Epstein-Barr virus in inflammatory diseases of the liver and liver allografts: an in situ hybridization study

What is expected from the pathologist in the diagnosis of viral hepatitis?

The clinician expects from the pathologist a clinically relevant diagnosis on the basis of liver biopsy interpretation. Today, a liver biopsy, as invasive procedure, is only justified when a significant benefit for the patient can be expected particularly with respect to the clinical management. Consequently, liver biopsy is usually not required in uncomplicated acute viral hepatitis. It is, however, an important diagnostic tool in chronic hepatitis and in transplanted liver to confirm the clinical diagnosis and to assess stage and grade of necroinflammation, treatment efficiency, and concurrent diseases. The diagnosis of liver disease is based on teamwork between clinician and pathologist. Evaluation of the biopsy in the clinical context requires clinical information and appropriate size and handling of the biopsy specimen. Aim of this review is the discussion of morphologic features of acute and chronic viral hepatitis with regard to their clinical relevance.

Epstein-Barr virus latency in kidney specimens from transplant recipients

BACKGROUND

Epstein-Barr virus (EBV) infection is common in immunosuppressed patients and can lead to life threatening lymphoproliferative diseases. Small numbers of cells infected by EBV have been detected in human tissues, transplanted or non-transplanted. Little is known about EBV latency in the allograft kidneys of patients without post-transplant lymphoproliferative disease (PTLD). The aims of this study were to look for the presence of EBV-encoded small RNAs (EBER) in allograft kidneys and to quantify their expression.

METHODS

We analysed 62 allograft nephrectomies and 20 native kidneys to determine the presence of EBV; we also quantified its expression and calculated its ratios to CD45 and CD20 cells. The techniques used were: tissue microarray, EBER-1- and 2-specific in situ hybridization and immunohistochemistry.

RESULTS

EBER expression was detected in 30.6% of transplanted kidneys and 5% of non-transplanted kidneys. In the positive specimens, a mean of 8.2 cells/1.57 mm(2) expressed the EBERs (range 1-38 cells). The ratios of EBER-positive (+) cells to CD45 or CD20 cells were 1.7 +/- 2.4% (range 0.1-8.1%) and 8.4 +/- 10.9% (range 0.5-34.4%), respectively. No relationship was found between anti-T-cell treatment and EBER expression in the failed allografts.

CONCLUSIONS

In failed kidney allografts, a small number of lymphocytes can express EBV latency. The number of EBER+ cells is smaller than in PTLD. Studies of functioning grafts are necessary to better understand the clinical relevance of this expression.

Late hepatic allograft dysfunction

1. Lifelong monitoring of graft function, immunosuppressive levels, and screening for drug toxicity is required in all liver recipients. 2. Late hepatic allograft dysfunction is common and is caused by a variety of etiologies including rejection, infection, biliary/vascular abnormalities, recurrence of disease, and drug hepatotoxicity. 3. In all patients with late hepatic allograft dysfunction, liver biopsy should be performed to assess for the presence of rejection, and to thus avoid excessive use of bolus corticosteroid therapy and guide appropriate immunosuppressive management. 4. Recurrence of disease is the most common cause of late hepatic allograft dysfunction. 5. Hepatitis C universally reinfects the hepatic allograft, and is associated with decreased patient and graft survival and leads to the recurrence of cirrhosis in 28% of patients within 5 years of transplantation. 6. Major advances have been made in preventing recurrence of hepatitis B by the use of hepatitis B immune globulin in combination with lamivudine therapy. 7. Autoimmune liver diseases such as primary biliary cirrhosis, primary sclerosing cholangitis, and autoimmune hepatitis have a recurrence rate of approximately 20% to 30%. 8. In patients developing recurrence of autoimmune hepatitis, steroid withdrawal is the most common cause. 9. Recurrent hepatocellular cancer can be markedly reduced if strict guidelines are adhered to in selecting patients. 10. Drug hepatotoxicity must always be considered in the differential diagnosis of late hepatic allograft dysfunction.

Epstein-Barr virus infection and human malignancies

The Epstein-Barr virus (EBV) is a herpes virus which establishes a life-long persistent infection in over 90% of the human adult population world-wide. Based on its association with a variety of lymphoid and epithelial malignancies, EBV has been classified as a group 1 carcinogen by the International Agency for Research on Cancer. In this article we discuss the evidence supporting an aetiological role for EBV in the pathogenesis of human tumours. The biology of EBV infection will be described with special emphasis on viral transforming gene products. A brief survey of EBV-associated tumours is followed by a discussion of specific problems. Evidence is presented which suggests that failures of the EBV-specific immunity may play a role in the pathogenesis of EBV-associated tumours also in patients without clinically manifest immunodeficiencies. Finally, the timing of EBV infection in the pathogenesis of virus-associated malignancies is discussed. There is good evidence that EBV infection precedes expansion of the malignant cell populations in some virus-associated tumours. However, this is clearly not always the case and for some of these tumours there are indications that clonal genetic alterations may occur prior to EBV infection. Thus, whilst there is good evidence to suggest that EBV is a human carcinogen, its precise role(s) in the development of virus-associated human tumours requires clarification.

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 infection and human malignancies

The Epstein-Barr virus (EBV) is a herpes virus which establishes a life-long persistent infection in over 90% of the human adult population world-wide. Based on its association with a variety of lymphoid and epithelial malignancies, EBV has been classified as a group 1 carcinogen by the International Agency for Research on Cancer. In this article we discuss the evidence supporting an aetiological role for EBV in the pathogenesis of human tumours. The biology of EBV infection will be described with special emphasis on viral transforming gene products. A brief survey of EBV-associated tumours is followed by a discussion of specific problems. Evidence is presented which suggests that failures of the EBV-specific immunity may play a role in the pathogenesis of EBV-associated tumours also in patients without clinically manifest immunodeficiencies. Finally, the timing of EBV infection in the pathogenesis of virus-associated malignancies is discussed. There is good evidence that EBV infection precedes expansion of the malignant cell populations in some virus-associated tumours. However, this is clearly not always the case and for some of these tumours there are indications that clonal genetic alterations may occur prior to EBV infection. Thus, whilst there is good evidence to suggest that EBV is a human carcinogen, its precise role(s) in the development of virus-associated human tumours requires clarification.

Epstein-Barr virus infection and human malignancies

The Epstein-Barr virus (EBV) is a herpes virus which establishes a life-long persistent infection in over 90% of the human adult population world-wide. Based on its association with a variety of lymphoid and epithelial malignancies, EBV has been classified as a group 1 carcinogen by the International Agency for Research on Cancer. In this article we discuss the evidence supporting an aetiological role for EBV in the pathogenesis of human tumours. The biology of EBV infection will be described with special emphasis on viral transforming gene products. A brief survey of EBV-associated tumours is followed by a discussion of specific problems. Evidence is presented which suggests that failures of the EBV-specific immunity may play a role in the pathogenesis of EBV-associated tumours also in patients without clinically manifest immunodeficiencies. Finally, the timing of EBV infection in the pathogenesis of virus-associated malignancies is discussed. There is good evidence that EBV infection precedes expansion of the malignant cell populations in some virus-associated tumours. However, this is clearly not always the case and for some of these tumours there are indications that clonal genetic alterations may occur prior to EBV infection. Thus, whilst there is good evidence to suggest that EBV is a human carcinogen, its precise role(s) in the development of virus-associated human tumours requires clarification.

Identifying the patient at risk for post-transplant lymphoproliferative disorder

Post-transplant lymphoproliferative disorders (PTLD) are a recognized complication of the immunosuppression required to prevent allograft rejection, occurring in 1-20% of recipients of solid organ transplants. Several factors greatly increase the risk of developing PTLD early post-transplant in any individual recipient. Epstein-Barr virus (EBV) infection is critical in the pathogenesis of the majority of these cases. Pre-transplant EBV seronegativity increases the incidence of PTLD 10- to 75-fold over that of EBV-seropositive recipients. Other risk factors include very young recipient age, cytomegalovirus infection or mismatching (donor positive-recipient negative), aggressive immunosuppression with conventional biologic agents, and the type of organ transplanted. In contrast, the risk of developing PTLD late in the post-transplant course does not appear to be influenced by the type of immunosuppressive agents employed, but rather by the duration of any immunosuppression. The role of EBV in late PTLD is also less certain, as a greater proportion of lesions are not associated with evidence of EBV infection. As the understanding of these risk factors has expanded, opportunities exist to target those populations at highest risk for the development of PTLD for aggressive monitoring and pre-emptive or prophylactic therapy. It is hoped that implementation of such strategies will render early PTLD a preventable complication of transplantation.

Allograft liver biopsy in patients with Epstein-Barr virus-associated posttransplant lymphoproliferative disease

Allograft liver biopsy specimens (n = 24) obtained in the clinical setting of primarily extrahepatic posttransplant lymphoproliferative disease (PTLD) were studied for histopathology, lymphocyte subsets, and Epstein-Barr virus (EBV)-encoded EBER RNA. Acute rejection was found in 20 (83.3%) of 24 biopsy specimens and graded as indeterminate in 7 (35%) of 20 (35%), mild in 3 (15%) of 20, and moderate in 10 (50%) of 20 cases. EBV hepatitis was the primary diagnosis in two biopsy specimens and a secondary finding in six others. Four biopsy specimens showed nonspecific reactive hepatitis, and five showed recurrence of primary liver disease. Immunoperoxidase staining showed primarily T cells. EBER RNA was detected in 14 (58.3%) of 24 biopsy specimens: 12 (60%) of 20 with and 2 (50%) of 4 without acute rejection. Antirejection therapy resulted in complete or partial response in 4 (36.3%) of 11 and 7 (63.7%) of 11 treated cases, respectively, despite the presence of EBV-infected cells in some tissues. Subsequent follow-up showed early or late chronic rejection in 6 (25%) of 24 patients. Gamma glutamyl transferase, a marker for early or late chronic rejection, was greater than five times the upper limit of normal in 9 (37.5%) of 24 patients. In conclusion, liver biopsy specimens in patients with PTLD show a spectrum of pathologic changes. Rejection may be treated even if EBV is concurrently present. Long-term graft is suboptimal, because low immunosuppression results in a tendency to develop chronic rejection.

Recommendations for the outpatient surveillance of renal transplant recipients. American Society of Transplantation

Many complications after renal transplantation can be prevented if they are detected early. Guidelines have been developed for the prevention of diseases in the general population, but there are no comprehensive guidelines for the prevention of diseases and complications after renal transplantation. Therefore, the Clinical Practice Guidelines Committee of the American Society of Transplantation developed these guidelines to help physicians and other health care workers provide optimal care for renal transplant recipients. The guidelines are also intended to indirectly help patients receive the access to care that they need to ensure long-term allograft survival, by attempting to systematically define what that care encompasses. The guidelines are applicable to all adult and pediatric renal transplant recipients, and they cover the outpatient screening for and prevention of diseases and complications that commonly occur after renal transplantation. They do not cover the diagnosis and treatment of diseases and complications after they become manifest, and they do not cover the pretransplant evaluation of renal transplant candidates. The guidelines are comprehensive, but they do not pretend to cover every aspect of care. As much as possible, the guidelines are evidence-based, and each recommendation has been given a subjective grade to indicate the strength of evidence that supports the recommendation. It is hoped that these guidelines will provide a framework for additional discussion and research that will improve the care of renal transplant recipients.

Epstein-Barr virus infections in children after transplantation of the small intestine

Epstein-Barr virus (EBV) infection in association with immunosuppressive drugs used for solid organ transplantation can produce a spectrum of illnesses. Forty-one children who ranged in age from 6 months to 18.5 years received small intestinal transplants alone or in combination with other organs while undergoing primary tacrolimus (FK506) immunosuppression between July 1990 and June 1995. We reviewed hematoxylin and eosin-stained sections from all biopsy, surgical, and autopsy material from these children to determine the incidence and morphology of EBV-associated disease. Nuclear staining with in situ hybridization for EBV early RNA transcript (EBER) using the EBER-1 probe confirmed the presence of EBV. The EBV lymphoproliferations were graded as 1 to 4 according to histopathology and EBV quantitation determined in the area of greatest positivity. Twenty-one patients (51%) had EBV documented histologically on one or more occasions; only 8 (38%) are alive; 5 of these had the highest grade of 2. Posttransplant lymphoproliferative disease (PTLD) developed in 13 patients. Three of 10 patients (30%) with grade 3 lesions (polymorphous PTLD) are alive with intermittent evidence of EBV infection; 6 died with PTLD. Monomorphic PTLD (grade 4) was the cause of death in the three additional patients. Thirteen of 20 patients (65%) with no histologic evidence of EBV are alive. The incidence of EBV infection in pediatric small intestinal transplant recipients is higher than reported for any other solid organ cohort. With the aid of frequent EBER staining we were able to diagnose EBV infections in 51% of 41 patients; PTLD (grade 3 or 4) developed in 32% of these children. Low-grade EBV infections often preceded the development of PTLD and were identified in gastrointestinal biopsy samples from patients with concurrent PTLD; however, results of gastrointestinal biopsy samples may be negative for EBV in some patients with PTLD and, thus, underestimate systemic EBV-associated lymphoproliferations. Rejection and EBV infection can occur simultaneously, therefore, attention to low-grade infection may be useful to patient management.

Epstein-Barr virus infection and malignant lymphomas in liver transplant recipients

Post-transplant lymphoproliferative disease (PTLD) is a major cause of death and disease in transplant patients. We describe 4 cases with histologically confirmed malignant lymphoma arising in the Birmingham liver transplant programme between 1982 and 1995. One was an EBV-positive diffuse large B-cell lymphoma, 2 were EBV-positive Burkitt's lymphomas and the 4th was an EBV-negative Burkitt's lymphoma. Immunohistochemistry revealed expression of the EBV-encoded latent membrane protein LMP1 and of the BZLF1 trans-activator protein in 2 cases each, whereas the virus-encoded nuclear antigen EBNA2 was not detectable. All available post-transplant biopsies from the 3 patients with EBV-associated lymphoma were then studied to test whether the detection of EBV-positive cells in liver allograft biopsies could be used to identify patients at risk for the development of PTLD. Two patients showed infrequent EBV-positive cells in liver allograft biopsies up to 14 months before the occurrence of lymphoma and a marked increase in the number of such cells at the time of lymphoma diagnosis. Multiple biopsies from the 3rd patient did not reveal any EBV-carrying cells in the entire post-transplant period. Our results demonstrate a low incidence of PTLD in the Birmingham liver transplant programme. The PTLDs were morphologically high-grade malignant lymphomas. Only 3 cases were associated with EBV infection, and these showed heterogeneous patterns of EBV latent protein expression. Our results also suggest that the examination of liver allograft biopsies using EBER in situ hybridisation is not an appropriate method for identifying patients at risk of developing PTLD.

Infections in solid-organ transplant recipients

Solid-organ transplantation is a therapeutic option for many human diseases. Infections are a major complication of solid-organ transplantation. All candidates should undergo a thorough infectious-disease screening prior to transplantation. There are three time frames, influenced by surgical factors, the level of immunosuppression, and environmental exposures, during which infections of specific types most frequently occur posttransplantation. Most infections during the first month are related to surgical complications. Opportunistic infections typically occur from the second to the sixth month. During the late posttransplant period (beyond 6 months), transplantation recipients suffer from the same infections seen in the general community. Opportunistic bacterial infections seen in transplant recipients include those caused by Legionella spp., Nocardia spp., Salmonella spp., and Listeria monocytogenes. Cytomegalovirus is the most common cause of viral infections. Herpes simplex virus, varicella-zoster virus, Epstein-Barr virus and others are also significant pathogens. Fungal infections, caused by both yeasts and mycelial fungi, are associated with the highest mortality rates. Mycobacterial, pneumocystis, and parasitic diseases may also occur.

Increased expression of proliferating cell nuclear antigen in liver allograft rejection

Detection of proliferating cell nuclear antigen is useful for the study of proliferative activity of neoplastic and non-neoplastic lymphoid, parenchymal, and mesenchymal cells. Allograft rejection is associated with the recruitment of circulating cells and their proliferation in the graft. The intrahepatic expression of proliferating cell nuclear antigen on paraffin-embedded liver biopsy specimens (n = 110 from 32 patients) was examined by an avidin-biotin peroxidase method using a monoclonal antibody to proliferating cell nuclear antigen. The percentage of positive nuclei was determined in hepatocytes, biliary epithelium, and lymphocytes. There were four histologic groups: 1, moderate-to-severe rejection (n = 19); 2, mild rejection (n = 28); 3, nonspecific inflammation (n = 45); and 4, donor livers (n = 18). The percentage of positive nuclei was higher in group 1 compared to group 2 (hepatocytes p = 0.01; biliary epithelium p = 0.0007; lymphocytes p = 0.0001), to group 3 (hepatocytes p = 0.0002; biliary epithelium p = 0.0001; lymphocytes p = 0.0001), and to group 4 (for all three locations p < 0.0001). When group 2 was compared to group 3 the results were significant for biliary epithelium (p = 0.0001) and lymphocytes (p = 0.0001), but not for hepatocytes (p = 0.07). We conclude that proliferating cell nuclear antigen expression, especially in lymphocytes, correlates with the severity of histologic rejection. Proliferating cell nuclear antigen expression may be useful in predicting the progression and response to different antirejection therapies.

Renal allograft involvement by Epstein-Barr virus associated post-transplant lymphoproliferative disease

This study describes nine cases of post-transplant lymphoproliferative disease (PTLD) presenting as renal allograft dysfunction. Onset of symptoms was 34 to 265 days post-transplant, typically (in six of nine cases) after refractory rejection treated with OKT3. Diagnosis was made by histopathologic examination of needle biopsy (three of nine cases) or allograft nephrectomy (six of nine cases) specimens. Disease was confined to the allograft in three patients. The morphology was polymorphic in eight cases and monomorphic in one case. Five cases showed monotypic kappa or lambda light chain expression. Expansile lymphoid infiltrates, serpiginous necrosis, nuclear atypia, and presence of Epstein-Barr virus RNA helped to distinguish PTLD from severe rejection. Tubular damage and venulitis was common in PTLD lesions, but arterial involvement was not prominent. Infiltration of the ureter, hilar adipose tissue, and nerve twigs was frequent in nephrectomy specimens. Reduction of immunosuppression led to resolution of PTLD in two of three cases diagnosed by needle biopsy, but severe acute rejection led to graft loss in one case; the third case progressed to fatal multisystem disease. Among cases diagnosed at nephrectomy, two of six patients died of disseminated PTLD and one of six died of sepsis. The five surviving patients are alive 41 to 99 months after initial diagnosis without evidence of recurrent PTLD.