Quantitation of Epstein-Barr virus DNA in the blood of adult liver transplant recipients

Effects of Epstein-Barr virus infection on the development of multiple myeloma after liver transplantation

Reduced cellular immune function in patients after liver transplantation easily results in many types of viral infections, such as Epstein-Barr virus. Epstein-Barr virus is a Γ-herpesvirus and is related to many malignant diseases, especially epithelial and lymph tumors. The abnormal interaction of cluster of differentiation 40 with cluster of differentiation 40 ligand and expression of cluster of differentiation 40 ligand are considered closely related to the development of myeloma cells. This study explored the influence and mechanism of Epstein-Barr virus infection on the phenotype and biological behavior of myeloma cells after liver transplantation. Flow cytometry was used to detect coexpression of cluster of differentiation 40 and cluster of differentiation 40 ligand in 10 samples of freshly isolated multiple myeloma cells. Cluster of differentiation 40 and cluster of differentiation 40 ligand were coexpressed in sample Nos. 5, 8, 9, and 10, particularly in sample No. 5. Western blot analysis was used to detect the expression of the Epstein-Barr virus antigens latent membrane protein 1 and Epstein-Barr virus nuclear antigen 2 in the multiple myeloma cell line RPMI 8226 infected with Epstein-Barr virus. The antigen expression indicated that Epstein-Barr virus can infect multiple myeloma virus cells in vitro. Reverse transcription-polymerase chain reaction revealed upregulated expression of cluster of differentiation 40 ligand on the infected RPMI 8226 cells, which may be involved in the anti-apoptosis activity of the infected cells. Confocal microscopy showed that pairs of molecules of cluster of differentiation 40, cluster of differentiation 40 ligand, and latent membrane protein 1 were colocalized on the surface of the infected cells. CXC chemokine receptor 4 was upregulated on the RPMI 8226 cells after Epstein-Barr virus infection. The migratory ability of the infected cells improved in the presence of the chemokine stromal cell-derived factor-1α. Anti-apoptosis and migration are known important biological characteristics of malignant cells. Our results indicate the involvement of Epstein-Barr virus in the origin and development of multiple myeloma. The risk of multiple myeloma increases when Epstein-Barr virus infects B cells in the germinal center, which may result in an anti-apoptosis effect of B cells and an improved ability to migrate from the germinal center to peripheral blood.

Significance of Epstein-Barr virus (EBV) load and Interleukin-10 in post-transplant lymphoproliferative disorders

The complex relationship between EBV, IL-10 and lymphomagenesis has been widely investigated and several studies have highlighted the diagnostic value of EBV DNA copies and serum IL-10, that may be considered as tumor markers. Notwithstanding the great number of data published in the last few years on the behavior of EBV DNA copies in the peripheral blood of transplanted patients, a threshold value significant for impending or overt post-transplant lymphoproliferative disorder (PTLD) has not yet been defined. Too many factors, both technical and clinicopathological, may affect the results of clinical studies, making their comparison difficult. On the contrary, although the role of IL-10 in PTLDs has been well documented, a sufficient number of studies exploring sensitivity and specificity of serum IL-10 measurement is lacking. The aim of this review is to summarise data on EBV load quantification and serum IL-10 detection in transplanted patients, providing clinicians with wide and useful information in order to improve bedside management of transplanted patients with regard to PTLDs occurrence and treatment.

Epstein-Barr virus load in whole blood is associated with immunosuppression, but not with post-transplant lymphoproliferative disease in stable adult heart transplant patients

Development of Epstein-Barr virus (EBV)-associated post-transplant lymphoproliferative disease (PTLD) is a serious complication following heart transplantation (HTX). This study investigates EBV DNA load in adult heart transplant recipients, its association with immunosuppression, and its potential as a marker for development of PTLD. EBV DNA load was measured prospectively by quantitative real-time polymerase chain reaction (PCR) in 172 stable HTX patients. Sixty-seven patients (39.0% of total) had a positive EBV PCR at initial examination [median 4.9 (range 1.1-16.9) years post-HTX]. In follow-up testing of 67 positive patients 6 months later, 36 patients continued to have a positive EBV PCR. Overall incidence of EBV DNA was significantly associated with calcineurin inihibitors, azathioprine medication, and with the absence of mycophenolate mofetil (MMF) treatment. In patients with positive EBV DNA levels at initial examination and negative levels at retesting, cyclosporine A levels were found to be significantly higher at initial examination (148.4 +/- 70.2 vs. 119.6 +/- 53.5 ng/ml, P < 0.05). Three patients (1.7%, 3/172) were diagnosed with PTLD during the course of the study (mean follow up 4.0 years). EBV DNA viral load determination does not appear to be useful for risk prediction or early diagnosis of PTLD in adults after HTX, but an association of EBV DNA load with qualitative and quantitative immunosuppression is demonstrated.

Post-transplant lymphoproliferative disease in liver transplantation

Post-transplant lymphoproliferative disease (PTLD) is a well recognized complication of solid organ transplantation and therapeutic immunosuppression, first reported in 1968. PTLD incorporates a spectrum of abnormalities ranging from a benign infectious mononucleosis-like illness to non-Hodgkin's lymphoma with nodal and extranodal site involvement. The first liver transplant was performed at our institution in January 1982. This retrospective study examined the incidence of PTLD, reason for the original transplants, presenting symptoms, radiological findings, immunosuppression regimens and outcomes of these patients. From a total of 2005 adult liver transplants, 23 patients (1.1%) were identified with PTLD. The average age of these patients at the time of transplant was 46.5 years, with a ratio of female-to-male of 14:9. Indication for transplant ranged from primary biliary cirrhosis (eight patients) to epitheloid haemangioendothelioma (one patient). The average time interval between transplant and diagnosis of PTLD was 50 months. Imaging abnormalities identified included generalized lymphadenopathy, liver and portal masses, splenic enlargement, bowel, eye, cerebral and neck involvement; and in two patients, no radiological abnormality. The most common histological findings ranged from B-cell non-Hodgkin's lymphoma (five patients) to early PTLD in one patient. Our rate of PTLD is lower compared with published literature and demonstrates a much longer time interval from transplant to occurrence of PTLD than previously appreciated. This could be secondary to a low immunosuppression therapy followed at our institution. From a few months to several years after liver transplantation, the radiologist needs to be alert to the possibility of PTLD and thorough imaging is required to detect the wide variety of potential presentations.

Epstein-Barr virus-related primary central nervous system lymphoma after cadaveric renal transplantation improved by treatment with high-dose methotrexate followed by irradiation

A 57-year-old man was admitted to hospital because of motor aphasia on 16 September 2000. He had an approximate 2-year history of haemodialysis treatment, since April 1997, and had received a cadaveric renal transplantation in July 1999. Computed tomography and magnetic resonance imaging (MRI) revealed a mass with ringed enhancement in the left temporal-parietal lobe. Primary central nervous system (CNS) lymphoma (diffuse large B cell type) was diagnosed based on an open brain tumour biopsy. Epstein-Barr virus early RNA (EBER) in situ hybridization showed positive signals in the nuclei of the CNS lymphoma cells. A dose reduction of immunosuppressant and three series of high-dose methotrexate (MTX) therapy with leucovorine rescue followed by irradiation (whole brain irradiation, 30 Gy; partial brain tumour irradiation, 20 Gy) were carried out for his primary CNS lymphoma. The patient is currently in good condition (September 2004) with no enlargement of the lymphoma, as examined by MRI every 3 months, and preserved renal function.

OKT3 and ganciclovir treatments are possibly related to the presence of Epstein-Barr virus in serum after liver transplantation

The development of Epstein-Barr virus (EBV) associated lymphoproliferative disorder (PTLD) is related to EBV genome numbers in serum or plasma and B-cells, and the level of immunosuppression. EBV DNA viremia, defined as presence of EBV genomes in serum or plasma, is common in immunodeficiency. This survey of EBV viremia was performed by real-time polymerase chain reaction (PCR) on consecutive serum samples of 21 patients with acute (n = 3) or chronic liver disease (n = 18) during the first year after liver transplantation (LTX). Cytomegalovirus (CMV) DNA was analyzed with PCR in serum or leukocytes. The levels of EBV and CMV viremia were related to PTLD and the effect of different anti-rejection regimens. All patients were EBV-seropositive pre-LTX. In total, 24 of 152 (16%) samples from 10 of 21 (48%) individuals were EBV positive [five of 11 cyclosporin A (CsA); five of 10 tacrolimus treated cases]. EBV viremia was demonstrated in five of seven patients with OKT3 therapy. The number of EBV DNA positive samples was highest (26%) at 14 days after LTX. In the OKT3 treated groups, the medians of EBV DNA copy numbers were 1600/ml (range 230-7200) and 380/ml (range 120-860) in the CsA and tacrolimus patients, respectively (P < 0.02). One patient developed EBV lymphoma and another one EBV hepatitis 13 months and 24 days post-LTX, respectively. Both patients had received OKT3. Their EBV genome load was not significantly different from what was found in other patients. After ganciclovir therapy, EBV DNA was eradicated from serum in four of five patients for several months. EBV DNA load was not affected by CMV infection or disease. We conclude that presence of EBV in serum is a possible marker of an active infection and an early ganciclovir therapy may be beneficial. Quantification of EBV load offers the potential to implement pre-emptive interventions.

Dynamic EBV gene loads in renal, hepatic, and cardiothoracic transplant recipients as determined by real-time PCR light cycler

BACKGROUND

Epstein-Barr virus (EBV) is recognised as one of the causative agents for most cases of post-transplant lymphoproliferative disease (PTLD). Elevated levels of EBV DNA are known to be associated with the onset of PTLD, but little information is available regarding how EBV loads change with time in asymptomatic transplant recipients following transplantation. Our aims were to study the trend of EBV loads in renal (RTx), hepatic, and cardiothoracic transplant recipients and to compare their EBV loads with other healthy and patient controls.

METHODS

A prospective study was performed using a real-time TaqMan polymerase chain reaction technique to measure EBV DNA loads from three types of organ transplant recipients and haemodialysis patients (HD). Their results were then compared with those from the healthy controls (HC); monospot test negative (MN-) and infectious mononucleosis positive (IM+) patients; patients who were previously treated for PTLD (pPTLD); those who were currently diagnosed to have PTLD (PTLD+); and patients who had a stable renal, hepatic, or cardiothoracic graft for more than a year.

RESULTS

Post-transplant EBV loads were significantly higher than the pre-transplant levels. Asymptomatic transplant recipients were differentiated from the PTLD+group at 600 genome copies of EBV/mug DNA, and from IM+group at 100 genome copies. Both HC and MN- groups had significantly lower EBV loads than the three transplant groups. The dynamic change of EBV loads in RTx was greater in the first post-transplant month when compared with the HD group. All transplant recipients had transient rises of EBV loads whereas EBV load continued to rise in one suspected PTLD patient.

CONCLUSIONS

Asymptomatic transplant recipients had higher baseline post-transplant EBV levels than the non-transplant and MN- groups. The rising post-transplant EBV load in these transplant recipients did not seem to be sustained for longer than 2 weeks. However, in a PTLD+patient the rising EBV load continued over a period of 4 weeks. Hence, the dynamic pattern of EBV loads is more important than absolute EBV DNA measurements alone in identifying those who might go on to develop PTLD.

Assessment of automated DNA extraction coupled with real-time PCR for measuring Epstein-Barr virus load in whole blood, peripheral mononuclear cells and plasma

BACKGROUND

Epstein-Barr virus (EBV) DNA load monitoring in blood has been shown to be essential for the diagnosis of EBV-associated diseases. However, the methods currently used to assess EBV DNA load are often time-consuming and require prior blood separation.

OBJECTIVES

The aim of this study was to evaluate the relative diagnostic value of EBV DNA load monitoring in whole blood, peripheral blood mononuclear cells (PBMCs) and plasma after automated DNA extraction using the MagNA Pure extractor followed by LightCycler real-time quantitative PCR (LC-PCR).

STUDY DESIGN

First, EBV DNA load was assessed retrospectively after automated or manual extraction on 104 PBMC specimens. Second, EBV DNA load was determined prospectively with the automated extraction procedure in the whole blood, PBMCs and plasma of 100 samples from patients with EBV-related diseases (group 1, n = 20), HIV-seropositive individuals (group 2, n = 66), and healthy EBV carriers (group 3, n = 14).

RESULTS

A good correlation was observed between automated and manual extraction on 104 PBMC specimens (r = 0.956; P < 0.0001). In the prospective study, 67 samples were positive in both whole blood and PBMCs, with a good correlation between EBV DNA loads in whole blood and PBMCs (r = 0.936; P < 0.0001). Only 18/100 samples were positive in plasma. Higher viral loads were regularly observed in the three blood compartments from group 1 than from groups 2 and 3.

CONCLUSION

This study demonstrated that an automated extraction of EBV DNA is easier to perform in whole blood or plasma than in PBMCs and facilitates the standardisation of EBV DNA measurement by real-time quantitative PCR. The quantitative detection of EBV DNA load in whole blood appeared more sensitive than in plasma for infectious mononucleosis in immunocompetent patients, probably because of a rapid loss of plasmatic EBV DNA. In transplant patients, EBV DNA load monitoring in whole blood and in plasma turned out to be equivalent in terms of feasibility and accuracy for the early diagnosis of post-transplant lymphoproliferative diseases (PTLDs).

RELATIONSHIP BETWEEN CD8+ T-CELL PHENOTYPE AND FUNCTION, EPSTEIN-BARR VIRUS LOAD, AND CLINICAL OUTCOME IN PEDIATRIC RENAL TRANSPLANT RECIPIENTS: A PROSPECTIVE STUDY1

BACKGROUND

The authors studied the relationship between the dynamics of Epstein-Barr virus (EBV) load, CD8 T-cell activation and differentiation, and EBV-associated symptoms in 25 children after kidney transplantation (Tx).

METHODS

Twenty-two patients were enrolled at the time of Tx and three at diagnosis of EBV-induced post-transplant lymphoproliferative disease (PTLD). EBV load was serially measured by a semiquantitative method of DNA amplification in blood cells. The percentages of activated (human leukocyte antigen-DR) and of effector-memory (CD28) CD8 circulating cytolytic T lymphocytes (CTL) were serially evaluated by flow cytometry. The cytotoxic potential of CTL was assessed by a CD3-redirected cytotoxic assay.

RESULTS

For three children with post-Tx uncomplicated primary EBV infection, EBV load peaked by months 1 to 2 after Tx and declined spontaneously by months 3 to 6, whereas expansion of activated and effector-memory CTL was absent (one case) or transient and moderate (two cases). In 15 patients who were EBV-seropositive before Tx and who did not develop EBV-PTLD, transient elevation of EBV load but no noticeable changes in CTL phenotype were observed. In contrast, in one child who was also EBV-seropositive before Tx but who developed EBV-PTLD, a major and sustained elevation of EBV load and of activated and effector-memory CTL was observed. In three patients retrospectively enrolled at diagnosis of EBV-PTLD, sustained elevation of both viral load and activated T cells was also noticed. Finally, increased cytotoxic activity correlated with increased level of activated CTL.

CONCLUSIONS

An association between high and sustained T-cell activation, EBV load, and the occurrence of EBV-PTLD was observed. Furthermore, intense cytotoxic activity was observed in EBV-PTLD, with favorable outcome.

Use of real-time PCR to measure Epstein-Barr virus genomes in whole blood

The measurement of the Epstein-Barr viral load in peripheral blood has been recognised as an important way of monitoring the response to treatment in patients with Epstein-Barr virus (EBV)-related malignancies. In particular, EBV load in transplant recipients can be used as a predictive parameter for Post-transplant Lymphoproliferative Disorder (PTLD). The aim was to develop a rapid and reliable PCR protocol for the quantification of the cell-associated EBV genome. Real-time PCR using TaqMan methodology was established. This technique was applied to determine the EBV load in various study groups including healthy controls, transplant recipients, patients on haemodialysis, and patients with infectious mononucleosis. The baseline level of EBV genomes in the immunosuppressed renal transplant recipients was significantly different from that in the healthy controls.

Longitudinal analysis of Epstein-Barr viral load in plasma and peripheral blood mononuclear cells of transplanted patients by real-time polymerase chain reaction

BACKGROUND

Posttransplant lymphoproliferative disease (PTLD) is a significant cause of morbidity and mortality in transplant recipients and is caused by iatrogenic suppression of T cell function. Elevations in the Epstein-Barr viral (EBV) load in plasma (>1000 EBV copies/100 microL plasma) or peripheral blood mononuclear cells (PBMC) (>5000 EBV copies/microg PBMC DNA) as determined by real-time quantitative polymerase chain reaction (RQ-PCR) have been shown to be sensitive indicators for the development of PTLD in patients.

METHODS

The diagnostic value of frequent monitoring of EB viral load in peripheral blood from 46 patients after heart transplantation was investigated compared with 21 healthy controls in a prospective longitudinal study. EB viral load was detected in PBMC and plasma using real-time quantitative (RQ)- polymerase chain reaction (PCR)-based assays and compared with serological parameters of EBV infection or with the occurrence of CMV reactivations.

RESULTS

EB viral load was significantly increased in PBMC and in plasma from transplanted patients compared with healthy controls. Regarding levels and fluctuations of EB viral load in PBMC, patients were grouped in three distinct categories with high, intermediate, or low EB viral load. Although in one patient without PTLD, the EB viral load exceeded the threshold value for PTLD of 5000 EBV copies/microg PBMC DNA, all patients had an EB viral load in plasma of less than 1000 EBV copies/100 microL plasma. No correlation was found between the level of EB viral load and serological parameters of EBV reactivations in patients or in healthy control individuals. EBV and cytomegalovirus reactivations occurred independently in the majority of patients.

CONCLUSIONS

EB viral load measurements in plasma and PBMC of patients using RQ-PCR are superior to serology and are a powerful tool for monitoring transplanted patients.

Epstein-Barr viral load as a tool to diagnose and monitor post-transplant lymphoproliferative disease

Epstein-Barr virus (EBV)-induced post-transplant lymphoproliferative disease (PTLD) continues to be a rare but severe complication following transplantation. EBV viral load is used as a tool to identify patients at risk for developing PTLD. However, studies on EBV viral load are hard to compare since study design as well as EBV detection method and calculation of results are highly variable. In the majority of cases EBV viral load is increased in patients with PTLD compared to patients without disease. There is, however, some overlap. Some individual patients with only low viral load show PTLD while others show the opposite. The major future goals will be to standardize EBV-DNA detection in order to generate comparable data in different centers and to establish cut-off values to distinguish patients with PTLD from patients without with a high precision.

Significance of serial real-time PCR monitoring of EBV genome load in living donor liver transplantation

BACKGROUND

Quantitative analysis of the Epstein-Barr virus (EBV) genome has been recently reported to be helpful for early identification of EBV viremia which could reduce the risk of post-transplantation lymphoproliferative disorder (PTLD).

AIM

To demonstrate the significance of serial monitoring of EBV genome load by real-time quantitative polymerase chain reaction (PCR) after living donor liver transplantation.

METHODS

From March 1999 to April 2000, the EBV genome load in peripheral blood mononuclear cells (PBMNC) was measured serially in a total of 15 recipients of living donor liver transplantation (LDLT) who had a symptomatic EBV infection.

RESULTS

In 15 patients, the mean values of the highest EBV DNA levels from the patients who had fever, URS, diarrhea, ascites, lymphadenopathy and PTLD were 36 232, 16 040, 15 968, 2485, 336 858 and 60 486 copies/microg DNA, respectively. Patients were treated by reduction or discontinuation of immunosuppressives and/or antiviral agents. The EBV DNA levels decreased in all these patients following the recovery from their symptoms. We encountered two cases of PTLD during this study period. One of them was referred to us after the onset of PTLD and one had been undergoing aggressive immunosuppression treatment for severe rejection. Both were successfully treated.

CONCLUSIONS

Serial quantitative analysis of the EBV genome load by means of real-time PCR are thought to be useful for preventing PTLD through adjustment of the immunosuppression level in response to the viral genome load following symptomatic EBV infection.

Role of Epstein-Barr virus DNA load monitoring in prevention and early detection of post-transplant lymphoproliferative disease

Posttransplant lymphoproliferative disease (PTLD) is a severe and life-threatening complication after stem cell or solid-organ transplantation, virtually always associated with presence of Epstein-Barr virus (EBV) in the proliferating cells. PTLD is probably caused by the iatrogenically impaired T-cell response allowing outgrowth of EBV-positive B-cells. Quantitative EBV DNA load monitoring is a minimally invasive technique increasingly recognized as a valuable tool in posttransplant patient management. In this review, we focus on the clinical utility of EBV DNA load monitoring in the peripheral blood of transplant recipients using PCR and we discuss the currently most-widely used techniques and their value and limitations in predicting and diagnosing PTLD. Options for EBV DNA load-guided pre-emptive therapy and application of monitoring EBV DNA load dynamics in the prediction of clinical response after therapy are described. Origins of elevated EBV DNA loads in immunosuppressed patients and recent insights in the EBV life cycle in the immuncompromised host are discussed. Finally, a standardization of methodology, clinical specimen type, and cut-off values is proposed. This is essential for comparisons between different institutes and more adequate patient management.

Epstein-Barr virus (EBV) DNA in sera of patients with primary EBV infection

Detection of Epstein-Barr Virus (EBV) DNA by PCR in serum had a sensitivity of 80%, a specificity of 94%, and positive and negative predictive values of 95 and 79%, respectively, for the diagnosis of primary EBV infection. We suggest that this is a useful addition to the panel of tests used for this purpose.

Evaluation of use of Epstein-Barr viral load in patients after allogeneic stem cell transplantation to diagnose and monitor posttransplant lymphoproliferative disease

Epstein-Barr virus (EBV)-induced posttransplant lymphoproliferative disease (PTLD) continues to be a serious complication following transplantation. The aim of the present study was to evaluate the EBV load as a parameter for the prediction and monitoring of PTLD. The EBV load was analyzed by a quantitative competitive PCR with 417 whole-blood samples of 59 patients after allogeneic stem cell transplantation (SCT). The EBV load was positive for all 9 patients with PTLD and for 17 patients without PTLD. The viral loads of patients with manifest PTLD differed from the loads of those without PTLD (median loads, 1.4 x 10(6) versus 4 x 10(4) copies/microg of DNA; P < 0.0001). A threshold value of 10(5) copies/microg of DNA showed the best diagnostic efficacy (sensitivity, 87%; specificity, 91%). However, in patients with less than three major risk factors for PTLD, the positive predictive value of this threshold was rather low. One week prior to the manifestation of PTLD, the EBV load was as low in patients who developed PTLD as in patients without disease (median, 2.2 x 10(4) copies/microg of DNA; P was not significant). EBV DNA tested positive first at 20 to 71 days prior to the clinical manifestation of PTLD and occurred with the same delay after transplantation regardless of disease (median delay, 52 versus 63 days; P was not significant). EBV DNA was detected earlier in patients with primary infections than in those with reactivations (33 versus 79 days; P = 0.01), but the peak levels were similar in the two groups. EBV primary infection or EBV reactivation is frequent in patients after allogeneic SCT but results in PTLD only in a subgroup of patients. Although evaluation of the EBV load has limitations, the EBV load represents a valuable parameter to guide therapy.

Epstein-Barr virus (EBV) DNA in sera of patients with primary EBV infection

Detection of Epstein-Barr Virus (EBV) DNA by PCR in serum had a sensitivity of 80%, a specificity of 94%, and positive and negative predictive values of 95 and 79%, respectively, for the diagnosis of primary EBV infection. We suggest that this is a useful addition to the panel of tests used for this purpose.

Patients at risk for development of posttransplant lymphoproliferative disorder: plasma versus peripheral blood mononuclear cells as material for quantification of Epstein-Barr viral load by using real-time quantitative polymerase chain reaction

BACKGROUND

Early diagnosis of Epstein-Barr virus (EBV)-associated posttransplant lymphoproliferative disorder (PTLD) is required to detect a stage of disease that is more likely to respond to treatment. Elevated levels of EBV DNA were found in peripheral blood of patients at the onset of PTLD.

METHODS

To compare plasma and peripheral blood mononuclear cells (PBMCs) as material for real-time quantitative polymerase chain reaction (RQ-PCR) measurement of Epstein-Barr viral load, we used two sets of primers and probes specific for the BAM HI-K or BAM HI-W region of the EBV genome.

RESULTS

Patients with PTLD had a median viral load of 19,200 EBV genomes/microg DNA (n=9) or 3,225 EBV genomes/100 microl plasma (n=5), being significantly higher compared with immunosuppressed patients with primary (n=9) or reactivated (n=20) EBV infection or immunosuppressed patients without serological signs of active EBV infection (n=67) (P<0.001). Hence, a value of greater than 5,000 EBV genomes/microg PBMC DNA was considered as a diagnostic parameter for PTLD with a sensitivity and specificity of 1.00 or 0.89, respectively. When plasma was analyzed, however, a value of greater than 1,000 EBV genomes/100 microl plasma had both a sensitivity and specificity of 1.00 for the diagnosis of PTLD. During remission of PTLD, viral load was more effectively cleared in plasma compared with PBMCs. In plasma of nonimmunosuppressed individuals, even a qualitative detection of EBV-related sequences was sensitive and specific for the diagnosis of primary EBV infection, whereas for analysis of PBMC DNA a quantitative parameter had to be considered to differentiate healthy individuals (< 100 EBV genomes/microg PBMC DNA) from patients with primary EBV infection (>100 EBV genomes/microg PBMC DNA).

CONCLUSION

Although both PBMCs and plasma were useful as material for EBV-specific RQ-PCR in immunosuppressed patients and nonimmunosuppressed individuals, the specificity of analysis seemed to be higher if plasma was taken for analysis.

Diagnostic testing in Epstein-Barr virus infection

Laboratory diagnosis of Epstein-Barr virus (EBV) infection is improving with the development of new technologies. Quantification of the virus by real-time polymerase chain reaction (PCR) and evaluation of EBV-specific T cells, especially by tetrameric human leukocyte antigens, are noteworthy candidates for monitoring procedures in clinical laboratories involved in the management of transplant recipients. Standardization of PCR is essential for improving the quality of these monitoring procedures.

Epstein-Barr virus infection in paediatric liver transplant recipients: detection of the virus in post-transplant tonsillectomy specimens

AIMS

Post-transplant lymphoproliferative disease (PTLD) is an important and serious complication in transplant patients. Recent studies have suggested that quantitative assessment of Epstein-Barr virus (EBV) infection in transplant patients might help to identify those at risk of developing PTLD. Therefore, tonsils from paediatric liver transplant recipients were studied for evidence of EBV infection.

METHODS

Tonsils were studied by in situ hybridisation for the detection of the small EBV encoded nuclear RNAs (EBERs). The phenotype of EBV infected cells was determined by double labelling in situ hybridisation and immunohistochemistry. The expression of viral latent and lytic antigens was determined by immunohistochemistry. Tonsils from patients without known immune defects were studied as controls.

RESULTS

Tonsils from transplant patients showed pronounced follicular hyperplasia and minor paracortical hyperplasia. In situ hybridisation revealed variable numbers of EBV infected B cells in the tonsils from transplant patients (range, 2-1000/0.5 cm(2); mean, 434/0.5 cm(2); median, 105/0.5 cm(2)). Lower numbers were detected in the control tonsils (range, 1-200/0.5 cm(2); mean, 47/0.5 cm(2); median, 9/0.5 cm(2)). The latent membrane protein 1 (LMP1) of EBV was not detected and there were only rare cells in two cases showing expression of the EBV encoded nuclear antigen 2 (EBNA2). There was no evidence of lytic infection. None of the patients developed PTLD within a follow up period of up to five years.

CONCLUSIONS

These data indicate that tonsillar enlargement in paediatric liver transplant patients does not necessarily imply a diagnosis of PTLD. Furthermore, the presence of increased numbers of EBV infected cells in tonsils from liver transplant recipients by itself does not indicate an increased risk of developing PTLD.

Epstein-Barr virus load monitoring: its role in the prevention and management of post-transplant lymphoproliferative disease

The Epstein-Barr virus load in the peripheral blood at the time of diagnosis of post-transplant lymphoproliferative disease (PTLD) is elevated 1000- to 10,000-fold compared to the level detected in normal latency. With the use of quantitative polymerase chain reaction (PCR), changes in the viral load over time can be measured with a two- to fourfold accuracy. This has allowed early detection of first-time infections and reactivations that may lead to PTLD and has provided an opportunity to intervene before symptomatic disease has occurred. Viral load monitoring has also been used to follow patients with PTLD and, along with other parameters, provided an assessment of the effectiveness of therapeutic protocols. Viral load monitoring has led to the discovery that at least two-thirds of transplant recipients become persistent viral load carriers. While the persistent load appears to be largely carried in latently infected memory B cells, more work is needed to clearly define this type of persistent infection and determine the risks associated with it. New diagnostic tests need to be developed to distinguish the persistent latent viral loads from viral loads that are likely to become symptomatic PTLD.