Sustained Epstein-Barr virus detection in paediatric liver transplantation. Insights into the occurrence of late PTLD

Screening and Management of PTLD

Posttransplant lymphoproliferative disorder (PTLD) represents a heterogeneous group of lymphoproliferative diseases occurring in the setting of immunosuppression following hematopoietic stem cells transplant and solid organ transplantation. Despite its overall low incidence, PTLD is a serious complication following transplantation, with a mortality rate as high as 50% in transplant recipients. Therefore, it is important to establish for each transplant recipient a personalized risk evaluation for the development of PTLD based on the determination of Epstein-Barr virus serostatus and viral load following the initiation of immunosuppression. Due to the dynamic progression of PTLD, reflected in the diverse pathological features, different therapeutic approaches have been used to treat this disorder. Moreover, new therapeutic strategies based on the administration of virus-specific cytotoxic T cells have been developed. In this review, we summarize the available data on screening and treatment to suggest a strategy to identify transplant recipients at a higher risk for PTLD development and to review the current therapeutic options for PTLD.

Post-transplant lymphoproliferative disorders, Epstein-Barr virus infection, and disease in solid organ transplantation: Guidelines from the American Society of Transplantation Infectious Diseases Community of Practice

PTLD with the response-dependent sequential use of RIS, rituximab, and cytotoxic chemotherapy is recommended. Evidence gaps requiring future research and alternate treatment strategies including immunotherapy are highlighted.

Risk factors and long-term outcomes of pediatric liver transplant recipients with chronic high Epstein-Barr virus loads

BACKGROUND

Serial monitoring of Epstein-Barr virus (EBV) reveals that certain pediatric liver transplant (LT) recipients exhibit high EBV loads for long periods. We investigated the incidence and risk factors of chronic high EBV (CHEBV) loads (continuous EBV DNA >10 000 IU/mL of whole blood for ≥6 months) and long-term outcomes.

METHODS

This single center, retrospective observational study investigated pediatric LT recipients who survived ≥6 months. We quantitated EBV DNA weekly during hospitalization and subsequently every 4 or 6 weeks at the outpatient clinic. Tacrolimus was maintained at a low trough level (<3 ng/mL, EBV DNA load >5000 IU/mL).

RESULTS

Thirty-one of 77 LT recipients developed CHEBV. Univariate analysis revealed that age <2 years and body weight <10 kg upon LT, operation time <700 minutes, warm ischemia time (WIT) >35 minutes, graft-to-recipient weight ratio (GRWR) >2.7%, and preoperative EBV seronegativity were significantly associated with the development of CHEBV loads. Multivariate analysis identified significant associations of CHEBV with WIT >35 minutes, GRWR >2.7%, and preoperative seronegative. None of the recipients developed post-transplantation lymphoproliferative disorder. Survival rates of patients with and without CHEBV loads were not significantly different.

CONCLUSIONS

A significant number of pediatric LT recipients developed CHEBV loads. Long WIT, high GRWR, and preoperative EBV seronegativity were significantly associated with the development of CHEBV loads. Although the long-term outcomes of patients with or without CHEBV loads were not significantly different, further studies of more subjects are warranted.

Seroprevalence of cytomegalovirus in donors & opportunistic viral infections in liver transplant recipients

Background & objectives:

Opportunistic virus infections are common in liver transplant (LT) recipients. There is a risk of developing infection with cytomegalovirus (CMV) and herpes-related viruses such as herpes simplex virus-1 and 2 (HSV-1 & 2), Epstein-Barr virus (EBV) and Varicella Zoster virus (VZV), reactivation of infection and recurrent infection. This study was conducted to determine CMV seropositivity in donors and its influence on LT recipients and seropositivity of CMV, HSV-1 and 2, EB viral capsid antigen (EBVCA) and VZV in LT recipients and their reactivation.

Methods:

Pre-transplant data for IgG and IgM for CMV (and donor), HSV-1 and -2, EB viral capsid antigen (VCA) and VZV were available for 153 recipients. All recipients were on ganciclovir or valganciclovir prophylaxis for three months after LT. For reactivation rates, findings of post-transplant CMV quantitative reverse transcription polymerase chain reaction (CMV qRT-PCR) assay were associated with pre-transplant serological profile.

Results:

Of the 153 LT recipients, 131 were men (85.6%). The median age of LT was 46 yr (range 9 months-71 yr). Overall exposure to CMV was 71.8 per cent followed by EB VCA (61.4%) and VZV (49.6%). Susceptibility to both HSV-1 and -2 was high across all decades (P<0.001). Seropositivity of CMV in donor was 90.9 per cent (100 out of 110). Post-transplant CMV qRT- PCR was positive in 17 (26.6%; 3 in recipient negative) of 64 samples tested. qRT-PCR assay was positive in one out of four (25%) tested for HSV-1 and nine out of 19 (47.4%) tested for EBV. Two recipients tested for HSV-2 and one for VZV were negative. There were three deaths in recipients (D+ R+) who were also positive for CMV qRT PCR. There was one death due to HSV-1 pneumonia. One patient with EBV reactivation developed post-transplant lymphoproliferative disorder two years after transplant.

Interpretation & conclusions:

Transplant recipient were at highest risk of acquiring HSV-1 and -2 more so for HSV-2. CMV exposure in transplant recipients and donors were very high and at greatest risk for recipient reactivation rate. Despite this, death related to CMV reactivation was low.

Peripheral Blood Epstein-Barr Viral Nucleic Acid Surveillance as a Marker for Posttransplant Cancer Risk

Several viruses, such as Epstein-Barr virus, are now known to be associated with several human cancers, but not all patients with these viral infections develop cancer. In transplantation, such viruses often have a prolonged time gap from infection to cancer development, and many are preceded by a period of circulating and detectable nucleic acids in the peripheral blood compartment. The interpretation of a viral load as a measure of posttransplant risk of developing cancer depends on the virus, the cancer and associated pathogenic factors. This review describes the current state of knowledge regarding the utility and limitations of peripheral blood nucleic acid testing for Epstein-Barr virus in surveillance and risk prediction for posttransplant lymphoproliferative disorders.

Persistent Epstein-Barr viral load in Epstein-Barr viral naïve pediatric heart transplant recipients: Risk of late-onset post-transplant lymphoproliferative disease

AIM

To examine the risk of late-onset post-transplant lymphoproliferative disorder (PTLD) in the presence of persisting high Epstein-Barr virus (EBV) in EBV naïve pediatric heart transplant (HT) recipients.

METHODS

A retrospective review of the medical records of the 145 pediatric HT recipients who had serial EBV viral load monitoring at our center was performed. We defined EBV naive patients whose EBV serology either IgM or IgG in the blood were negative at the time of HT and excluded passive transmission from mother to child in subjects less than 6 mo of age.

RESULTS

PTLD was diagnosed in 8 out of 145 patients (5.5%); 6/91 (6.5%) in those who were EBV seropositive and 2/54 (3.7%) in the EBV naïve group at the time of HT (P = 0.71). We found 32/145 (22%) patients with persistently high EBV load during continuing follow-up; 20/91 (22%) in EBV seropositive group vs 12/54 (22%) in EBV naïve group (P = 0.97). There was no significant association between pre-HT serostatus and EBV load after transplant (P > 0.05). In the EBV seropositive group, PTLD was diagnosed in 15% (3/20) of patients with high EBV vs 4.2% (3/71) of patients with low or undetectable EBV load (P = 0.14) whereas in EBV naïve patients 8.3% (1/12) of those with high EBV load and 2.3% (1/42) with low or undetectable EBV load (P = 0.41). There was a highly significant association between occurrence of PTLD in those with high EBV load and duration of follow up (4.3 ± 3.9 years) after HT by Cochran-Armitage test for the entire cohort (P = 0.005). At least one episode of acute rejection occurred in 72% (23/32) of patients with high EBV vs 36% (41/113) patients with low or undetectable EBV after HT (P < 0.05).

CONCLUSION

There is an association between persistently high EBV load during post-HT follow up and the occurrence of late-onset PTLD in pediatric HT recipients irrespective of serostatus at the time of transplant. The occurrence of allograft rejection increased in patients with high EBV load presumably due to reduction in immunosuppression.

Risk-adapted Treatment for Severe B-Lineage Posttransplant Lymphoproliferative Disease After Solid Organ Transplantation in Children

BACKGROUND

Optimal management of posttransplant lymphoproliferative disease (PTLD) remains to be defined due to heterogeneity of this condition and lack of predictors of the outcome. Here we report our experience with pediatric PTLD nonresponsive to immunosuppression (IS) withdrawal, managed after stratification into high and low risk according to the presenting features.

METHODS

This is a single-center retrospective review of prospectively enrolled patients. From 2001 to 2011, 17 children were diagnosed with severe B-lineage, CD20+, PTLD after a median of 37 months (range, 5-93) from liver (12), heart (4), or multiorgan (1) transplantation. Treatment was tailored on 2 risk groups: (1) standard-risk (SR) patients received IS reduction and rituximab; (2) high-risk (HR) patients received IS discontinuation, rituximab and polychemotherapy.

RESULTS

The cumulative incidence of rejection at 1 and 5 years after the diagnosis of PTLD was 35% (95% confidence interval [95% CI], 18-69%) and 53% (33-85%), respectively, whereas the disease-free survival at 1 and 5 years was 94% (95% CI, 65-99%) and 75% (45-90%), respectively. Three children died, PTLD-free, from different transplant-related complications: primary nonfunction after retransplantation (liver), cytomegalovirus disease 21 months after PTLD treatment (liver), graft dysfunction 25 months after PTLD (heart).

CONCLUSIONS

Severe B-lineage PTLD after solid organ transplantation may be classified as SR or HR and treated accordingly with a tailored protocol obtaining a satisfactory long-term outcome. This approach accomplishes the control of lymphoproliferation in severe forms as well as the minimization of toxicity in milder PTLDs.

Epstein-Barr virus-related post-transplant lymphoproliferative disorder in solid organ transplant recipients

Epstein-Barr virus (EBV) contributes to the pathogenesis of post-transplant lymphoproliferative disease (PTLD) in more than 70% of cases. EBV DNAemia surveillance has been reported to assist in the prevention and treatment of PTLD in hematopoietic stem-cell transplantation (HSCT) recipients. Derived from experience in HSCT and taking into account that PCR-based EBV monitoring techniques are currently available in most solid organ transplant (SOT) centres, there is a great interest in EBV surveillance and prevention of PTLD in SOT recipients. In the present document we have tried to address from a practical perspective different important topics regarding the prevention and management of EBV-related PTLD in SOT. To this end, available information on SOT was analysed and combined with potentially useful data from HSCT and expert observations. The document is therefore structured according to different specific questions, each of them culminating in a consensus opinion of the panel of European experts, grading the answers according to internationally recognized levels of evidence. The addressed issues were grouped under the following topics. (i) Timing and epidemiological data of PTLD. Prophylaxis guided by clinical risk factors of early and late PTLD in SOT. (ii) Relationship of EBV DNAemia load monitoring and the development of PTLD in solid organ transplant recipients. (iii) Monitoring of EBV DNAemia after SOT. Which population should be monitored? What is the optimal timing of the monitoring? (iv) Management of SOT recipients with persistent and/or increasing EBV DNAemia.

Viral surveillance and subclinical viral infection in pediatric kidney transplantation

The more potent immunosuppressive therapy that has successfully reduced the incidence of acute rejection and improved graft outcomes has also resulted in a higher incidence of viral complications. Sensitive molecular methods now allow for the detection of subclinical viral infection, which is increasingly recognized due to the adoption of routine post-transplant viral surveillance protocols. The goal of viral surveillance is the detection of subclinical viral infection that triggers an intervention; one that either prevents progression to viral disease or leads to early diagnosis of viral disease, which is associated with improved outcomes. Knowledge of the epidemiology and natural history of subclinical viral infection and viral disease, as well as patient-specific risk factors, is required to establish the optimal surveillance schedule which achieves the goal of early diagnosis. Evidence that detection of subclinical viral infection can impact viral disease is variable depending on the virus. This review will summarize the current data on the role of viral surveillance for BK virus (BKV), cytomegalovirus (CMV), and the Epstein-Barr virus (EBV) in the pediatric kidney transplant population.

Epstein-Barr viral load before a liver transplant in children with chronic liver disease

OBJECTIVES

Many children with chronic liver disease require a liver transplant. These patients are prone to various infections, including Epstein-Barr virus infection. This study sought to measure the Epstein-Barr viral load by polymerase chain reaction before a liver transplant.

MATERIALS AND METHODS

This cross-sectional study was done at the Shiraz University of Medical Sciences, Shiraz, Iran, in 2011. All patients were aged younger than 18 years with chronic liver disease and were candidates for a liver transplant at the Shiraz Nemazee Hospital Organ Transplant Center. They had been investigated regarding their demographic characteristics, underlying disease, laboratory findings, and Epstein-Barr viral load by real-time TaqMan polymerase chain reaction.

RESULTS

Ninety-eight patients were studied and the mean age was 6.5 ± 5.9 years. Cryptogenic cirrhosis was the most-prevalent reason for liver transplant, and the death rate before a transplant was 15%. Among the study subjects, 6 had measurable Epstein-Barr viral load by polymerase chain reaction before the transplant, and 4 of them had considerably higher Epstein-Barr viral loads (more than 1000 copies/mL).

CONCLUSIONS

With respect to the close prevalence of posttransplant lymphoproliferative disease (6%) and the high Epstein-Barr viral load in the patients before a transplant (4%), high pretransplant Epstein-Barr viral load can be considered a risk factor for posttransplant lymphoproliferative disorder.

Identifying predictive factors for posttransplant lymphoproliferative disease in pediatric solid organ transplant recipients with Epstein-Barr virus viremia

Epstein-Barr virus (EBV) viremia (EV) in pediatric solid organ transplant (SOT) recipients is a significant risk factor for posttransplant lymphoproliferative disease (PTLD) but not all patients with EV develop PTLD. We identify predictive factors for PTLD in patients with EV. We conducted a retrospective chart review of all pediatric SOT recipients (0 to 21 y) at a single institution between 2001 and 2009. A total of 350 pediatric patients received a SOT and 90 (25.7%) developed EV. Of EV patients, 28 (31%) developed PTLD. The median age at transplant was 11.5 months in the PTLD group and 21.5 months in the EV-only group (P=0.003). Twenty-three (37%) EV-only patients had immunosuppression increased before EV, compared with 28 (100%) of PTLD patients (P<0.001). The median peak EBV level was 3212 EBV copies/10 lymphocytes for EV-only and 8392.5 EBV copies/10 lymphocytes for PTLD (P=0.005). All patients who developed PTLD had ≥1 clinical symptoms. Younger age at transplant, increased immunosuppression before EV, higher peak EBV level, and presence of clinical symptoms have predictive value in the development of PTLD in SOT patients with EV.

Viral Diseases of the Liver

Viruses other than the classic hepatotropic viruses, hepatitis A through E, may cause hepatic injury [1]. Among these are Epstein–Barr virus (EBV), cytomegalovirus (CMV), herpes simplex virus (HSV), varicella zoster virus (VZV), human herpes viruses (HHV) 6, 7, and 8, human parvovirus B19, and adenoviruses (Table 11.1). The clinical presentation of infections with these viruses may be indistinguishable from that associated with infection with classic hepatotropic viruses. The presentation ranges from mild and transient elevation of aminotransferases to acute hepatitis and can also lead to acute liver failure [1]. These viruses should be considered as possible etiologic agents in patients who have acute liver injury and whose serologic markers for the classic hepatotropic viruses are not indicative of an active infection [1]. In the present chapter, we review the clinical manifestations and the potential for immune-mediated liver injury associated with several of these viruses (see summary Table 11.2).

Prevention and treatment for Epstein-Barr virus infection and related cancers

Epstein-Barr virus (EBV) was the first herpes virus described as being oncogenic in humans. EBV infection is implicated in post-transplant lymphoproliferative diseases (PTLD) and several other cancers in non-immunocompromised patients, with more than 200,000 new cases per year. While prevention of PTLD is improving, mainly based on EBV monitoring and preemptive tapering of immunosuppression, early diagnosis remains the best current option for the other malignancies. Significant progress has been achieved in treatment, with decreased mortality and morbidity, but some challenges are still to face, especially for the more aggressive diseases. Possible prevention by EBV vaccination would be a more global approach of this public health problem, but further active research is needed before this goal could be reached.

Effective control of Epstein-Barr virus infection following pediatric liver transplantation by monitoring of viral DNA load and lymphocyte surface markers

EBV-associated PTLD is a serious complication of liver transplantation. We performed periodical molecular EBV monitoring in 140 consecutive pediatric patients who had living-related liver transplantation in the National Center for Child Health and Development, Tokyo. Sixty-three of the 140 patients showed elevation of EBV DNA level to >10(2) copies/μg DNA and were further examined immunologically by flow cytometry, and the dose of tacrolimus and/or cyclosporine A was adjusted according to the results. The decrease in CD4/CD8 ratio and the increase in the number of HLA-DR(+) CD8(+) cells were observed in parallel with the decrease in EBV DNA load and in the number of CD19(+) CD23(+) cells following the reduction in immunosuppressive drugs. Analysis with HLA tetramers in a patient demonstrated a dramatic increase in the number of CD8(+) T cells specific to the EBV latent protein LMP2 accompanying the decline of EBV DNA load, suggesting that T cells of this specificity were actually involved in the control of EBV infection. No clinically apparent PTLD has developed in the 140 recipients, suggesting that our program of EBV control by molecular EBV monitoring coupled with lymphocyte phenotype analyses is effective in controlling EBV infection in pediatric liver transplant recipients.

Impact of immunosuppression on the development of Epstein-Barr virus (EBV) viremia after pediatric liver transplantation

OBJECTIVES

Pediatric liver transplant (OLT) patients are at risk of posttransplant lymphoproliferative disease (PTLD) from Epstein-Barr virus (EBV). This study examined the impact of induction and immunosuppression on EBV viremia.

METHODS

A retrospective chart review was performed on 197 pediatric patients and induction regimen, immunosuppression levels, and EBV viremia were documented for 1 year post-OLT. Logistic regression models determined associations between induction, immunosuppression, and EBV.

RESULTS

Fifty six percent of patients developed EBV viremia. Incidence of EBV viremia was 73% with antithymocyte globulin (ATG), 63% with daclizumab, and 39% for neither, though the trend was not significant [ATG: odds ratio (OR) 0.19; 95% confidence interval (CI) 0.024-1.58; P = .125; daclizumab OR; 1.07; 95% CI 0.270-4.23; P = .925]. Tacrolimus immunosuppression levels were supratherapeutic 28.7% of the time; however, only supratherapeutic tacrolimus levels between 0 and 2 weeks increased EBV viremia at 2 to 4 weeks post-OLT (OR 1.80; 95% CI 1.10-2.94; P = .02). Three patients developed PTLD.

CONCLUSIONS

The use of ATG and daclizumab induction likely does not play a role in the development of EBV viremia. Supratherapeutic tacrolimus levels 0 to 2 weeks post-OLT impact the development of EBV viremia at 2 to 4 weeks. The incidence of PTLD was low, suggesting better EBV and immunosuppression monitoring plays an important role in reducing PTLD.

Identification of Epstein–Barr virus-infected CD27+ memory B-cells in liver or stem cell transplant patients

To analyse the phenotype of Epstein–Barr virus (EBV)-infected lymphocytes in EBV-associated infections, cells from eight haematopoietic stem cell/liver transplantation recipients with elevated EBV viral loads were examined by a novel quantitative assay designed to identify EBV-infected cells by using a flow cytometric detection of fluorescent in situ hybridization (FISH) assay. By this assay, 0.05–0.78 % of peripheral blood lymphocytes tested positive for EBV, and the EBV-infected cells were CD20+ B-cells in all eight patients. Of the CD20+ EBV-infected lymphocytes, 48–83 % of cells tested IgD positive and 49–100 % of cells tested CD27 positive. Additionally, the number of EBV-infected cells assayed by using FISH was significantly correlated with the EBV-DNA load, as determined by real-time PCR (r 2 = 0.88, P<0.0001). The FISH assay enabled us to characterize EBV-infected cells and perform a quantitative analysis in patients with EBV infection after stem cell/liver transplantation.

Asymptomatic high Epstein-Barr viral load carriage in pediatric renal transplant recipients

High viral load carriage of EBV is one of the risks for PTLD in transplant recipients. We reviewed retrospectively in pediatric renal transplant recipients with EBV seronegative. EBV loads in peripheral blood and EBV-CTLs were measured every 1-3 months in 13 patients after grafting. Immunosuppressants were reduced when the patients were considered to have persistent high EBV loads (>1000 copies/μgDNA for over six months). All showed primary EBV infection: six with asymptomatic persistent high EBV loads (group A) and seven with neither EBV-associated symptoms nor persistent high EBV loads (group B). No patient developed PTLD in either group. Chronic rejection occurred in one patient in group A after immunosuppressants' reduction. There was no difference in renal dysfunction rates between the two groups. The maximum and increase rates in EBV loads were significantly higher in group A. The CTLs' percentage was significantly lower in group A when EBV loads first rose above 100 copies/μg DNA. This study suggests the possibility that EBV loads and CTLs' monitoring may be useful for avoidance of PTLD, as patients with asymptomatic persistent high EBV loads had higher EBV loads and lower percentages of CTLs.

Epstein-Barr virus: Silent companion or causative agent of chronic liver disease?

The Epstein-Barr virus (EBV) has an important and multifaceted role in liver pathology. As a member of the herpes virus family, EBV establishes a persistent infection in more than 90% of adults. Besides acute hepatitis during primary infection, many clinical syndromes of interest for the hepatologist are associated with EBV infection. The role of EBV in the evolution of chronic hepatitis from hepatotropic viruses is considered. Chronic EBV-associated hepatitis is suspected in immunocompetent adults with compatible serology, suggestive histology and detection of the viral genome in the liver and/or increase of specific circulating cytotoxic T-lymphocytes. EBV is the main cause of post-transplant lymphoproliferative disorders which occur in up to 30% of cases. EBV-driven lymphoproliferative diseases are also recognized in non-immunocompromised patients and liver is involved in up to a third of the cases. Directly implicated in the pathogenesis of different tumors, EBV has a disputable role in hepatocellular carcinoma carcinogenesis. Further research is required in order to establish or reject the role of EBV in human liver cancer. This paper attempts to discuss the range of EBV-associated chronic liver diseases in immunocompetent patients, from mild, self-limiting mononuclear hepatitis to liver cancer.

Using Epstein-Barr viral load assays to diagnose, monitor, and prevent posttransplant lymphoproliferative disorder

Epstein-Barr virus (EBV) DNA measurement is being incorporated into routine medical practice to help diagnose, monitor, and predict posttransplant lymphoproliferative disorder (PTLD) in immunocompromised graft recipients. PTLD is an aggressive neoplasm that almost always harbors EBV DNA within the neoplastic lymphocytes, and it is often fatal if not recognized and treated promptly. Validated protocols, commercial reagents, and automated instruments facilitate implementation of EBV load assays by real-time PCR. When applied to either whole blood or plasma, EBV DNA levels reflect clinical status with respect to EBV-related neoplasia. While many healthy transplant recipients have low viral loads, high EBV loads are strongly associated with current or impending PTLD. Complementary laboratory assays as well as histopathologic examination of lesional tissue help in interpreting modest elevations in viral load. Circulating EBV levels in serial samples reflect changes in tumor burden and represent an effective, noninvasive tool for monitoring the efficacy of therapy. In high-risk patients, serial testing permits early clinical intervention to prevent progression toward frank PTLD. Restoring T cell immunity against EBV is a major strategy for overcoming PTLD, and novel EBV-directed therapies are being explored to thwart virus-driven neoplasia.

Efficacy and safety of valganciclovir in liver-transplanted children infected with Epstein-Barr virus

Epstein-Barr virus (EBV) infection after liver transplantation (LT) is associated with increased risk of posttransplant lymphoproliferative disorder (PTLD). Lowering immunosuppression is the current method to prevent PTLD in LT children with a high viral load. The aim of this study was to assess the efficacy and safety of valganciclovir (VGCV) in children with EBV infection after LT. Forty-seven children showing detectable EBV-DNA (72% asymptomatic) were treated with VGCV (520 mg/sqm twice daily) with no immunosuppression decrease (except in 4 cases). VGCV treatment started 17 months (median) after the onset of EBV infection. A 30-day treatment applied to 26 patients led to undetectable EBV-DNA in 11/32 courses (34.3%), with 82% relapsing. A long VGCV treatment (median: 8 months) achieved undetectable EBV-DNA in 20/42 (47.6%), 60% of whom maintained response off therapy. There were no new PTLD cases. Symptoms worsened in 1 (2.1%) in whom PTLD was suspected but not confirmed in liver and jejunum biopsies. Factors associated with achievement of undetectable EBV-DNA were a longer time from LT and a lower rate of intervening infections in comparison with nonresponders. The safety profile for VGCV was excellent. Graft rejection occurred in 6%. In conclusion, in 47 LT children with a sustained increased EBV load treated with VGCV and unchanged immunosuppression, PTLD was suspected in 1 child (2.1%). A viral load decrease could be achieved as EBV-DNA was undetectable in 47% of patients under prolonged treatment.

Laboratory assays for Epstein-Barr virus-related disease

Epstein-Barr virus (EBV) infects various cell types in a wide spectrum of benign and malignant diseases. Laboratory tests for EBV have improved and are increasingly used in diagnosis, prognosis, prediction, and prevention of diseases ranging from infectious mononucleosis to selected subtypes of lymphoma, sarcoma, and carcinoma. Indeed, the presence of EBV is among the most effective tumor markers supporting clinical management of cancer patients. In biopsies, localization of EBER transcripts by in situ hybridization remains the gold standard for identifying latent infection. Other RNA- and protein-based assays detect lytic viral replication and can distinguish carcinoma-derived from lymphocyte-derived EBV in saliva or nasopharyngeal brushings. Analysis of blood using EBV viral load and serology reflects disease status and risk of progression. This review summarizes prior research in the context of basic virologic principles to provide a rational strategy for applying and interpreting EBV tests in various clinical settings. Such assays have been incorporated into standard clinical practice in selected settings such as diagnosis of primary infection and management of patients with immune dysfunction or nasopharyngeal carcinoma. As novel therapies are developed that target virus-infected cells or overcome the adverse effects of infection, laboratory testing becomes even more critical for determining when intervention is appropriate and the extent to which it has succeeded.

Failure of immunosuppressive drug levels to predict T-cell reactivity in pediatric transplant patients

PURPOSE

In children, therapeutic management of immunosuppression relies on allograft function, drug levels, and clinical insight. Using a Food and Drug Administration-approved test for T-cell response, T-cell activation in vitro can be measured to monitor the immune response.

METHODS

In a retrospective study, 92 posttransplant children who received either a liver and/or kidney transplant and were followed by routine screening had their T-cell response tested by the Cylex ImmuKnow assay (Columbia, MD). After phytohemagglutinin-L stimulation of T-cells, adenosine triphosphate (ATP) concentrations were measured. In this assay, light emission at lambda = 562 nm is proportional to the ATP concentration (ng/mL). Immunosuppressive drug trough levels were also measured. Quantitative real-time polymerase chain reaction Epstein-Barr virus (EBV) viral titers were determined for 2 patients.

RESULTS

Separating the results into younger than 12 years and 12-year or older populations, we found that for the younger than 12 years, 28% of patients were in the low immune function category, 47% in the moderate, and 25% in the high category. For the 12 years or older, 25% of patients were in the low immune function category, 47% in the moderate, and 28% in the high category. The immune function distribution was not different (P = not significant) between the younger than 12 years and 12-year or older groups. Tacrolimus trough levels were 6.3 +/- 2.4 ng/mL for younger than 12 years and 5.6 +/- 3.3 ng/mL for 12 years or older (P = not significant), and rapamycin was similar, but both showed no correlation to immune function. We observed increased ATP values with decreased EBV viral loads.

CONCLUSIONS

These results suggest that tacrolimus and/or rapamycin levels do not adequately determine the biologic effect of immunosuppression. We expect that future T-cell activation monitoring will allow us to diminish rejection and infection events posttransplantation and lead to a healthier pediatric transplant population.