Quantification of a low cellular immune response to aid in identification of pediatric liver transplant recipients at high-risk for EBV infection.

OBJECTIVE: Uncontrolled EBV infection leading to lymphoproliferative disease is a significant cause of morbidity in pediatric orthotopic liver transplant (OLT) recipients. Herein, we describe the use of a novel immune assay, which quantifies the lymphocyte immune response and correlates the value to risk for EBV infection. METHODS: All patient data were prospectively collected between 2003 and 2005. The study included 18 pediatric liver transplant recipients, seven males and 11 females with a mean follow-up of 47 months post-OLT. Patient EBV load was monitored using real-time quantitative PCR (qPCR). The ATP release (ng/mL) of CD3+ lymphocytes after mitogenic stimulation with phytohemagluttinin (PHA; Cylex Corporation) was used to quantitate patient immune response. Patients were stratified by EBV load: low (<1000 copies/microg DNA), medium (1000-4000 copies/microg DNA), and high (>4000 copies/microg DNA). RESULTS: Patients with low EBV loads had a significantly (p < 0.04) stronger immune response to PHA than patients with EBV load >1000 copies/microg DNA. Further analysis demonstrated that patients with ATP level <125 ng/mL had 100% probability of an EBV titer >4000 copies/microg DNA, when compared with 22% if the ATP level was between 125 and 400 ng/mL or only 15% if >400 ng/mL (p < 0.05). When immunosuppression was reduced, we observed an increase of the ATP release that correlated with a decrease of the EBV viral load. CONCLUSION: In conclusion, this study investigates the use of a lymphocyte activation assay to closely measure the immunosuppression status of pediatric liver transplant recipients. Because measurement of EBV DNA load as a single parameter has a poor positive predictive value for development of PTLD, the association of these assays may be of help in the identification of patients at risk for PTLD.

Hepatitis C viral recurrence in a pediatric patient following liver transplantation.

Hepatitis C virus (HCV) infections are known to have a more benign course in children than in adults. Although the natural history of HCV recurrence after liver transplantation has been well studied in adult patients, much less is known about HCV recurrence after liver transplantation in pediatric patients. Herein, we report a case of a pediatric patient with HCV presumably acquired through vertical transmission. She underwent liver transplantation at 14 yr of age. The first three yr after liver transplantation were uneventful. However, in the past 12 months she has been hospitalized twice after developing ascites, hematemesis and esophagogastroduodenoscopy (EGD)-documented esophageal varices. Post-transplant biopsy has demonstrated chronic inflammation complicated with active hepatitis C and stage 2-3 scarring. This case report demonstrates the need for further epidemiologic studies to study the natural history of the rate of HCV recurrence after liver transplantation in the pediatric population.

Use of cytokine polymorphisms and Epstein-Barr virus viral load to predict development of post-transplant lymphoproliferative disorder in paediatric liver transplant recipients.

OBJECTIVE: Currently there are no tests to accurately identify paediatric liver transplant patients at risk for post-transplant lymphoproliferative disorder (PTLD). Herein we describe the use of cytokine polymorphisms and real-time quantitative polymerase chain reaction (qPCR) Epstein-Barr virus (EBV) viral load to identify patients at risk for PTLD development. METHODS: Between 2001 and 2004, approximately 1047 patient samples were collected for qPCR for EBV in 59 patients. EBV viral load was reported in three groups: low EBV (<4,000 copies/microg DNA), high EBV/no PTLD (>4000 copies/microg DNA) and biopsy-proven PTLD. All 59 patients also had cytokine polymorphism genotyping performed for six cytokine polymorphisms (transforming growth factor (TGF)-beta, tumor necrosis factor (TNF)-alpha, interleukins (IL)-6, IL-10, IL-2, and interferon (IFN)-gamma) from DNA isolated from peripheral blood mononuclear cells. Positive predictive value (PPV) and negative predictive value (NPV) were calculated using qPCR and cytokine polymorphism results. Data are reported as a mean +/- standard error of the mean. RESULTS: There were 35 males and 24 females with a mean follow-up of 34.9 months. EBV viral load had a PPV and NPV of 29 and 95%, respectively. The low IFN-gamma (A/A) polymorphism was found to be present in 4/6 PTLD patients (67%) and only 17/53 (33%) non-PTLD patients. When the low A/A IFN-gamma polymorphism was combined with EBV viral load for prediction of PTLD, PPV and NPV were 57 and 93%, respectively. DISCUSSION: Use of cytokine genotyping in conjunction with qPCR for EBV viral load can significantly improve the predictive value of diagnostic tests for identification of patients at high risk for PTLD.

Quantitative EBV viral loads and immunosuppression alterations can decrease PTLD incidence in pediatric liver transplant recipients.

Epstein-Barr virus (EBV) is a common viral infection in pediatric liver transplant patients and can lead to development of post-transplant lymphoproliferative disorder (PTLD). Differing studies have used immunosuppression reduction, antiviral medications or i.v. CMV-immunogloublin for EBV prevention and treatment. The purpose of this study was to determine whether implementation of a protocol for frequent EBV monitoring and EBV viral load-driven immunosuppression reduction could decrease the incidence of PTLD in our patient population. All data were prospectively collected between 2001 and 2004 at a single institution. Seventy-three patients were entered into the study. Patients were divided into a historical control group (pre-2001, 30 patients) and a treatment group (post-2001, 43 patients). Approximately 1271 blood samples of 73 patients were collected between 2001 and 2004. Eleven out of 43 patients received immunosuppression tapering due to high EBV viral loads (>4000 copies/microg DNA). One patient developed allograft rejection after immunosuppression modulation. Prior to 2001, the incidence of PTLD at our institution was 16%. After instituting a protocol for EBV monitoring, the incidence of PTLD decreased to 2% (p-value<0.05). These findings illustrate that frequent EBV viral load monitoring and preemptive immunosuppression modulation have an integral role in preventing PTLD in the pediatric liver transplant population.

Split-liver transplantation using the left lateral segment: a collaborative sharing experience between two distant centers.

Split-liver transplantation (SLT) increases the pool of organs for pediatric orthotopic liver transplantation (pOLT). With increased collaboration and organ sharing, transplant centers can fully maximize the use of all split donor allografts. Herein, we report the collaborative results between two distant centers involved in a sharing alliance. The current study consists of a retrospective review of 56 pediatric LLS transplants performed at two collaborating centers between 9/1997 and 10/2003. Fifty-three patients (41% Status 1) were transplanted using 56 left lateral segment (LLS) grafts. Sixteen percent of LLS grafts were shared between the two institutions. Overall patient survival at both 1 and 3 years was 90% and 90%, respectively. Overall graft survival at both 1 and 3 years was 82% and 82%, respectively. Shared patient and graft survival was 89% and 89%, respectively. There was an 11% biliary complication and 18% vascular complication rate. Five patients required retransplantation. In conclusion, SLT increases the number of available allografts for pOLT. While SLT is technically demanding, with a significant learning curve, patient and graft survival rates compare favorably with United Network Organ Sharing (UNOS) averages. Sharing of grafts between centers is a safe and effective way to maximize organ usage and should be actively pursued through collaborative networks.

Intravenous Cidofovir therapy for disseminated adenovirus in a pediatric liver transplant recipient.

BACKGROUND: No definitive antiviral therapy exists for adenovirus (ADV) in immunosuppressed hosts. Cidofovir (CDV), a broad spectrum anti-DNA viral agent, has previously been shown to be of therapeutic benefit in life-threatening adenoviral disease in bone marrow stem-cell recipients. METHODS: A 71/2-month-old girl with a history of biliary atresia developed fevers, hematochezia, tachypnea, and laboratory evidence of hepatitis and pancreatitis 12 days after liver transplantation. A stool culture, oropharyngeal culture, blood viral culture, and blood polymerase chain reaction (PCR) confirmed ADV. Cidofovir 1 mg/kg intravenously three times per week was initiated. The patient received intravenous hydration and probenecid with the infusions to reduce the nephrotoxicity of CDV. Immunosuppression was reduced to achieve tacrolimus trough levels of approximately 8 ng/mL and prednisone at 0.1 mg/kg per day. Complete blood cell count, urinalysis, and viral studies were obtained weekly. RESULTS: Detection of ADV DNA by PCR made a transition from positive to negative during CDV therapy. Blood viral cultures became negative after two CDV doses. Alanine aminotransferase normalized by 5 weeks of therapy. CDV was discontinued after 7 weeks secondary to transient acidosis and proteinuria. The patient never developed azotemia, neutropenia, or ocular abnormalities. CONCLUSIONS: CDV was associated with improved clinical status, viral clearance, and minimal transient side effects in a pediatric liver transplant recipient with disseminated adenoviral disease. The current report documents clearance of disseminated ADV infection in a liver transplant recipient receiving CDV infusions.