Arteriolar hyalinization at 0-hour biopsy predicts long-term graft function in deceased kidney transplantation.

OBJECTIVES: Regarding the relationship between donor kidney quality and renal graft function after deceased kidney transplantation (KTx) following donation after cardiac death (DCD), the evaluation timing varies depending on the study. Evaluation of histology and changes in long-term renal graft function is limited. METHODS: A retrospective single-center study included 71 recipients who underwent 0-hour biopsy for KTx from DCD. The recipients were divided into two groups to evaluate factors related to renal graft function (study1). The two groups were categorized as stable graft function and poor graft function with the change of estimated glomerular filtration rate (eGFR) after KTx. The recipients were then divided into four groups to assess whether the factors identified in study1 were related to the change in long-term renal graft function (study2). They were categorized as follows: Improved, Stable, Deteriorated, and Primary non-function with the change of eGFR after KTx. RESULTS: In study1, donor age ≥ 50 years (29.5% vs. 65.2%; p = 0.09), banff arteriolar hyalinosis (ah) score (0.66 ± 0.78 vs. 1.2 ± 1.0; p = 0.018), and presence of glomerulosclerosis (43.2% vs. 76.2%; p = 0.017) were significant risk factors for poor long-term graft function. When the recipients were divided into four groups, the severity of ah correlated well with changes in long-term renal function. CONCLUSIONS: We can predict the shift in long-term renal graft function after KTx from DCD according to the severity of ah by 0-hour biopsy.

Hyporesponsiveness against donor's ABO antigens of renal grafts after ABO-incompatible kidney transplantation.

BACKGROUND: ABO antigens expressed on the red blood cells (RBCs) are not identical to those expressed on the renal endothelial cells. The isohemagglutinin assay employing the RBCs is the gold standard for evaluating anti-ABO antibody (Ab) levels. However, it remains unclear whether the anti-ABO Abs detected by the isohemagglutinin assay after ABO-incompatible (ABOi) kidney transplantations (KTx) that are not associated with antibody-mediated rejection can bind to renal graft endothelial cells. METHODS: Ninety plasma samples were collected from patients with stable graft function after ABO-compatible (ABOc) or ABOi KTx. Anti-ABO Ab titers were examined by both the isohemagglutinin assay and the CD31-ABO microarray, which was developed as a mimic of the ABO antigens expressed on the renal endothelial cells. RESULTS: The antibody titers detected by the isohemagglutinin assay and the CD31-ABO microarray after the ABOc KTx relatively correlated with each other. However, the CD31-ABO microarray results showed low antibody levels against donor blood group antigens after ABOi KTx and did not correlate with the isohemagglutinin assay. In contrast, the antibody levels against non-donor blood group antigens after ABOi KTx were comparable to those after the ABOc KTx. Fourteen patients received graft biopsies, and no antibody-mediated rejection was observed in ABOi KTx recipients, except for two patients who had anti-donor-HLA Abs. CONCLUSION: The present study suggested that the anti-ABO Abs detected by the isohemagglutinin assay after ABOi KTx with stable graft function were hyporeactive to the ABO antigen of graft renal endothelial cells.

Immunological risk and complement genetic evaluations in early onset de novo thrombotic microangiopathy after living donor kidney transplantation: A Japanese multicenter registry.

BACKGROUND: Thrombotic microangiopathy (TMA) after kidney transplantation (KTx), particularly early onset de novo (dn) TMA, requires immediate interventions to prevent irreversible organ damage. This multicenter study was performed to investigate the allogeneic clinical factors and complement genetic background of dnTMA after KTx. METHODS: Perioperative dnTMA after KTx within 1 week after KTx were diagnosed based on pathological or/and hematological criteria at each center, and their immunological backgrounds were researched. Twelve aHUS-related gene variants were examined in dnTMA cases. RESULTS: Seventeen recipients (15 donors) were enrolled, and all dnTMA cases were onset within 72-h of KTx, and 16 of 17 cases were ABO incompatible. The implementation rate of pre-transplant plasmaphereses therapies were low, including cases with high titers of anti-A/anti-B antibodies. Examination of aHUS-related gene variants revealed some deletions and variants with minor allele frequency (MAF) in Japan or East Asian genome databases in genes encoding alternative pathways and complement regulatory factors. These variants was positive in 8 cases, 6 of which were positive in both recipient and donor, but only in one graft loss case. CONCLUSIONS: Although some immunological risks were found for dnTMA after KTx, only a few cases developed into TMA. The characteristic variations revealed in the present study may be novel candidates related to dnTMA in Japanese or Asian patients, but not pathogenic variants of aHUS. Future studies on genetic and antigenic factors are needed to identify factors contributing to dnTMA after KTx.

A Novel Method of CD31-Combined ABO Carbohydrate Antigen Microarray Predicts Acute Antibody-Mediated Rejection in ABO-Incompatible Kidney Transplantation.

Isohemagglutinin assays employing red blood cells (RBCs) are the most common assays used to measure antibody titer in ABO-incompatible kidney transplantation (ABOi KTx). However, ABO antigens expressed on RBCs are not identical to those of kidney and antibody titers do not always correlate with clinical outcome. We previously reported that CD31 was the main protein linked to ABO antigens on kidney endothelial cells (KECs), which was different from those on RBCs. We developed a new method to measure antibody titer using a microarray of recombinant CD31 (rCD31) linked to ABO antigens (CD31-ABO microarray). Mass spectrometry analysis suggested that rCD31 and native CD31 purified from human kidney had similar ABO glycan. To confirm clinical use of CD31-ABO microarray, a total of 252 plasma samples including volunteers, hemodialysis patients, and transplant recipients were examined. In transplant recipients, any initial IgG or IgM antibody intensity >30,000 against the donor blood type in the CD31-ABO microarray showed higher sensitivity, specificity, positive predictive value, and negative predictive value of AABMR, compared to isohemagglutinin assays. Use of a CD31-ABO microarray to determine antibody titer specifically against ABO antigens expressed on KECs will contribute to precisely predicting AABMR or preventing over immunosuppression following ABOi KTx.

Kidney function of Japanese children undergoing kidney transplant with preemptive therapy for cytomegalovirus infection.

BACKGROUND: Cytomegalovirus (CMV) infection is one of the major factors that affect morbidity and mortality in kidney transplant (KTx) patients. The rate of CMV seropositivity in children before KTx is lower than that in adults; therefore, pediatric KTx patients have a higher risk of CMV infection. In Japanese pediatric KTx patients, preemptive therapy for CMV infection is a main conventional therapy. This study investigated whether this preemptive treatment would affect kidney function at 2 years post-KTx. METHODS: A total of 163 patients, that is approximately half of the Japanese pediatric KTx patients nationwide, were recruited to participate in our study. We compared the values of the sequential estimated glomerular filtration rate (eGFR) at two years post-KTx and other influencing factors in CMV viremia, CMV disease, and no-infection groups. RESULTS: Cytomegalovirus infection after KTx occurred in 75 patients (46.0%), 38.7% of whom developed CMV disease. The sequential eGFR values post-KTx did not differ significantly between the three groups. CMV infection was not significantly correlated with other factors, other infections (including Epstein-Barr [EB] virus infection), acute rejection (AR), or adverse events. Only prolonged duration of total hospitalization was significantly associated with CMV infection (P = .002). In the multivariate analysis, younger age, CMV infection, and adverse effects were independently significantly related to prolonged total hospitalization. CONCLUSION: Preemptive therapy for CMV infection evidenced by viremia and disease did not significantly influence kidney function in Japanese pediatric KTx patients at two years after the operation.

Efficacy and safety of ribavirin therapy for chronic hepatitis E after kidney transplantation.

Hepatitis E virus (HEV) infection has been recognized as an acute condition. However, recent reports have shown that immunocompromised patients, such as those receiving solid-organ transplantation, can develop chronic hepatitis with HEV infection. We report two cases of chronic hepatitis E after kidney transplantation (KT) who were successfully treated with ribavirin monotherapy. Several years after KT, both patients had sustained elevations in the levels of liver enzymes for a period of more than 6 months. Both patients had HEV infection, genotype 3a. Histological studies showed infiltration of inflammatory cells without fibrosis. Treatment included ribavirin monotherapy at a dosage of 600 mg daily for 3 months. One month after therapy initiation, HEV-RNA turned to negative, and remained negative at 24 weeks after ribavirin therapy without severe complications. Although the treatment of chronic hepatitis E is not fully established, ribavirin therapy can be a safe and effective treatment for chronic hepatitis E.

Analysis of the prevalence of systemic de novo thrombotic microangiopathy after ABO-incompatible kidney transplantation and the associated risk factors.

OBJECTIVES: To analyze the prevalence of systemic de novo thrombotic microangiopathy in ABO-incompatible kidney transplantation and risk factors associated with this condition. METHODS: A total of 201 patients who received living-donor kidney transplantation (114 patients with ABO-identical kidney transplantation and 87 patients with ABO-incompatible kidney transplantation) were retrospectively analyzed. Systemic de novo thrombotic microangiopathy was diagnosed clinically according to the presence of thrombocytopenia with microangiopathic hemolytic anemia and pathological findings of thrombotic microangiopathy. Anti-A and anti-B antibodies were purified from human plasma, and these antibodies' bindings to human kidney were investigated in vitro. RESULTS: ABO-incompatible kidney transplantation was a significant risk factor of systemic de novo thrombotic microangiopathy (odds ratio 55.9, 95% CI 1.8-8.9, P < 0.001) after transplantation. Multivariate logistic regression analysis showed that non-use of mycophenolate mofetil, pretreatment immunoglobulin G antibody titer ≥64-fold and pretransplant immunoglobulin M antibody titer ≥16-fold were significant risk factors for systemic de novo thrombotic microangiopathy in ABO-incompatible kidney transplantation. Microvascular inflammation of 1-h post-transplant biopsy could be observed more frequently in thrombotic microangiopathy patients than in non-thrombotic microangiopathy patients. Anti-A and anti-B antibodies purified from human plasma showed a strong in vitro reaction against human kidney when the antibody titer was ≥16-fold. CONCLUSIONS: Antibody titer should be decreased to ≤16-fold until the day of ABO-incompatible kidney transplantation by desensitization therapy including mycophenolate mofetil. The 1-h biopsy results might help to diagnose systemic de novo thrombotic microangiopathy.

Limited significance of repeated long-term radiological and hormonal examination in nonfunctioning adrenal incidentalomas.

PURPOSE: The purposes of the present study were to evaluate growth rate of nonfunctioning adrenal incidentalomas (AIs) and their development to hormonal hypersecretion on follow-up. MATERIALS AND METHODS: A retrospective study was conducted from the electronic medical records. A total of 314 patients were diagnosed with adrenal tumors between 2000 and 2016. After excluding patients who had overt adrenal endocrine disorders or whose adrenal tumors were clinically diagnosed as metastatic malignancies, we investigated 108 patients with nonfunctioning AIs including characteristics, the treatment, the way of follow-up and pathology. RESULTS: Fifteen patients received immediate adrenalectomy because of the initial tumor size or patient's preference. Pathological examination revealed malignancy in 2 patients. In the remaining 93 patients, radiological examinations were performed periodically. Tumor enlargement of ≥ 1.0cm was observed in 8.6% of the patients who were followed up as nonfunctioning AIs with a median follow-up period of 61.5 months (range: 4-192). Eleven patients underwent adrenalectomy. On the pathological examinations, all of the tumors, which showed a size increase, were diagnosed as benign tumors. Regarding the followed up patients without adrenalectomy, only 2.4% of the patients had tumor enlargement during the prolonged follow-up. Furthermore, none of the patients developed hormonal hypersecretion or clinical signs such as obesity, glucose intolerance or poorly controlled hypertension. CONCLUSIONS: Tumor enlargement of AIs did not correlate with malignancy. The value of repeat radiological and hormonal examinations may be limited in the long-term follow-up of patients whose AIs are not enlarged.

Results of a multicenter prospective clinical study in Japan for evaluating efficacy and safety of desensitization protocol based on rituximab in ABO-incompatible kidney transplantation.

BACKGROUND: Deceased organ donations are rare in Japan, with most kidney transplants performed from a limited number of living donors. Researchers have thus developed highly successful ABO-incompatible transplantation procedures, emphasizing preoperative desensitization and postoperative immunosuppression. A recent open-label, single-arm, multicenter clinical study prospectively examined the efficacy and safety of rituximab/mycophenolate mofetil desensitization in ABO-incompatible kidney transplantation without splenectomy. METHODS: Mycophenolate mofetil and low dose steroid were started 28 days pretransplant, followed by two doses of rituximab 375 mg/m2 at day -14 and day -1, and postoperative immunosuppression with tacrolimus or ciclosporin and basiliximab. The primary endpoint was the non-occurrence rate of acute antibody-mediated rejection. Patient survival and graft survival were monitored for 1 year posttransplant. RESULTS: Eighteen patients received rituximab and underwent ABO-incompatible kidney transplantation. CD19-positive peripheral B cell count decreased rapidly after the first rituximab infusion and recovered gradually after week 36. The desensitization protocol was tolerable, and most rituximab-related infusion reactions were mild. No anti-A/B antibody-mediated rejection occurred with this series. One patient developed anti-HLA antibody-mediated rejection (Banff 07 type II) on day 2, which was successfully managed. Patient and graft survival were both 100 % after 1 year. CONCLUSION: Our desensitization protocol was confirmed to be clinically effective and with acceptable toxicities for ABO-I-KTx (University Hospital Medical Information Network Registration Number: UMIN000006635).

[Laparoscopic fenestration for a symptomatic lymphocele in renal graft after living-donor kidney transplantation].

A 36-year-old female received protocol biopsy at 1 month after living donor kidney transplantation. At 3 months post-transplantation, presence of a growing cystic mass in the kidney graft which had not been detected preoperatively, was demonstrated by ultrasound and computed tomography. The patient had an abdominal pain around the graft. Percutaneous drainage and sclerotherapy with minocyclin were performed twice, but the cystic mass, nevertheless, became enlarged and the abdominal pain recurred again. Laparoscopic fenestration was then performed. Immunohistochemistry of the cystic mass wall showed that it was CD34 (-), EMA (-), Megalin (-), but D2-40 (+). These results suggested that the cystic mass was derived from lymphatic vessels, which developed into lymphocele in the graft. We concluded that lymphatic vessels could have been injured and obstructed by the protocol biopsy. This is the first report of successful laparoscopic fenestration for lymphocele in the kidney graft.

Surgical Outcomes of Ipsilateral Inguinal Hernia After Kidney Transplantation.

OBJECTIVES: We aimed to clarify the clinical features and outcomes of ipsilateral inguinal hernias after kidney transplantation. PATIENTS AND METHODS: Eleven patients diagnosed with inguinal hernia on the ipsilateral side after kidney transplantation between 2011 and 2022 were analyzed. Clinical data were retrospectively reviewed from the medical records. RESULT: Eleven patients were included in the analysis (median age, 68 [range, 28-75] years, male, n = 11). The time from kidney transplantation to hernia surgery was 107 (6-393) months. Eight patients had direct-type inguinal hernias. Three had indirect-type inguinal hernias. Hernia contents included the small intestine (n = 5), transplanted ureter and bladder (n = 2), only bladder (n = 1), transplanted kidney, ureter, and small intestine (n = 1), transplanted kidney and small intestine (n = 1), and transplanted ureter (n = 1). Six patients (55%) were diagnosed with urinary tract obstruction due to inguinal hernia. All hernias were repaired using mesh. The plug method was used in 9 cases. The Lichtenstein method was used in 2 cases. The median operative time was 110 (73-155) minutes, and the median blood loss was 3 (1-85) mL. The median postoperative hospital stay was 4 (2-7) days. In the 6 patients with urinary obstruction, the serum creatinine levels improved (P = .028), and the transplanted urinary tract obstruction disappeared after surgery. There was no recurrence of inguinal hernia. One patient experienced chronic pain in the groin area (Clavien-Dindo grade II) during follow-up. CONCLUSION: Surgical intervention for inguinal hernia after kidney transplantation is safe and effective for preventing worsening of the kidney graft function.

Rapid detection of human cytomegalovirus UL97 and UL54 mutations for antiviral resistance in clinical specimens.

Drug-resistant cytomegalovirus appears during prolonged anti-cytomegalovirus therapy. Assays for human cytomegalovirus viral protein kinase (UL97) and viral DNA polymerase (UL54) gene mutations conferring drug resistance have been used rather than susceptibility assays to assess clinical specimens. In this study a sensitive system for genotype assay of UL97 and UL54 in clinical specimens with as few as six copies/µg of DNA was developed.

Profiling of kidney vascular endothelial cell plasma membrane proteins by liquid chromatography-tandem mass spectrometry.

BACKGROUND: Vascular endothelial cells (VECs) play crucial roles in physiological and pathologic conditions in tissues and organs. Most of these roles are related to VEC plasma membrane proteins. In the kidney, VECs are closely associated with structures and functions; however, plasma membrane proteins in kidney VECs remain to be fully elucidated. METHODS: Rat kidneys were perfused with cationic colloidal silica nanoparticles (CCSN) to label the VEC plasma membrane. The CCSN-labeled plasma membrane fraction was collected by gradient ultracentrifugation. The VEC plasma membrane or whole-kidney lysate proteins were separated by sodium dodecyl sulfate polyacrylamide gel electrophoresis and digested with trypsin in gels for liquid chromatography-tandem mass spectrometry. Enrichment analysis was then performed. RESULTS: The VEC plasma membrane proteins were purified by the CCSN method with high yield (approximately 20 µg from 1 g of rat kidney). By Mascot search, 582 proteins were identified in the VEC plasma membrane fraction, and 1,205 proteins were identified in the kidney lysate. In addition to 16 VEC marker proteins such as integrin beta-1 and intercellular adhesion molecule-2 (ICAM-2), 8 novel proteins such as Deltex 3-like protein and phosphatidylinositol binding clathrin assembly protein (PICALM) were identified. As expected, many key functions of plasma membranes in general and of endothelial cells in particular (i.e., leukocyte adhesion) were significantly overrepresented in the proteome of CCSN-labeled kidney VEC fraction. CONCLUSIONS: The CCSN method is a reliable technique for isolation of VEC plasma membrane from the kidney, and proteomic analysis followed by bioinformatics revealed the characteristics of in vivo VECs in the kidney.

Retroperitoneoscopic donor nephrectomy with a gel-sealed hand-assist access device.

BACKGROUND: The hand-assisted technique enables the rapid extraction of the graft, shortening the warm ischemia time (WIT), and the retroperitoneoscopic approach is potentially associated with a less incidence of postoperative ileus in donor nephrectomy for living kidney transplantation. The aim of this study was to assess the efficacy and safety of retroperitoneoscopic donor nephrectomy with a gel-sealed hand-assist access device (GelPort), which is a wound sealing device that permits the access of the hand to the surgical field, free trocar site choice within it, and rapid conversion to open surgery if necessary, while preserving the pneumoperitoneum/pneumoretroperitoneum. METHODS: Seventy-five consecutive donors receiving this procedure were retrospectively studied. A 2-cm skin incision was made at the midpoint between the tip of the 12th rib and superior border of the iliac bone in the midaxillary line, through which retroperitoneal space was made. Preperitoneal wound with a 6 - 7-cm pararectal incision in the upper abdominal region was connected to the retroperitoneal space. A GelPort was put inside the pararectal surgical wound. The principle was pure retroperitoneoscopic surgery; hand-assist was applied for retraction of the kidney in the renal vessel control and graft extraction. RESULTS: The mean operation time including waiting time for recipient preparation was 242.2±37.0 (range: 214.0-409.0) min, and the mean amount of blood loss was 164.3±146.6 (range: 10.0-1020.0) ml. The mean WIT was 2.8±1.0 (range: 1.0-6.0) min. The shortage of renal vessels or ureter was observed in none of the grafts. No donor experienced blood transfusion, open conversion, or injury of other organs. Blood loss was greater in patients with body mass index (BMI) of 25 kg/m2 or higher than in those with BMI of <25 kg/m2 (218.4±98.8 vs. 154.8±152.1 ml, P=0.031). No donor had postoperative ileus or reported wound pain leading to decreased activity of daily life or wound cosmetic problem. CONCLUSIONS: Retroperitoneoscopic hand-assisted donor nephrectomy with the mentioned approach was suggested to be a feasible option without compromising safety, although further improvement in surgical techniques is warranted.

Current Status of ABO-incompatible Liver Transplantation.

By 2014, strategies to prevent antibody-mediated rejection (AMR) after ABO-incompatible (ABO-I) living donor liver transplantation (LDLT) were established in Japan and expanded primarily to Asia, where LDLT is now the predominant form of LT owing to the scarcity of brain-dead donors. A desensitization protocol consisting of rituximab (375 mg/m 2 ), plasma pheresis, tacrolimus, and mycophenolate mofetil before LDLT, followed by standard immunosuppression, is currently the best option in terms of safety and efficacy. Rituximab administration is now known not to increase the risk of hepatocellular carcinoma recurrence, and the feasibility of rituximab for LDLT for acute liver failure and the need for desensitization before LDLT in children older than 1 y have been documented. Strategies are needed to distinguish patients at high risk of AMR from those at low risk and to adjust immunosuppression to prevent both AMR and infection. Specific single-nucleotide polymorphisms in genes encoding Fcγ receptors affecting the cytotoxicity of rituximab on B cells could be useful for adjusting immunosuppression levels to decrease infectious complications. Immunological accommodation after ABO-I transplantation could be provided by immune factors in both the grafts and recipients.

Pretransplant BMI Should Be <25 in Japanese Kidney Transplant Recipients: A Single-Center Experience.

BACKGROUND: The aim of this study was to determine the appropriate body mass index (BMI) in Japanese kidney transplant (KTx) recipients. We analyzed the effects of pre- and post-transplant (Tx) obesity on graft and patient survival, perioperative complications, post-transplant diabetes mellitus (PTDM), and cardiovascular disease (CVD) in Japanese KTx recipients. METHODS: This retrospective study included 269 recipients who underwent KTx from 2008 through 2020 at Niigata University Hospital. Obesity was defined as a body mass index (BMI) ≥25 kg/m2. We examined the association between pre- and post-Tx obesity and graft survival, patient survival, the incidence of PTDM and CVD, and perioperative surgical complications. RESULTS: The graft survival rate was lower in the pre-Tx BMI ≥25 kg/m2 group, although there was no significant difference in patient survival. There was no difference in graft and patient survival between the post-Tx BMI ≥25 kg/m2 group and the <25 kg/m2 group. A pre-Tx BMI ≥25 kg/m2 was an independent risk factor for biopsy-proven allograft rejection. New-onset DM after transplantation was significantly more common in the BMI ≥25 kg/m2 group than in the BMI <25 kg/m2 group (36% vs 13%; P = .002). The incidence of CVD was significantly higher in the post-Tx BMI ≥30 kg/m2 group than in the BMI <30 kg/m2 group (50% vs 11%; P = .023). There were no differences in surgical operating time, intraoperative blood loss, or perioperative complications between the obese and non-obese groups. CONCLUSION: Pre-Tx BMI ≥25 kg/m2 may be a risk factor for allograft rejection and graft loss. Post-Tx BMI should be <25 kg/m2 to reduce the risk for PTDM.

[PREGNANCIES IN KIDNEY TRANSPLANT RECIPIENTS, AN ANALYSIS OF 9 CASES].

(Objective) Pregnancy in kidney transplant recipient continues to remain challenging due to a high rate of cesarean section along with preterm delivery, and concern for worsening renal function. This study examined the prognosis and perinatal management of post-transplant pregnancies. (Patients and methods) A total of nine post-transplant recipients at Niigata University Medical and Dental Hospital between 2007 and 2021 were retrospectively examined. (Results) All pregnancies were planned. Calcineurin inhibitors and steroids were continued, and antimetabolites were changed to azathioprine. The mean age at delivery was 33±3.8 years, and the mean time from renal transplantation to delivery was 6.5±3.5 years. Five patients (55.5%) had cesarean sections, while four (44.5%) patients had normal vaginal deliveries. The mean gestational age was 35±3.0 weeks, and the mean birth weight was 2,336±565.4 g. No congenital malformation was observed. The most common reason for early delivery was worsening renal function, seen in six (66.7%) patients. The mean serum creatinine level before pregnancy was 1.11±0.23 mg/dL and then worsened to 1.59±0.37 mg/dL during pregnancy. However, it recovered to 1.14±0.40 mg/dL after delivery. One patient had antibody-mediated rejection with donor specific antibody (DSA) prior to pregnancy, and her renal graft function worsened slightly after delivery. Another patient had a de novo DSA after delivery, which was not detected before pregnancy. (Conclusions) In our hospital, pregnancy in kidney transplant recipients were safe and renal graft function after delivery was relatively stable. Patients may require adjustment of calcineurin inhibitors during pregnancy, and the appearance of DSA after delivery should be noted.

Long-term CMV monitoring and chronic rejection in renal transplant recipients.

Introduction: Cytomegalovirus (CMV) is well established to be an independent risk factor for graft loss after kidney transplantation (KTx). Monitoring for CMV in the chronic phase is not defined in the current guideline. The effects of CMV infection, including asymptomatic CMV viremia, in the chronic phase are unclear. Methods: We performed a single-center retrospective study to investigate incidence of CMV infection in the chronic phase, defined as more than 1 year after KTx. We included 205 patients who received KTx between April 2004 and December 2017. The CMV pp65 antigenemia assays to detect CMV viremia were continuously performed every 1-3 months. Results: The median duration of the follow-up was 80.6 (13.1-172.1) months. Asymptomatic CMV infection and CMV disease were observed in 30.7% and 2.9% in the chronic phase, respectively. We found that 10-20% of patients had CMV infections in each year after KTx which did not change over 10 years. The history of CMV infection in the early phase (within 1 year after KTx) and chronic rejection were significantly associated with CMV viremia in the chronic phase. CMV viremia in the chronic phase was significantly associated with graft loss. Discussion: This is the first study to examine the incidence of CMV viremia for 10 years post KTx. Preventing latent CMV infection may decrease chronic rejection and graft loss after KTx.