months, the urine and plasma BKV load was obviously lowered after intervention in all the 54 BKV-positive recipients (P<0.05). Eighteen (81.82%) of the recipients in group A and 19 (79.17%) in group B showed stable or improved estimated glomerular filtration rate (eGFR) after the intervention; in group C, 4 recipients (50%) showed stable eGFR after the intervention. In the last follow-up, the recipients in groups A and B showed similar eGFR with the control group (P>0.05), but in group C, eGFR was significantly lower than that of the control group (P=0.001). The recipients in group A and the control group had the best allograft outcome with stable or improved eGFR.

CONCLUSION

Early intervention of BKV replication (urine BKV load ≥1.0×10⁴ copies/mL) in KTRs with appropriate immunosuppression reduction can be helpful for stabilizing the allograft function and improving the long-term outcomes.

BK polyomavirus nephropathy in two kidney transplant patients with distinct diagnostic strategies for BK virus and similar clinical outcomes: two case reports

Background

BK polyomavirus-associated nephropathy is an important cause of post-transplantation renal failure. We present two cases of BK polyomavirus-associated nephropathy who were submitted to contrasting strategies of clinical follow-up to BK polyomavirus reactivation, but progressed to a similar final outcome.

Case presentation

Case 1 is a 37-year-old white man whose graft had never presented a good glomerular filtration rate function, with episodes of tacrolimus nephrotoxicity, and no urinary monitoring for BK polyomavirus; stage B BK polyomavirus-associated nephropathy was diagnosed by biopsy at 14 months post-transplant. Despite clinical treatment (dosage decrease and immunosuppressive drug change), he progressed to stage C BK polyomavirus-associated nephropathy and loss of graft function 30 months post-transplant. Case 2 is a 49-year-old mulatto man in his second renal transplantation who was submitted to cytological urinary monitoring for BK polyomavirus; he presented early, persistent, and massive urinary decoy cell shedding and concomitant tacrolimus nephrotoxicity. Even with decreasing immunosuppression, he developed BK polyomavirus-associated nephropathy 1-year post-transplant. Loss of graft function occurred 15 months post-transplant.

Conclusions

Cytological urinary monitoring was an efficient strategy for monitoring BK virus reactivation. Decoy cell shedding may be related to BK polyomavirus-associated nephropathy when extensive and persistent. The presence of associated tacrolimus nephrotoxicity may be a confounding factor for the clinical diagnosis of BK polyomavirus-associated nephropathy.

BK Virus Nephropathy in Kidney Transplantation: An Approach Proposal and Update on Risk Factors, Diagnosis, and Treatment

BK virus belongs to Polyomaviridae family; it causes 95% of nephropathy cases related to polyomavirus, with the other 5% caused by JC virus. Nephropathy jeopardizes graft function, causing a premature failure of the graft in 1%-10% of patients with kidney transplants. Nowadays, antiviral effective treatment is unknown, which is why blood and urine screening of renal transplantation patients has become the most important recommendation to guide the decrease of immunosuppression, and the only proven method to decrease poor outcomes. Different interventions, such as cidofovir, leflunomide, fluoroquinolones, and intravenous immunoglobulin, have been attempted with no improvement at all. This review aims to summarize the most relevant features of BK virus, historical issues, transmission mechanisms, risk factors, and therapeutic interventions.

BK virus-hemorrhagic cystitis following allogeneic stem cell transplantation: Clinical characteristics and utility of leflunomide treatment

BK virus-hemorrhagic cystitis (BKV-HC) is a potential cause of morbidity and mortality in patients having undergone allogeneic stem cell transplantation (Allo-SCT). We analyzed the clinical features of BKV-HC following Allo-SCT and reported the utility of leflunomide therapy for BKV-HC.

MATERIALS AND METHODS

From January 2005 to June 2014, among the 69 patients underwent Allo-SCT in our institution, the patients who experienced BKV-HC were investigated retrospectively.

RESULTS

Hemorrhagic cystitis (HC) was observed in 30 patients (43.5%), and among them, 18 patients (26.1%) were identified as BKV-HC. The median age of the patients (12 males and 6 females) was 45 years (range, 13-63). Patients received Allo-SCT from acute myeloid leukemia (n=11), aplastic anemia (n=4), myelodysplastic syndrome (n=2), and non-Hodgkin lymphoma (n=1).The donor types were a HLA-matched sibling donor for 6 patients, HLA-matched unrelated donor for 9, and a haploidentical familial donor for 2. The median onset and duration of BKV-HC was on day 21 (range, 7-97) after transplantation and 22 days (range, 6-107). Eleven patients (62.1%) had grade I-II HC and seven patients (38.9%) had grade III-IV (high-grade) HC. Among the seven patients who had high-grade HC, one had complete response (CR), one partial response (PR), and five no response (NR). Among the five non-responders, one died of BKV-HC associated complications. The remaining four patients were treated with leflunomide, with achieving CR (n=2) and PR (n=2). The median duration from the start of leflunomide therapy to response was 13 days (range, 8-17 days). All patients tolerated the leflunomide treatment well, with three patients having mild gastrointestinal symptoms, including anorexia and abdominal bloating.

CONCLUSION

BKV-HC was commonly observed in patients with HC following Allo-SCT. In high-grade BKV-HC patients who fail supportive care, leflunomide may be a feasible option without significant toxicity.

Polyomavirus nephropathy: quantitative urinary polyomavirus-Haufen testing accurately predicts the degree of intrarenal viral disease

BACKGROUND

A qualitative highly predictive urinary test for polyomavirus nephropathy (PVN) is the PV-Haufen test. This article evaluates whether a quantitative PV-Haufen analysis, that is, the number of PV-Haufen shed per milliliter urine, predicts PVN disease grades and the severity of intrarenal PV replication.

METHODS

Polyomavirus-Haufen were counted in 40 urine samples from patients with biopsy-proven definitive PVN. The number of PV-Haufen was correlated with both histologic PVN disease grades 1 to 3 and the number of SV40-T-expressing cells as indicators of intrarenal PV replication in corresponding renal allograft biopsies (manual counts and automated morphometry). Findings from quantitative PV-Haufen analyses were compared to conventional laboratory test results, that is, BK viremia (quantitative polymerase chain reaction [PCR]) and BK viruria (quantitative PCR and decoy cell counts).

RESULTS

Polyomavirus-Haufen counts showed excellent correlation (α0.77-0.86) with the severity of intrarenal PV replication and disease grades. In particular, low PV-Haufen numbers strongly correlated with early PVN grade 1 and minimal intrarenal expression of SV40-T antigen (P < 0.001). In comparison, BK viremia and viruria levels by PCR showed only modest correlations with histologic SV40-T expression (α0.40-0.49) and no significant correlation with disease grades or minimal intrarenal PV replication. No correlations were seen with urinary decoy cell counts. In contrast to conventional quantitative PCR assays or decoy cell counts, quantitative urinary PV-Haufen testing accurately reflects the severity of PV replication, tissue injury, and PVN disease grades.

CONCLUSIONS

Quantitative PV-Haufen testing is a novel noninvasive approach to patient management for the diagnosis and prediction of PVN disease grades and monitoring of disease course during therapy.

Polyomavirus nephropathy: quantitative urinary polyomavirus-Haufen testing accurately predicts the degree of intrarenal viral disease

BACKGROUND

A qualitative highly predictive urinary test for polyomavirus nephropathy (PVN) is the PV-Haufen test. This article evaluates whether a quantitative PV-Haufen analysis, that is, the number of PV-Haufen shed per milliliter urine, predicts PVN disease grades and the severity of intrarenal PV replication.

METHODS

Polyomavirus-Haufen were counted in 40 urine samples from patients with biopsy-proven definitive PVN. The number of PV-Haufen was correlated with both histologic PVN disease grades 1 to 3 and the number of SV40-T-expressing cells as indicators of intrarenal PV replication in corresponding renal allograft biopsies (manual counts and automated morphometry). Findings from quantitative PV-Haufen analyses were compared to conventional laboratory test results, that is, BK viremia (quantitative polymerase chain reaction [PCR]) and BK viruria (quantitative PCR and decoy cell counts).

RESULTS

Polyomavirus-Haufen counts showed excellent correlation (α0.77-0.86) with the severity of intrarenal PV replication and disease grades. In particular, low PV-Haufen numbers strongly correlated with early PVN grade 1 and minimal intrarenal expression of SV40-T antigen (P < 0.001). In comparison, BK viremia and viruria levels by PCR showed only modest correlations with histologic SV40-T expression (α0.40-0.49) and no significant correlation with disease grades or minimal intrarenal PV replication. No correlations were seen with urinary decoy cell counts. In contrast to conventional quantitative PCR assays or decoy cell counts, quantitative urinary PV-Haufen testing accurately reflects the severity of PV replication, tissue injury, and PVN disease grades.

CONCLUSIONS

Quantitative PV-Haufen testing is a novel noninvasive approach to patient management for the diagnosis and prediction of PVN disease grades and monitoring of disease course during therapy.

BK virus-associated urothelial carcinoma of a ureter graft in a renal transplant recipient: a case report

BACKGROUND

Urothelial carcinomas of ureter grafts in renal transplant patients are rare. Here we report our experience with a case of BK virus-associated urothelial carcinoma in a ureter graft.

CASE REPORT

A 47-year-old man developed chronic renal failure secondary to diabetes mellitus and started maintenance hemodialysis in September 2007. Two months later, the patient received a renal transplant from his 70-year-old mother. The patient developed BK virus-associated nephropathy 1 year after transplantation and presented with a decline in renal function and hydronephrosis in the transplanted kidney 4 years 6 months after transplantation. Cystoscopy and retrograde pyelography revealed an irregular filling defect in the ureter graft. Cytologic diagnosis of his urine revealed a high-grade urothelial carcinoma. Computerized tomography showed a cT2 ureteral tumor and no involvement of other organs. The patient subsequently underwent a transplant nephroureterectomy with bladder cuff resection. Histopathologic findings revealed a high-grade urothelial carcinoma, pT2, in the ureter graft with SV40-positive staining. The patient was closely observed without adjuvant chemotherapy therapy and remained disease free 1 year after surgery. Renal transplant recipients with BK virus infection are at high risk of developing urologic malignancies. Close attention is necessary to diagnose post-transplantation urologica malignancies as early as possible.

BK Virus and Its Role in Hematopoietic Stem Cell Transplantation: Evolution of a Pathogen

We reviewed the literature regarding disease induced by BK virus (BKV) in the hematopoietic stem cell transplant (HSCT) population, particularly hemorrhagic cystitis (HC) and nephritis. The association between BKV and HC has been reported over the past four decades. BKV has been clinically implicated and widely accepted as an etiologic agent of HC and nephritis in HSCT and nephropathy in renal transplant patients. We discuss the potential benefit of early initiation of therapy in patients who fail supportive care alone as well as the different treatment strategies for HC induced by BKV. Treatments that have been used such as cidofovir and leflunomide are accompanied by risks, and the benefits are not as concrete as with other viral illness in the HSCT population.

Potential relationship between BK virus and renal cell carcinoma

The objective of the present study was to investigate the potential association between the presence of BK virus (BKV) DNA and mRNA and renal cell carcinoma and bladder transitional cell carcinoma. The formalin-fixed and paraffin-embedded tissue samples were obtained from 50 cancer patients with renal cell carcinoma, 40 cancer patients with bladder transitional cell carcinoma, 45 control patients with the benign renal pathology, and from another 25 control patients with benign bladder pathology. The samples were subjected to nested PCR for detection of BKV DNA and real-time reverse transcription PCR (real-time RT-PCR) for determining mRNA levels of BKV. The results of the nested PCR indicated that 23 (14.3%) of 160 samples were positive for BKV DNA. The relationship between the cancer and the presence of BKV DNA was significant (P < 0.05). The BKV DNA positivity was significantly associated with the histological diagnosis of renal cell carcinoma (P = 0.03), but not with that of bladder transitional cell carcinoma. The results of real-time RT-PCR showed that the mRNA of BKV VP1 was present in 69.5% of the BKV DNA positive samples. The levels of BKV mRNA were significantly higher in the renal cell cancer samples than in the control samples (P < 0.05). The results of the present study confirm the association between BKV and renal cell cancer. The findings also indicated that the presence of BKV DNA resulted in a fivefold increase in the risk of development of renal cell carcinoma.

Polyoma BK Virus: An Oncogenic Virus?

We report a case of a 65-year-old gentleman with a history of end stage renal disease who underwent a successful cadaveric donor kidney transplant four years ago. He subsequently developed BK virus nephropathy related to chronic immunosuppressant therapy. Three years later, misfortune struck again, and he developed adenocarcinoma of the bladder.

BK polyomavirus in solid organ transplantation

The human BK polyomavirus (BKV) is the major cause of polyomavirus-associated nephropathy (PyVAN) putting 1-15% of kidney transplant patients at risk of premature allograft failure, but is less common in other solid organ transplants. Because effective antiviral therapies are lacking, screening kidney transplant patients for BKV replication in urine and blood has become the key recommendation to guide the reduction of immunosuppression in patients with BKV viremia. This intervention allows for expanding BKV-specific cellular immune responses, curtailing of BKV replication in the graft, and clearance of BKV viremia in 70-90% patients. Postintervention rejection episodes occur in 8-12%, most of which are corticosteroid responsive. Late diagnosis is faced with irreversible functional decline, poor treatment response, and graft loss. Adjunct therapies such as cidofovir, leflunomide and intravenous immunoglobulins have been used, but the benefit is not documented in trials. Retransplantation after PyVAN is largely successful, but requires close monitoring for recurrent BKV viremia.

Detection of polyomavirus BK reactivation after renal transplantation using an intensive decoy cell surveillance program is cost-effective

BACKGROUND

Reactivation of polyomavirus BK (BKV) after renal transplantation can lead to allograft dysfunction or loss with early detection improving outcomes. Current guidelines recommend quantitative polymerase chain reaction for surveillance; however, urinary decoy cell detection is a potentially cost-effective alternative. We present the outcomes from an early intensive BKV surveillance program using decoy cell detection for initial screening starting 2 weeks after transplantation.

METHODS

Records for all recipients of kidney (n=211) or simultaneous kidney and pancreas (n=102) transplants performed over 2 years in a single center were reviewed. Follow-up was for a minimum of 1 year. Urine cytology screening was performed fortnightly from 0 to 3 months after transplantation, monthly from 3 to 6 months then every 2 months from 6 to 12 months.

RESULTS

Decoy cell positivity occurred in 56 of 313 patients (17.9%) with sustained decoy cell positivity (≥2 positive urine samples >2 weeks apart) present in 32 patients (10.2%). Twenty-four patients (7.6%) became viremic and three patients (1%) developed polyoma virus nephropathy. The median time after transplantation until decoy cell positivity was 78 days, decreasing to 67 days for patients with sustained positivity and 57 days for patients who developed polyoma virus nephropathy. No grafts were lost due to BKV during the study period. Decoy cell screening resulted in savings of approximately £135,000 over 2 years, when compared with routine surveillance by quantitative polymerase chain reaction.

CONCLUSIONS

Clinically significant BKV reactivation occurs early after transplantation and can be reliably detected by decoy cell screening. A surveillance strategy for detecting BKV reactivation based on urine cytology is cost-effective.

Antigen-specific T cell responses to BK polyomavirus antigens identify functional anti-viral immunity and may help to guide immunosuppression following renal transplantation

Infection with the polyoma virus BK (BKV) is a major cause of morbidity following renal transplantation. Limited understanding of the anti-viral immune response has prevented the design of a strategy that balances treatment with the preservation of graft function. The proven utility of interferon-gamma enzyme-linked immunospot (ELISPOT) assays to measure T cell responses in immunocompetent hosts was the basis for trying to develop a rational approach to the management of BKV following renal transplantation. In a sample of transplant recipients and healthy controls, comparisons were made between T cell responses to the complete panel of BKV antigens, the Epstein-Barr virus (EBV) antigens, BZLF1 and EBNA1, and the mitogen phytohaemagglutinin (PHA). Correlations between responses to individual antigens and immunosuppressive regimens were also analysed. Antigen-specific T cell responses were a specific indicator of recent or ongoing recovery from BKV infection (P < 0·05), with responses to different BKV antigens being highly heterogeneous. Significant BKV immunity was undetectable in transplant patients with persistent viral replication or no history of BKV reactivation. Responses to EBV antigens and mitogen were reduced in patients with BKV reactivation, but these differences were not statistically significant. The T cell response to BKV antigens is a useful and specific guide to recovery from BKV reactivation in renal transplant recipients, provided that the full range of antigenic responses is measured.

Urinary proinflammatory cytokine response in renal transplant recipients with polyomavirus BK viruria

BACKGROUND

Polyomavirus BK (BKV) has emerged as an important complication after kidney transplantation. BKV-associated nephropathy develops in approximately 5% to 8% of renal transplant recipients, and its prognosis is poor. The relationship between urine cytokines and BK viruria in kidney recipients has not been defined.

PATIENTS AND METHODS

We compared posttransplant urine cytokine levels of 65 renal transplant outpatients with (BK-positive) or without BK viruria (BK-negative, n=33), low- (n=16) or high-level (n=16) BK viral load (VL), and 24 healthy controls (HCs). Soluble interleukin-1 receptor antagonist (sIL-1RA), interleukin (IL)-2, sIL-2R, IL-3, IL-4, IL-6, sIL-6R, IL-10, IL-17, transforming growth factor-beta2, interferon-gamma, and tumor necrosis factor-alpha levels were determined using commercially available ELISA kits.

RESULTS

BK-positive patients showed higher urine IL-3 (P=0.006), sIL-6R (P=0.010), IL-6 (P=0.020), and sIL-1RA (P=0.050) than BK-negative patients. Compared with HCs, BK-negative patients had lower urine sIL-1RA (P=0.003), sIL-6R (P=0.001), and IL-17 (P<0.001), whereas BK-positive patients had higher urine IL-3 (P=0.004) and IL-6 (P=0.001) and lower IL-17 (P<0.001), suggesting cytokine suppression by immunosuppression and upregulation by BK-infection. Urine sIL-6R (P=0.003) and IL-6 (P=0.010) were higher in patients with high VL than in patients with low VL. Additionally, patients with high VL showed higher urine IL-6 (P=0.001), sIL-6R (P=0.001), sIL-1RA (P=0.016), and IL-3 (P=0.047) than BK-negative patients, and higher urine IL-6 (P<0.001) and lower IL-17 (P<0.001) than HCs.

CONCLUSION

BK-positive renal transplant recipients, especially those with high VL, showed strong inflammatory cytokine responses with increases of urine sIL-1RA, IL-3, IL-6, and sIL-6R. Our data suggest that monocyte- and Th-2-induced cytokines are involved in the pathogenesis of BKV-associated nephropathy.

Monthly screening for polyoma virus eliminates BK nephropathy and preserves renal function

BACKGROUND

Polyoma BK virus nephropathy is a serious complication after renal transplantation and is associated with a high rate of allograft failure. Progressive infection with BK virus in immunocompromised renal transplant recipients occurs in detectable stages: Viruria, viremia, then nephropathy.

METHODS

In January, 2006, we initiated a plasma screening policy for all new transplant recipients, with monthly blood testing for BK virus by polymerase chain reaction (PCR). Between January 1, 2006, and February 28, 2007, 66 renal transplants were performed at our center. The 11 patients with a positive plasma BK PCR test underwent prompt reduction in baseline immunotherapy consisting of a 50% daily dose reduction (n = 6) or complete discontinuation of therapy with mycophenolate mofetil (n = 5).

RESULTS

After reduction or discontinuation of mycophenolate mofetil, 10 patients became negative for BK virus in the plasma within 6 months. Progression to BK nephropathy has not occurred, and renal transplant dysfunction secondary to acute cellular rejection developed in only 1 patient (9%). One year post-transplant, the mean serum creatinine values for these 11 patients remained stable at 1.5 mg/dL.

CONCLUSION

Monthly plasma screening for BK virus by PCR together with immunosuppressive regimen reduction prevents BK nephropathy. In addition, this intensive screening protocol is associated with a low rate of acute rejection and excellent preservation of renal function.

Polyoma virus infection and urothelial carcinoma of the bladder following renal transplantation

Renal transplant recipients are at increased risk of bladder carcinoma. The aetiology is unknown but a polyoma virus (PV), BK virus (BKV), may play a role; urinary reactivation of this virus is common post-renal transplantation and PV large T-antigen (T-Ag) has transforming activity. In this study, we investigate the potential role of BKV in post-transplant urothelial carcinoma by immunostaining tumour tissue for PV T-Ag. There was no positivity for PV T-Ag in urothelial carcinomas from 20 non-transplant patients. Since 1990, 10 transplant recipients in our unit have developed urothelial carcinoma, and tumour tissue was available in eight recipients. Two patients were transplanted since the first case of PV nephropathy (PVN) was diagnosed in our unit in 2000 and both showed PV reactivation post-transplantation. In one of these patients, there was strong nuclear staining for PV T-Ag in tumour cells, with no staining of non-neoplastic urothelium. We conclude that PV infection is not associated with urothelial carcinoma in non-transplant patients, and is uncommon in transplant-associated tumours. Its presence in all tumour cells in one patient transplanted in the PVN era might suggest a possible role in tumorigenesis in that case.

Aggressive immunosuppression minimization reduces graft loss following diagnosis of BK virus-associated nephropathy: a comparison of two reduction strategies

BACKGROUND AND OBJECTIVES

BK virus-associated nephropathy (BKVAN) has emerged as a leading cause of kidney graft loss, with no known predictors for graft loss and no consensus regarding treatment other than reduction of immunosuppression.

DESIGN, SETTING, PARTICIPANTS AND MEASUREMENTS

A single-center retrospective analysis was performed of all cases of BKVAN from 1999 to 2005 for clinical predictors of graft loss, with evaluation of the impact of immunosuppression withdrawal (3-drug to 2-drug immunosuppression) within the first month versus reduction of immunosuppression.

RESULTS

Of 910 kidney transplants, 35 (3.8%) cases of BKVAN were diagnosed at a median of 15 months after transplant (range, 5.5 to 90 months after transplant), 16 (46%) of which progressed to graft failure at a median of 11 months (range, 2 to 36 months) after diagnosis. Depleting antibody induction was a significant risk factor for graft loss on univariate analysis, whereas early drug withdrawal (<1 mo following diagnosis) protected against graft loss. On multivariate analysis, these findings were independent predictors of graft outcomes. Additionally, when patients were comanaged by referring nephrologists and the transplant center before the diagnosis of BKVAN, the risk of graft loss was 11-fold higher (P = 0.03) than if patients were managed solely by the transplant center.

CONCLUSIONS

Increased awareness and early diagnosis of BKVAN, with aggressive tapering of immunosuppression once established, is critical to preserve kidney graft function. Early drug withdrawal to low-dose two-drug therapy maintenance may be preferable to a general reduction of agents.

Alemtuzumab induction and steroid-free maintenance immunosuppression in pancreas transplantation

Alemtuzumab is a humanized anti-CD52 antibody that depletes lymphocytes and has been increasingly used as induction agent in transplantation. The impact of alemtuzumab induction immunosuppression in pancreas transplantation was evaluated, with particular reference to steroid avoidance in maintenance. A total of 100 patients who received 102 pancreas transplants (83 simultaneous kidney-pancreas [SPK], 15 pancreas after kidney transplantation [PAK] and 4 pancreas transplant alone [PTA]) were included. All patients received two doses of 30-mg alemtuzumab i.v. with tacrolimus (trough level 8-12 ng/mL) and mycophenolate mofetil (MMF,1g/day) with no maintenance steroids. This analysis included 62 male and 38 female recipients, with mean (+/-SD) age of 42 (+/-7.6) years. Median follow-up was 17 months (range 8-41 months). One-year patient, pancreas and kidney graft survival (actuarial) was 97%, 89% and 94%, respectively. Overall incidence of rejection was 25%. Side effects of alemtuzumab administration included thrombocytopenia (14%), pulmonary edema (2%) and rash (1%). Twenty-five percent required reoperations (12% for bleeding). Infectious complications included Cytomegalovirus (CMV,6.8%) BK viruria (3.8%), fungal infections (4%), primary varicella (1%) and posttransplant lymphoproliferative disorders (PTLD,1%). Eighty-three percent did not require any steroids posttransplant. These results indicate that alemtuzumab is safe and enables pancreas transplantation to be carried out without maintenance steroids in 83% of cases and acceptable rejection rate.

BK virus nephropathy and kidney transplantation

Nephropathy from BK virus (BKV) infection is an evolving challenge in kidney transplant recipients. It is the consequence of modern potent immunosuppression aimed at reducing acute rejection and improving allograft survival. Untreated BKV infections lead to kidney allograft dysfunction or loss. Decreased immunosuppression is the principle treatment but predisposes to acute and chronic rejection. Screening protocols for early detection and prevention of symptomatic BKV nephropathy have improved outcomes. Although no approved antiviral drug is available, leflunomide, cidofovir, quinolones, and intravenous Ig have been used. Retransplantation after BKV nephropathy has been successful.