The role of Epstein-Barr virus in the pathogenesis of Hodgkin's disease

Epstein-Barr Virus Latent Membrane Protein 2A (LMP2A) enhances IL-10 production through the activation of Bruton's tyrosine kinase and STAT3

Previous data demonstrate that Epstein-Barr Virus Latent Membrane Protein 2A (LMP2A) enhances IL-10 to promote the survival of LMP2A-expressing B cell lymphomas. Since STAT3 is an important regulator of IL-10 production, we hypothesized that LMP2A activates a signal transduction cascade that increases STAT3 phosphorylation to enhance IL-10. Using LMP2A-negative and -positive B cell lines, the data indicate that LMP2A requires the early signaling molecules of the Syk/RAS/PI3K pathway to increase IL-10. Additional studies indicate that the PI3K-regulated kinase, BTK, is responsible for phosphorylating STAT3, which ultimately mediates the LMP2A-dependent increase in IL-10. These data are the first to show that LMP2A signaling results in STAT3 phosphorylation in B cells through a PI3K/BTK-dependent pathway. With the use of BTK and STAT3 inhibitors to treat B cell lymphomas in clinical trials, these findings highlight the possibility of using new pharmaceutical approaches to treat EBV-associated lymphomas that express LMP2A.

An auto-regulatory loop for EBV LMP2A involves activation of Notch

LMP2A is consistently detected in Hodgkin's lymphoma, nasopharyngeal carcinoma and has also been detected in Burkitt's lymphoma. Interestingly, LMP2A is detected in the absence of the transcriptional activator EBNA2, suggesting that an alternative mechanism is responsible for LMP2A expression. The intracellular domain of Notch (Notch-IC) and EBNA2 are functional homologs and recent microarray analysis indicates that LMP2A may constitutively activate the Notch pathway in vivo. Coupled with evidence that Notch-IC can bind to and activate the LMP2A promoter, we hypothesized that expression of LMP2A results in the constitutive activation of the Notch pathway to auto-regulate its promoter. Our data indicate that LMP2A constitutively activates the Notch pathway in B cells and epithelial cells. Expression of LMP2A alone is sufficient to activate its own expression and the amino-terminal signaling domain is required as LMP2B is unable to activate the LMP2A promoter. In addition, point mutations in tyrosines 31, 101 and 112 each results in a significant decrease in LMP2A promoter activation. Deletion of the RBP-Jkappa consensus sequences results in a significant decrease in promoter activity. The observation that LMP2A activates its own promoter suggests that LMP2A exploits the Notch pathway in order to control its own expression and may explain EBNA2-independent expression of LMP2A in EBV-associated malignancies.

Fine-needle aspiration cytology of metastatic nasopharyngeal carcinoma

Cytological features of nasopharyngeal carcinoma (NPC) were reviewed in an attempt to select cytological criteria that permit a specific recognition of metastases. For this purpose, 54 fine-needle aspiration (FNA) procedures from 43 patients with NPC were analyzed. Thirty-two (59.3%) procedures were performed before the histological diagnosis. In 25 (46.3%) procedures, smears showed many neoplastic single cells, clusters, and abundant lymphoid cells (mixed pattern). A dissociated (single cell) pattern consisting of individual neoplastic and lymphoid cells was seen in 18 (33.3%) cases. Finally, 11 (20.4%) cases showed cohesive epithelial clusters (cohesive pattern) without relevant cellular dissociation or lymphoid cells. Squamous-cell differentiation was seen in three of these cases. Most single neoplastic cells presented as large, pleomorphic naked nuclei. Other interesting findings were granulomas (n = 3), prominent eosinophilic infiltrates (n = 4), and suppurative changes (n = 5). In most smears with mixed and dissociated patterns, a nasopharyngeal origin could be suggested. On the contrary, those smears with a cohesive pattern were indistinguishable from other head and neck carcinomas. The presence (on cervical lymph nodes) of a dissociated or mixed (single cells and groups) architectural pattern of large, anaplastic cells and naked nuclei accompanied by an abundant lymphoid component is highly suggestive of undifferentiated NPC. Cytology offers a rapid diagnosis, establishes the necessity of a complete cavum examination, and helps in avoiding unnecessary and harmful biopsies.

Epstein-Barr Virus (EBV) LMP2A induces alterations in gene transcription similar to those observed in Reed-Sternberg cells of Hodgkin lymphoma

Epstein-Barr virus (EBV) is associated with the development of a variety of malignancies, including Hodgkin lymphoma. One of the few viral transcripts expressed in EBV-positive Hodgkin/Reed-Sternberg (HRS) cells of Hodgkin lymphoma is latent membrane protein 2A (LMP2A). This viral protein blocks B-cell receptor (BCR)-signaling in vitro. Furthermore, expression of LMP2A in developing B cells in vivo induces a global down-regulation of genes necessary for proper B-cell development. In this study we have analyzed gene transcription in primary B cells from LMP2A transgenic mice, LMP2A-expressing human B-cell lines, and LMP2A-positive and -negative EBV-infected lymphoblastoid cell lines (LCLs). We demonstrate that LMP2A increases the expression of genes associated with cell cycle induction and inhibition of apoptosis, alters the expression of genes involved in DNA and RNA metabolism, and decreases the expression of B-cell-specific factors and genes associated with immunity. Furthermore, many alterations in gene expression induced by LMP2A are similar to those recently described in HRS cells of Hodgkin lymphoma and activated, proliferating germinal center centroblasts/centrocytes. These correlations suggest that LMP2A expression in EBV-infected B cells may lead to the induction and maintenance of an activated, proliferative state that could ultimately result in the development of Hodgkin lymphoma.

Epstein-Barr virus LMP2A interferes with global transcription factor regulation when expressed during B-lymphocyte development

Epstein-Barr virus (EBV) is associated with the development of malignant lymphomas and lymphoproliferative disorders in immunocompromised individuals. The LMP2A protein of EBV is thought to play a central role in this process by allowing the virus to persist in latently infected B lymphocytes. We have demonstrated that LMP2A, when expressed in B cells of transgenic mice, allows normal B-cell developmental checkpoints to be bypassed. To identify cellular genes targeted by LMP2A that are involved in this process, we have utilized DNA microarrays to compare gene transcription in B cells from wild-type versus LMP2A transgenic mice. In B cells from LMP2A transgenic mice, we observed decreased expression of many genes associated with normal B-cell development as well as reduced levels of the transcription factors that regulate their expression. In particular, expression of the transcription factor E2A was down-regulated in bone marrow and splenic B cells. Furthermore, E2A activity was inhibited in these cells as determined by decreased DNA binding and reduced expression of its target genes, including the transcription factors early B-cell factor and Pax-5. Expression of two E2A inhibitors, Id2 and SCL, was up-regulated in splenic B cells expressing LMP2A, suggesting a possible mechanism for E2A inhibition. These results indicate that LMP2A deregulates transcription factor expression and activity in developing B cells, and this likely allows for a bypass of normal signaling events required for proper B-cell development. The ability of LMP2A to interfere with B-cell transcription factor regulation has important implications regarding its role in EBV latency.

In vivo effects of the Epstein-Barr virus small RNA EBER-1 on protein synthesis and cell growth regulation

Recent studies have suggested a role for the Epstein-Barr virus-encoded RNA EBER-1 in malignant transformation. EBER-1 inhibits the activity of the protein kinase PKR, an inhibitor of protein synthesis with tumour suppressor properties. In human 293 cells and murine embryonic fibroblasts, transient expression of EBER-1 promoted total protein synthesis and enhanced the expression of cotransfected reporter genes. However reporter gene expression was stimulated equally well in cells from control and PKR knockout mice. NIH 3T3 cells stably expressing EBER-1 exhibited a greatly increased frequency of colony formation in soft agar, and protein synthesis in these cells was relatively resistant to inhibition by the calcium ionophore A23187. Nevertheless clones containing a high concentration of EBER-1 were not invariably tumourigenic. We conclude that EBER-1 can enhance protein synthesis by a PKR-independent mechanism and that, although this RNA may contribute to the oncogenic potential of Epstein-Barr virus, its expression is not always sufficient for malignant transformation.

Overview of the role of molecular methods in the diagnosis of malignant lymphomas

OBJECTIVE

To review the role of molecular genetics in the diagnosis of malignant lymphomas.

DATA SOURCES AND STUDY SELECTION

Primary research studies and reviews published in the English literature that focus on molecular genetics and malignant lymphoma, in particular, clonality, chromosomal translocations, tumor suppressor genes, and Hodgkin disease.

DATA EXTRACTION AND SYNTHESIS

Molecular genetics has an important role in the assessment of malignant lymphomas. Clonality, detected by Southern blot analysis or the polymerase chain reaction, is helpful for establishing the diagnosis of lymphoma in lesions with ambiguous morphologic and immunophenotypic findings. Southern blot analysis is the "gold standard" for clonality assessment, but the process is labor-intensive and time-consuming. Polymerase chain reaction analysis is more convenient, but a potentially significant false-negative rate exists in the analysis of some antigen receptor genes as a result of using consensus primers and the process of somatic hypermutation. Chromosomal translocations, which result in oncogene activation, occur in many types of B- and T-cell lymphomas, and their detection is helpful in classification as well as in establishing a diagnosis of malignancy. Gene rearrangements and chromosomal translocations also can be used to monitor minimal residual disease. Tumor suppressor genes, although their analysis is relatively less useful for diagnosis, are involved in both pathogenesis and tumor progression and will be more important diagnostically as this field continues to expand. Molecular genetic analysis has played a major role in improving our understanding of Hodgkin disease.

CONCLUSIONS

Molecular genetic tests are currently important ancillary tools for the diagnosis and classification of malignant lymphomas, and their role is likely to increase in the future.

Seasonal variations in the onset of childhood leukaemia and lymphoma

Infection has long been suspected as a possible factor in the aetiology of leukaemia and lymphoma. If seasonal variation in the onset of disease could be shown in any of the diagnostic subgroups of leukaemia or lymphoma, this would provide supportive evidence of an aetiology linked to exposure to infection. All cases in the Manchester Children's Tumour Registry (aged 0-14 years at diagnosis) with acute lymphoblastic leukaemia (ALL), acute non-lymphocytic leukaemia (ANLL), Hodgkin's disease (HD) or non-Hodgkin lymphoma (NHL) between 1 January 1954 and 31 December 1996 were included in an analysis of seasonal variation in the month of first symptom and the month of diagnosis. Cases of common acute lymphoblastic leukaemia (c-ALL) diagnosed from 1979 onwards were also analysed separately. The groups considered for analysis were: all cases of ALL (n = 1070), ALL diagnosed between 18 and 95 months of age (n = 730), ALL diagnosed over 95 months of age (n = 266), c-ALL (n = 309), ANLL (n = 244), all infant acute leukaemias (ALL and ANLL under 18 months; n = 107), HD (n = 166) and NHL (n = 189). Using the Edwards method, both c-ALL and HD demonstrated significant seasonal variation (P = 0.037 and 0.001 respectively) in date of first symptom, with peaks occurring in November and December respectively. Using this method, no indication of seasonal variation was found in the other diagnostic groups for date of first symptom or in any of the diagnostic groups for date of diagnosis. For comparison with a previous study, a further analysis based on date of diagnosis for all ALL cases, using summer-winter ratios, showed a significant summer excess. These results provide supportive evidence for an infectious aetiology for c-ALL and HD, and possibly for all ALL, which warrants further investigation.

T-cell-rich B-cell lymphoma and Epstein-Barr virus infection of the uterus in a postmenopausal patient with an intrauterine contraceptive device in place for over 20 years

Although secondary involvement of the female genital tract occurs in up to 40% of cases of disseminated lymphomas, lymphomas presenting with primary female genital tract symptomatology are very unusual. We report a case of T-cell-rich B-cell lymphoma (TCRBCL) arising in the uterine corpus of a 57-year-old female who carried an intrauterine contraceptive device (IUD) for over 20 years. Malignant lymphoid cells expressed the Epstein-Barr virus (EBV) late membrane protein (LMP), a feature described in TCRBCL but not previously reported in primary uterine lymphomas. To our knowledge, this is the first reported case of a TCRBCL of the uterus.

Detection of EBV RNA (EBER-1 and EBER-2) in malaria lymph nodes by in situ hybridization

Acute Plasmodium falciparum malaria in African children allows expansion of latent Epstein-Barr virus infection, leading to colonization of lymph nodes by virus-infected lymphoblasts in 60% of cases as demonstrated by in situ hybridization for the detection of EBER-1 and EBER-2 RNA. This probably arises against a background of malaria-induced immunosuppression to EBV and concurrent lymphoid activation. The relevance of the results to the pathogenesis of African endemic Burkitt's lymphoma is discussed.

Epstein-Barr virus-associated Hodgkin's disease in HTLV-I seropositive patients: a report of two cases

Diagnosis of Hodgkin's disease (HD) is quite difficult in the patient with seropositivity for human T cell lymphotropic virus I (HTLV-I). Herein, two cases of Epstein-Barr virus (EBV)-associated HD, which occurred in males with seropositivity for anti-HTLV-I, are reported. One patient is alive and was diagnosed as having interfollicular HD with CD20+CD15-CD30-CD3-CD4-CD8-CD45RO-Read-Sternberg (R-S) cells. Positivity for EBV-encoded RNA 1 (EBER-1) and latent membrane protein 1 (LMP-1) was shown on follicular germinal center cells and R-S cells. In that case, neither T cell receptor (TCR) beta chain rearrangement nor integration of the HTLV-I provirus was demonstrated in the lymph nodes, although atyical lymphocytes (2%) were found in the peripheral blood. The other case pursued an aggressive clinical course and the patient was diagnosed as having an adult T cell leukemia/lymphoma (ATLL) because of the presence of anti-HTLV-I antibody, lymph node swelling, and the appearance of flower-like cells in the peripheral blood. However, an autopsy revealed no obvious ATLL cell infiltration in any of the organs examined. Multiple granulomatous lesions were found in the bone marrow, liver, kidneys, spleen, and lymph nodes. Reassessment of lymph node lesions in biopsies and granulomatous lesions in autopsy samples demonstrated that both lesions contained CD15+CD30+CD3-CD4-CD8-CD20-CD45RO-EBER-1+L MP-1+R-S cells, and they were considered to be a composite lymphoma of HD and ATLL. These two cases therefore suggest that EBV-associated HD can develop in patients with seropositivity for HTLV-I.

An immunohistochemical analysis of Reed-Sternberg-like cells in posttransplantation lymphoproliferative disorders: the possible pathogenetic relationship to Reed-Sternberg cells in Hodgkin's disease and Reed-Sternberg-like cells in non-Hodgkin's lymphomas and reactive conditions

The aim of this study was to assess the incidence and immunophenotype of Reed-Sternberg-like (R-S-like) cells in the setting of posttransplantation lymphoproliferative disorders (PTLD). Twenty-eight formalin-fixed, paraffin-embedded cases (17 renal and 11 heart/heart-lung PTLDS) were analyzed for the presence of typical binucleate cells with inclusionlike nucleoli--the Reed-Sternberg phenotype. An immunohistochemical evaluation for the following markers was performed: CD3, CD20, CD79a, CD15, CD30, CD45, EBV-LMP-1, and vimentin. Monoclonality was assessed by staining for light chain restriction. Eleven cases contained R-S-like cells (9 renal and 2 heart/heart-lung PTLD). All 11 cases were positive for CD45 (LCA), EBV-LMP-1, and vimentin. Ten of 11 cases were CD20/CD79a positive, one case being of a null immunophenotype. Nine cases expressed CD30, whereas 0 of 11 were positive for CD15. In nine cases, expression of both kappa and lambda light chains was present; the remaining two cases failed to express either light chain. This study shows that the R-S-like cells encountered in PTLD have an activated B cell immunophenotype, are invariably EBV-LMP-1 positive, are often CD30 positive, and are CD15 negative. This latter immunophenotypic feature separates R-S-like cells from the R-S cells seen in Hodgkin's disease. The strong staining for EBV-LMP-1 in R-S-like cells also indicates a strong association between EBV-LMP and the R-S morphological phenotype in the context of PTLDs.

Mitotic activity and nuclear DNA damage of large cells in Hodgkin's disease: comparison with the expression of p53 and bcl-2 proteins and the presence of Epstein-Barr virus

The roles of the bcl-2 and p53 proteins in Hodgkin's disease (HD) are poorly understood. We therefore compared their detected presence in Hodgkin and Reed-Sternberg/large atypical (H-RS/LA) cells immunohistochemically with the percentages of these cells double-labeled for CD30 and DNA strand breaks (DNA fragmentation index, DFI); mitotic indices (MI); and the EBV infection status. We found a highly significant inverse correlation between the fractions per case of H-RS/LA cells expressing bcl-2/p53 proteins and the DFI of CD30+ elements. No marked effect of these two oncoproteins on MI was noticed, although these parameters and DFI of CD30+ cells were linearly related. EBV infection of H-RS/LA cells exerted only a limited effect on the parameters tested. The results of this study suggest that overexpressed bcl-2 and, to some extent, p53 proteins in H-RS/LA cells of HD primarily counteract deletion of these cells.

Expression of Epstein-Barr virus latent membrane protein 1 protects Jurkat T cells from apoptosis induced by serum deprivation

It has been generally accepted that inhibition of apoptosis is important in the development of malignancy. To determine whether Epstein-Barr virus (EBV) latent membrane protein 1 (LMP1), the virus-coded transforming oncogene product, has an anti-apoptotic function in non-B-cells, Jurkat T cells were transfected with the LMP1-expression vector pSV2gptMTLM consisting of the human metallothionein promoter and were selected for mycophonolic acid resistance. LMP1-expressing clones of Jurkat cells showed resistance to apoptosis induced by serum deprivation. In LMP1-expressing clones, although the levels of Bcl-2 and Bax were similar to those in the clones of vector transfectants or parental cells, c-Myc expression was significantly depressed. Down-regulation of c-Myc by LMP1 was confirmed by using LMP1-expressing clones treated with CdCl2. Addition of c-myc antisense oligonucleotides to Jurkat cells specifically inhibited apoptosis induced by serum deprivation at the concentrations which suppressed c-Myc expression. These results suggest that LMP1 expression and subsequent down-regulation of c-Myc protect Jurkat T cells from apoptosis induced by serum deprivation. The significance of the anti-apoptotic function of LMP1 in non-B, Jurkat T cells is discussed in relation to the pathogenesis of EBV malignancy.

Epstein Barr virus in Argentine pediatric Hodgkin's disease

Since Hodgkin's disease (HD) is an heterogeneous condition with diverse histological and epidemiological subgroups, it seemed worthwhile to investigate the Argentine pediatric pattern. Moreover, the presence of Epstein Barr virus (EBV) infection occurs at different ages depending on the development status of the country. Thus, it was interesting to assess the relation between EBV and HD in the Argentine pediatric population. The age distribution profile of our pediatric HD patients showed a peak in early childhood which declined towards adolescence, closely resembling EBV infection pattern. Male:female ratio of the studied population was 3.2:1 and the histological subtype distribution disclosed that mixed cellularity HD (MCHD) was the most common, an epidemiological profile shared with other developing countries. Fifty percent of assessed HD cases were associated with EBV, showing a significantly higher prevalence in the 3-6 years-old group, indicating a non-random distribution. EBV was also present in most of MCHD cases and in some nodular lymphocyte predominance HD (nLPHD) but entirely absent in nodular sclerosis HD (NSHD). Both EBV subtypes, namely EBV-1 and EBV-2, were detected in studied HD cases. EBV-HD association in the Argentine pediatric population reveals typical epidemiological features indicating EBV as the aetiologic agent or, alternatively as a cofactor in a considerable percentage of such HD cases.

bcl-2 protein is strongly expressed in post-transplant lymphoproliferative disorders

The aim of this study was to examine a series of Epstein-Barr virus (EBV)-driven post-transplant lymphoproliferative disorder (PTLDs), in order to ascertain the level of bcl-2 immunostaining; to explore the relationship between bcl-2 and p53 protein expression and to see if any correlation exists between bcl-2 and EBV-latent membrane protein 1 (LMP-1). Seventeen renal and 11 heart/heart-lung PTLD cases were stained with antibodies to EBV-LMP-1, bcl-2 and p53, using paraffin-embedded tissue. All cases of PTLD strong co-expressed bcl-2 and EBV-LMP. Positive staining was present in small lymphoid and larger immunoblastic cells. These two antibodies showed parallel staining intensity. p53 expression was noted in 13 of 17 renal PTLDs, but in ten of the positive cases only 5-10 per cent of cells were stained. Seven of the 11 heart/heart-lung cases showed 50-60 per cent of cells to be p53-positive; in the remaining for cases, 10-20 per cent of cells were positive. bcl-2 protein, as detected by immunohistochemistry, is markedly overexpressed in all case of PTLD. This study also demonstrates a strongly positive correlation between bcl-2 expression and EBV-LMP-1 detection in PTLD. An inverse pattern of p53 and bcl-2 immunoexpression is noted in PTLDs with "high grade' histology: these show marked expression of bcl-2, while p53 is downregulated. A Fisher's exact test yielded a P value of 0-12 when comparing p53-positive renal PTLDs with p53-positive heart/heart-lung PTLDs, indicating that any difference seen is not statistically significant. The postulated mechanism for the positive correlation between bcl-2 and EBV-LMP-1 is that EBV upregulates bcl-2, either directly or indirectly, thus promoting cell survival and ultimately successful viral replication.

Phenotypic modulation of Hodgkin and Reed-Sternberg cells by Epstein-Barr virus

Expression of the Epstein-Barr virus (EBV) gene product LMP1 is found in tumour cells in varying proportions of Hodgkin's disease (HD) cases. It is not clear which cellular genes are influenced by EBV in HD. A total of 387 HD cases were tested for differences among LMP1-positive and -negative cases with respect to age, sex, histotype and immunophenotypic parameters (CD2, CD3, CD4, CD15, CD19, CD20, CD21, CD22, CD23, CD25, CD30, CD43, CD45RA, CD45R0, CD70, HLA-DR, T-cell receptor beta-chain, and p53 expression). Comparison of patient age and sex as well as distribution of histotype and tumour cell immunophenotype with published data suggests that the cases in this study are representative of the spectrum of HD in developed countries. LMP1 expression was found in 131/387 HD cases (36.4 per cent) with non-homogeneous distribution among HD histotypes, the mixed cellularity type (HDmc) being most frequently EBV-associated (71/129 cases, 55 percent). No relationship was found to age and sex. Significant phenotypic differences were restricted to the HDmc histotype, where the tumour cells expressed the activation marker CD30 in a larger proportion, and CD20 in a smaller proportion, when harbouring EBV. These results suggest that EBV may influence the tumour cell phenotype in HD.

Neoplastic cells of Hodgkin's disease show differences in EBV expression between Kenya and Italy

The Epstein-Barr Virus (EBV) has been implicated in the pathogenesis of Hodgkin's disease (HD). However, the association of EBV with this disease varies greatly from series to series and from country to country. Epidemiological studies have shown differences in HD occurring in different parts of the world. In particular, it has been reported that HD in developing countries differs from HD in Western countries in terms of epidemiological, pathological and clinical characteristics. These discrepancies among populations suggest an interaction with environmental factors and a direct role of different etiological agents. At present, there are no data on the frequency of association of EBV with HD in equatorial Africa. In this study, a large series of HD cases have been collected at the University of Nairobi, Kenya, and at the Universities of Bologna and Siena, Italy. The cases have been reviewed and classified according to the REAL Classification and the presence of EBV has been assessed by in situ hybridization (ISH). A statistical difference in EBV expression was found between HD from Kenya and HD from Italy. EBV-positive neoplastic cells were detected in 92% of Kenyan cases, whereas only 48% of Italian cases showed EBER1/2 positivity in the neoplastic cells. Our results suggest that, in Kenya, EBV plays a more direct role in the pathogenesis of HD, as it does for endemic Burkitt lymphoma.

Morphologic differences between latent membrane protein-1 (LMP-1)-positive and negative tumour cells in Epstein-Barr virus (EBV)-related childhood Hodgkin's disease. A morphometric study

The values of five cellular morphometric parameters (longest and shortest cytoplasmic axis, cellular circumference, area and roundness coefficient) were compared between 20 Latent Membrane Protein 1 (LMP-1)-positive and an equal number of LMP-1-negative Reed-Sternberg and Hodgkin (HRS) cells for each of 13 cases of Hodgkin's disease (HD) occurring in children (aged 3-15 years); the presence of Epstein-Barr virus (EBV) encoded EBER mRNAs had previously been detected in all cases using RNA in situ hybridisation (RISH), while the presence of LMP-1 was immunohistochemically detected using the alkaline phosphatase-antialkaline phosphatase (APAAP) method. The longest and shortest axis, circumference and area were larger in LMP-1-positive than in LMP-1 negative HRS cells, while the roundness coefficient of LMP-positive HRS cells was smaller than that of LMP-1 negative cells. All differences were statistically highly significant when univariate (paired comparisons) t-test were used. Multivariate analysis (Hotelling's T2 test) showed all differences (except the roundness coefficient) to be significant both at the 5% and 1% level of significance. These results provide a numerical basis for the alteration brought by the expression of LMP-1 in the cellular skeleton of tumour (HRS) cells in EBV-related childhood HD cases.

The role of Epstein-Barr virus in Hodgkin's disease from different geographical areas

Recent studies have suggested that Epstein-Barr virus (EBV) may play a role in the aetiology of Hodgkin's disease. To determine the role of EBV in childhood Hodgkin's disease in different geographical areas, immunohistochemical staining and in situ hybridisation were used to analyse latent membrane protein 1 (LMP 1) and small nuclear non-transcribed RNAs (EBER-1) respectively. Testing for EBV within the Reed-Sternberg and Hodgkin's cells was carried out in childhood Hodgkin's disease from 10 different countries. The proportion of LMP 1 positive cases varied significantly, being 50% of cases from the United Kingdom (38/75), South Africa (9/18), Egypt (7/14), and Jordan (8/16), 60% from the United Arab Emirates (6/10), 70% from Australia (11/16), 81% from Costa Rica (34/42), 88% from Iran (7/8), 90% from Greece (20/22), and 100% of the 56 cases from Kenya. A sensitive polymerase chain reaction based EBV strain typing technique was established using archival tissues. EBV strain type 1 was shown to be predominant in childhood Hodgkin's disease from the United Kingdom, South Africa, Australia, and Greece. Type 2 was predominant in Egypt. EBV strain types 1 and 2 were both detected in some cases of childhood Hodgkin's disease in the United Kingdom, Costa Rica, and Kenya. The high incidence of EBV and the presence especially in developing countries of dual infection with both strain types 1 and 2 may reflect socioeconomic conditions leading to malnutrition induced immunological impairment. The possibility of HIV infection also needs to be explored.

Down-regulation of Epstein-Barr virus nuclear antigen 1 in Reed-Sternberg cells of Hodgkin's disease

AIMS

To demonstrate Epstein-Barr virus (EBV) encoded nuclear antigen 1 (EBNA-1) gene expression in EBV associated disorders using a new monoclonal antibody (1H4-1) on routinely processed tissues.

METHODS

The pressure cooker antigen retrieval method was used for the immunohistochemical demonstration of EBNA-1 gene expression in formalin fixed, EBV positive tissues from Hodgkin's disease, infectious mononucleosis, HIV associated non-Hodgkin's lymphomas, post-transplant lymphomas, and undifferentiated nasopharyngeal carcinoma (NPC). EBV encoded EBNA-2, latent membrane protein 1 (LMP-1) and BZLF-1 gene expression was also examined using commercially available monoclonal antibodies.

RESULTS

Of the 34 EBER in situ hybridisation positive cases of Hodgkin's disease examined, none expressed EBNA-1 in the Reed-Sternberg cells. These cells were nevertheless strongly LMP-1 positive in all cases. Strong EBNA-1 staining was seen in all cases of EBER positive HIV associated non-Hodgkin's lymphoma (five of five), nasopharyngeal carcinoma (five of five), infectious mononucleosis (three of three), and post-transplant lymphoma (one of one). These cases also expressed LMP-1, EBNA-2 and BZLF-1, but at differing levels.

CONCLUSION

The pressure cooker antigen retrieval procedure is a sensitive and reliable adjunct to immunohistochemistry, especially with antibodies which are otherwise ineffective on routinely processed tissues. The EBNA-1 gene is not expressed at detectable levels in the malignant cells of Hodgkin's disease, but is consistently expressed in other EBV associated disorders. This finding has important implications for the role of EBNA-1 in the biology of EBV.