Overexpression of p53 in Hodgkin's disease: lack of correlation with Epstein-Barr virus infection

Expression of bcl-2 and p53 proteins in nasopharyngeal carcinoma. Absence of correlation with the presence of EBV encoded EBER1-2 transcripts and latent membrane protein-1

Aims-To investigate the immunohistochemical expression of bcl-2 and p53 proteins in nasopharyngeal carcinomas in relation to the expression of the Epstein-Barr virus (EBV) encoded EBER messenger RNAs (mRNAs) and latent membrane protein-1 (LMP-1).Methods-Formalin fixed, paraffin wax embedded tissue from 44 nasopharyngeal carcinomas (NPCs) was stained by immunohistochemistry for p53, bcl-2 and LMP-1 proteins and by RNA in situ hybridisation for EBER mRNAs.Results-The tumours were divided histologically into 13 cases of keratinising squamous cell NPC (KNPC), 15 cases of non-keratinising squamous cell NPC (NKNPC) and 16 cases of undifferentiated NPC (UNPC). Bcl-2 expression was observed in five of 15 NKNPC cases and in six of 16 UNPC cases; p53 expression was observed in one of 13 KNPC, two of 15 NKNPC and four of 16 UNPC cases. EBER 1-2 transcripts were detected in five of 15 NKNPC and nine of 16 UNPC cases, while LMP-1 expression was observed in one of 16 UNPC cases. All 13 KNPCs were EBV and bcl-2 negative. No correlation was found between the presence of EBER 1-2 transcripts and the detection of bcl-2 or p53 proteins, or both, in NPC cells.Conclusions-The expression of bcl-2 and p53 proteins may be associated with the level of the tumour cell differentiation in NPC. In addition, in view of the important role of the bcl-2 protein in the inhibition of apoptosis, the expression of bcl-2 protein may contribute to tumour cell survival in a proportion of NPCs. Furthermore, in the light of previous findings that the p53 gene in most UNPCs is in the wild-type configuration, mechanisms other than mutation may be responsible for stabilisation of the p53 protein in UNPCs.

Association between Epstein-Barr virus and Hodgkin's lymphoma in Belgium: a pathological and virological study

The association between Epstein-Barr virus (EBV) and classical Hodgkin's lymphoma (cHL) varies according to the geographic location. In this work we sought to characterize EBV involvement in a series of 111 cHL cases diagnosed in Belgium. The overall prevalence of EBV infection detected by in situ hybridization in Reed-Sternberg cells was 33%. EBV positivity correlated with older age at diagnosis (>54 years; p = 0.01), mixed cellularity subtype (p = 0.000001), male gender (p = 0.004) and tended to be associated with higher clinical stage (III/IV; p = 0.02). The molecular features of the virus in EBV-positive cHL were studied by comparison with a series of reactive tonsils. A 30-bp deletion within the LMP-1 gene was in 15/28 (53.6%) EBV-positive cHL cases, and in 41.7% of reactive tonsil samples. This variant did not correlate with any clinical or pathological feature. The EBV strain was type A in all cHL and reactive samples.

Proliferating cell nuclear antigen (PCNA), p53 and MDM2 expression in Hodgkins disease

CONTEXT AND OBJECTIVE

Tumor cells in Hodgkins disease (HD) express cell proliferation markers that are evaluated according to the oncogenes involved or the expression of their proteins. Correlations between the protein expression grade and clinical data are now important for disease prognosis.

DESIGN AND SETTING

This was a retrospective analysis on proliferating cell nuclear antigen (PCNA), p53 and MDM2 (murine double minute-2) expression using immunohistochemistry, on formalin-fixed, paraffin-embedded tissues from diagnostic biopsies on 51 patients with HD. The study was conducted at the Division of Hematology and Transfusion Medicine, Hospital São Paulo, Universidade Federal de São Paulo.

METHODS

Antigen expression was evaluated as the proportions of positive Hodgkin and Reed-Sternberg (HRS) cells and reactive lymphocytes (L), which were compared using Spearman correlation coefficients. The Friedman test was used for comparisons between the markers. The Pearson test was used to investigate associations between marker expression and clinical and laboratory parameters, marrow involvement, complete remission (CR) and overall survival (OS) rates.

RESULTS

There was overexpression of antigen proteins in HRS, in relation to L (p < 0.001). In HRS, MDM2 was higher than p53 and PCNA (p < 0.003), while the latter two were equivalent. In L, p53 was lower than MDM2 and PCNA (p < 0.001), while the latter two were equivalent. There was no relationship between protein expression and clinical and laboratory variables or outcome.

CONCLUSIONS

PCNA, p53 and MDM2 are tumor markers for HD, but showed no clinical or prognostic significance in our analysis.

TP53 gene mutations in Hodgkin lymphoma are infrequent and not associated with absence of Epstein-Barr virus

Reed-Sternberg (RS) cells, the neoplastic cells of Hodgkin lymphoma (HL) have clonal immunoglobulin gene rearrangements. The presence of somatic mutations suggests a germinal center origin, whereas the presence of crippling mutations suggests rescue of RS precursors from apoptosis by a transforming event. Epstein-Barr virus (EBV), which can be detected in 30-50% of HL cases, probably plays a role in this transforming event. The frequent presence of p53 protein expression in RS cells also suggests a role of the TP53 gene in this escape from apoptosis. Although mutations of the TP53 gene occur infrequently in RS cells, it has been suggested that in EBV-negative cases this gene mutation may be fundamental for the inhibition of apoptosis. In this study, we tested the hypothesis that there is an inverse correlation between the presence of TP53 gene mutations and the presence of EBV. In 21 of 67 cases EBV encoded small RNA (EBER)1-2 mRNAs were detected. Immunostaining for p53 protein revealed positivity in all 67 cases with variable percentages of positive cells and staining intensity. Screening for mutations in exons 5, 6, 7 and 8 of the TP53 gene in single RS cells obtained by laser microdissection from 26 HL specimens and 4 HL-derived cell lines revealed mutations in 2 of 15 EBV-positive cases and in 1 of 11 EBV-negative cases. Our results confirm the presence of infrequent (11.5%) TP53 gene mutations in HL and suggest that mutations of the TP53 gene are not correlated to the absence of EBV.

Fas ligand expression in Hodgkin lymphoma

Because previous investigations suggested involvement of the Fas ligand (FasL) in the selection process in the follicular dendritic cell (FDC)-associated cell cluster of the germinal center, we investigated the expression of FasL in Hodgkin lymphoma (HL) on protein and RNA level, while considering the Epstein-Barr virus status of the Hodgkin and Reed-Sternberg (HRS) cells. Tumor tissue from 47 patients with classic HL (32 nodular sclerosis [NS], 11 mixed cellularity [MC], and 4 lymphocyte-rich [LR]) was analyzed by immunohistochemistry for FasL, Fas, CD21, and CD23 and by Western blotting for FasL. FasL mRNA was detected by an exon 4-specific oligonucleotide and Epstein-Barr virus infection by in situ hybridization for Epstein-Barr virus early RNAs (EBER). Western blotting showed soluble and membrane-bound forms of FasL. Immunohistochemistry showed FasL expression in virtually all HRS of 94% of NS cases and 82% of MC cases. FasL expression did not correlate with the Epstein-Barr virus status of the HRS. Low FasL protein expression was found in some HRS of LR cases. FasL mRNA was detected in 39% of NS, 46% of MC, and 33% of LR cases. Seventy percent to 90% of the HRS cells expressed Fas. CD21 immunohistochemistry showed disrupted FDC networks in the tumor tissue with reduced and virtually absent expression of CD23 and FasL. These observations suggest that FasL expression in HRS cells and the absence of FasL in the FDC cluster represent a disturbed microenvironment that may be involved in the pathogenesis of HL.

Mutations of the p53 gene in nasal NK/T-cell lymphoma

Mutations of the p53 tumor suppressor gene are reported in various kinds of malignancies including lymphomas. However, p53 gene mutations in nasal NK/T-cell lymphoma have not been reported because most parts of tumors are necrotic and a small amount of living tumor tissues is available for the molecular study. Expression and mutations of the p53 gene were examined in the paraffin-embedded specimens of the nasal lesions from 42 Chinese (Beijing and Chengdu) and Japanese (Okinawa and Osaka) patients with nasal NK/T-cell lymphoma by the immunohistochemistry and single strand conformation polymorphism (SSCP) analysis of polymerase chain reaction (PCR) amplified products followed by direct sequencing. Thirty single-nucleotide substitution mutations were observed in 20 of 42 cases (47.6%). Among the 30 mutations, 18 were missense (mainly G:C to A:T transitions), 9 were silent, and 1 was a nonsense mutation. The remaining 2 mutations involved intron 5 and exon 5 terminal points. Abnormal expression of the p53 protein was also observed in 19 of 42 (45.2%) cases. The incidence was significantly (4-fold) higher in the cases of Osaka than those in other areas, although the incidence of p53 mutations in the cases of Osaka was one-half to one-third of those in the other three areas. The results may suggest some racial, environmental, or lifestyle differences in the cause of nasal tumorigenesis.

Lymphomas in patients with connective tissue disease. Comparison of p53 protein expression and latent EBV infection in patients immunosuppressed and not immunosuppressed with methotrexate

Cell cycle dysregulation as measured by p53 protein expression and latent Epstein-Barr (EBV) infection are important in the pathogenesis of lymphoma, particularly in immunosuppressed patients. Although latent EBV commonly is detected in lymphomas arising in patients with connective tissue disease who are immunosuppressed with methotrexate, p53 protein expression has not been reported. We compared the immunohistologic expression of p53 protein and the incidence of latent EBV infection in lymphomas arising in patients with connective tissue disease treated and not treated with methotrexate. Increased p53 staining was detected in 10 of 11 lymphomas arising in patients after methotrexate therapy vs 5 of 11 in patients not treated with methotrexate. Latent EBV was detected in 7 of 13 lymphomas arising in patients after methotrexate therapy vs 2 of 11 in patients not treated with methotrexate. Concordant p53 expression and latent EBV were detected in 5 of 7 lymphomas arising after treatment with methotrexate, including 1 that regressed after methotrexate therapy was withdrawn. These findings suggest that cell cycle dysregulation and EBV-related transformation are important in the pathogenesis of lymphomas arising in patients with connective tissue disease who are immunosuppressed with methotrexate.

Viral genotypes and p53 expression in Epstein-Barr virus-associated primary malignant lymphomas of the intestines

A small number (4% to 6%) of primary malignant lymphomas arising in the intestines express the EBV genome. However, in these tumors, the viral genotype and the role of tumor suppressor gene p53 have not been investigated. We sought to determine what genotype of EBV is frequently involved and whether the expression of p53 is related to these tumors. We used EBER-1 in situ hybridization and polymerase chain reactions (PCRs) for EBNA-1, EBNA-2A, and EBNA-2B to detect latent infection with EBV and to determine the genotype, respectively. In addition, we performed p53 PCR-SSCP (exons 5 through 9) and immunohistochemical analysis for p53. We found that EBV type B was present in 4 of 6 cases (67%); the genotype of the remaining cases could not be determined. The p53 PCR-SSCP indicated normal migration patterns in all malignant lymphomas, despite the fact that the tumor cells were strongly immunostained for p53 protein in 5 of the 6 cases. Thus, our study demonstrates that EBV-associated non-Hodgkin's lymphomas of the intestines in Korea are strongly related to the type B EBV and not to mutations of p53 gene. We suggest that EBV-associated intestinal lymphomas may arise through an interaction between the latent proteins of EBV and the wild-type p53 protein.

Oncogene expression in tumour cells of pediatric Hodgkin's disease in Argentina--correlation with Epstein Barr virus presence

A new category of oncogenes regulating apoptosis, p53 and bcl-2, and the Epstein Barr virus (EBV) latent membrane protein-1 (LMP-1) have been related to Hodgkin's disease (HD) pathogenesis. We attempt to determine p53, mdm2, p21waf-1, bcl-2 and LMP-1 immunohistochemical expression in tissue sections from formalin-fixed, paraffin-embedded lymph node biopsies of pediatric HD. P53 was detected in the nucleus of Reed Sternberg cells and their variants (H-RS) in 68% of the HD cases. However, there was no statistically significant association with either clinical stages or with histological subtypes. P21waf-1, an indirect marker of p53 functional status, showed nuclear labelling of H-RS in all the studied cases. MDM2 co-expressed with p53 in 62% of the cases, suggesting that both proteins regulate one another, in HD by a self regulatory loop. Bcl-2 cytoplasmatic expression in H-RS was demonstrated in 65% of the cases. There was co-expression of bcl-2 and p53 in 51%, but it failed to correlate with a poor prognosis. LMP-1 labelling was shown in 51% of the cases, disclosing a statistically significant association with the under 6-year group (p = 0.005, Fisher's exact test). Since LMP-1 induces the expression of bcl-2 in vitro, the relation of both proteins was analysed and found to co-express in 15/37 cases, with a statistically significant association only in the under 6-year group (p = 0.001, Fisher's exact test). Abnormal accumulation of these oncoproteins in tumour cells could play a role in the pathogenesis of a subset of pediatric HD.

Immunohistochemical Detection of the Epstein-Barr Virus–Encoded Latent Membrane Protein 2A in Hodgkin's Disease and Infectious Mononucleosis

We describe two new monoclonal antibodies specific for the Epstein-Barr virus (EBV)-encoded latent membrane protein 2A (LMP2A) that are suitable for the immunohistochemical analysis of routinely processed paraffin sections. These antibodies were applied to the immunohistochemical detection of LMP2A in Hodgkin's disease (HD). LMP2A-specific membrane staining was seen in the Hodgkin and Reed-Sternberg (HRS) cells of 22 of 42 (52%) EBV-positive HD cases, but not in 39 EBV-negative HD cases. In lymphoid tissues from patients with acute infectious mononucleosis (IM), interfollicular immunoblasts were shown to express LMP2A. This is the first demonstration of LMP2A protein expression at the single-cell level in EBV-associated lymphoproliferations in vivo. The detection of LMP2A protein expression in HD and IM is of importance in view of the proposed role of this protein for maintaining latent EBV infection and its possible contribution for EBV-associated transformation. Because LMP2A provides target epitopes for EBV-specific cytotoxic T cells, the expression of this protein in HRS cells has implications for the immunotherapeutic approaches to the treatment of HD.

Immunohistochemical Detection of the Epstein-Barr Virus–Encoded Latent Membrane Protein 2A in Hodgkin's Disease and Infectious Mononucleosis

We describe two new monoclonal antibodies specific for the Epstein-Barr virus (EBV)-encoded latent membrane protein 2A (LMP2A) that are suitable for the immunohistochemical analysis of routinely processed paraffin sections. These antibodies were applied to the immunohistochemical detection of LMP2A in Hodgkin's disease (HD). LMP2A-specific membrane staining was seen in the Hodgkin and Reed-Sternberg (HRS) cells of 22 of 42 (52%) EBV-positive HD cases, but not in 39 EBV-negative HD cases. In lymphoid tissues from patients with acute infectious mononucleosis (IM), interfollicular immunoblasts were shown to express LMP2A. This is the first demonstration of LMP2A protein expression at the single-cell level in EBV-associated lymphoproliferations in vivo. The detection of LMP2A protein expression in HD and IM is of importance in view of the proposed role of this protein for maintaining latent EBV infection and its possible contribution for EBV-associated transformation. Because LMP2A provides target epitopes for EBV-specific cytotoxic T cells, the expression of this protein in HRS cells has implications for the immunotherapeutic approaches to the treatment of HD.

A study of p53 protein, proliferating cell nuclear antigen, and p21 in Hodgkin's disease at presentation and relapse

About one fourth of patients with Hodgkin's disease relapse after therapy. The mechanisms that lead to resistance to treatment in these patients are poorly understood. The authors describe the differential protein expression of p53, proliferating cell nuclear antigen (PCNA), and p21 at initial presentation and relapse, and discuss their role in disease progression and resistance to therapy. Thirty-four patients with Hodgkin's disease who had relapsed after standard chemotherapy and radiotherapy regimens were assessed for the expression of p53 protein, PCNA, and p21 protein (waf/cip 1). In 14 of these cases, sequential biopsies performed both at presentation and at relapse were available for the study. Seventy-five percent of the cases were positive for the p53 protein. Tumors at relapse had higher p53 and PCNA scores than those at initial presentation. In the paired samples, a significant increase was noted in the number of p53 and PCNA-positive cells and in the intensity of staining with p53 antibody. Six of seven paired samples tested for p21 showed an increased p21 expression at relapse. These results suggest that, at relapse, Reed-Sternberg (RS) cells and their variants positive for p53, PCNA, and p21 are increased in number and individually have an increased expression of p53, PCNA, and p21 proteins. These findings suggest that therapy failure and relapse may, at least in part, be associated with altered p53, p21, and PCNA pathways. HUM PATHOL 28:549-555. This work was carried out during an exchange fellowship program at the National Cancer Institute, Bethesda. There are no restrictions on its use

MDM2 and p21WAF1/CIP1, wild-type p53-induced proteins, are regularly expressed by Sternberg-Reed cells in Hodgkin's disease

Mutations in the p53 tumour suppressor gene are the most common genetic alteration found in human cancers. Most of them are accompanied by stabilization of the protein, which renders it detectable through immunohistochemical techniques. Although p53 expression is a very common finding in Hodgkin's disease (HD), the status of the p53 gene is scarcely known, due to the difficulty in sequencing this gene in a lesion in which tumour cells are thought to constitute a very minor subpopulation, diluted in a background of supposedly benign cells. The pattern of expression of two downstream p53 proteins (MDM2 and p21 WAF1/CIP1, was studied as an indirect way of assessing p53 gene status. MDM2 is a wild-p53 inducible protein which may form a complex with p53, abrogating its function, as has been found in human sarcomas and other malignancies. p21WAF1/CIP1 is another protein inducible by wild-type p53, involved in inhibiting cell-cycle progression, through binding to cyclin/cyclin-dependent-kinase complexes. MDM2 and p21WAF1/CIP1 immunostaining was detected in all the cases analysed, independently of histological type, and were mainly present in Sternberg-Reed and Hodgkin (H & SR) cells. These immunohistochemical results were confirmed by Western blotting. To study the cause of MDM2 protein accumulation, MDM2 mRNA expression was also investigated by reverse transcription polymerase chain reaction (RT-PCR). The results show the presence of MDM2 transcripts in all cases of HD, albeit at lower levels than those found in reactive lymphoid tissue. These results seem to support the hypothesis that p53 is transcriptionally active in at least some of the H & SR cells in HD, and is able to induce MDM2 and p21WAF1/CIP1 protein expression.

Pathophysiology of Hodgkin's disease: functional and molecular aspects

Hodgkin's disease (HD) is characterized by the presence of the typical, clonal malignant Hodgkin and Reed-Sternberg (H-RS) cells in a hyperplastic background of normal reactive lymphocytes, plasma cells, histiocytes, neutrophils, eosinophils and stromal cells. The neoplastic nature of HD is based on aggressive clinical progression, presence of the proliferating and atypical H-RS cells, aneuploidy and cellular clonality. Immunophenotypical studies have demonstrated frequent expression of lymphoid "activation markers' including CD15, CD25, CD30, CD40, CD54, CD70, CD71, CD80, CD86 and MHC class II and less frequent expression of T- or B-cell-associated antigens by the neoplastic H-RS cells. The clonality of H-RS cells is demonstrated by clonal EBV integration, clonal cytogenetic abnormalities including p53 mutations and clonal immunoglobulin rearrangements in some HD cases. There is involvement of diverse molecules with oncogenic potential, including presence of viruses (Epstein-Barr virus and human herpes virus-6) and/or oncogenes/tumour suppressor genes (bcl-2/bcl-x, p53/MDM-2, c-myc, c-fms, N-ras, lck). The histopathological presentation and characteristic clinical features of HD correlate with an unbalanced production of multiple cytokines and define HD as a tumour of cytokine-producing cells. The proportion of malignant H-RS cells to reactive cellular components and fibrosis is dependent on the production of particular cytokines and allows subtyping of HD cases. The combined use of immunohistochemical, biochemical and molecular techniques has thus allowed recognition that HD represents more than one clinico-pathological entity with different types of H-RS cells. The defined mechanism for the biological nature, origin and oncogenesis of H-RS cells remains not fully understood, but is susceptible to further analysis using modern technology.

The epidemiology of Hodgkin's disease

Much of the epidemiological heterogeneity of HD incidence reflects the behaviour of the NS subtype, at least in the USA. Incidence variation across races (except Asians) and time periods is most marked in this subtype. In young adults with HD, there is compelling evidence for social class modification of risk consistent with an infectious aetiology; limited data suggest that this effect occurs within the NS subtype, but considerable evidence indicates that it does not primarily involve EBV infection. Findings from familial aggregation studies and HLA associations point to inherited susceptibility to this subtype. Despite little sex difference for NS in young adulthood in the latest incidence data, parity nevertheless appears to be protective against this subtype for women. Therefore, the greater increase for females than males in the incidence of young-adult NS in recent years may reflect the impact of population trends towards later childbearing and lower parity. This change, as well as the concomitant smaller family sizes and growing affluence, could explain part of the burgeoning incidence of NS in young adults in the USA. These observations suggest that NS in young adults constitutes a separate disease, probably of infectious origin. The incongruous occurrence of this subtype in older adults, and the presence of EBV in some NS cases, could reflect heterogeneity within NS, for example, representing features of the cellular phase of NS (Cozen et al, 1992; Medeiros and Greiner, 1995). For the non-NS subtypes, many of the factors that predict risk of NS may also be relevant. Patterns of social class determinants in children and older adults, the age groups at risk for MC, support involvement of an infectious precursor given intense exposure, and EBV is a likely candidate, based on its high prevalence in these groups. However, little aetiological research has been directed explicitly at the non-NS subtypes. Considerable effort has gone into exploring an infectious aetiology of HD. Recently, this line of investigation has moved beyond social class determinants to molecular epidemiological studies of EBV and, to a lesser degree, other potentially involved viruses. The roles of genetic susceptibility and sex hormones also represent promising areas for exploration, particularly in their possible interaction with infectious agents and other environmental factors. Ultimately, clearer epidemiological understanding of HD will be aided by more precise classification of this disease at the molecular level.

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.

The association of the Epstein-Barr virus with malignant lymphoma

The Epstein-Barr virus, a human herpesvirus, has been found in the neoplastic cells of numerous lymphoid malignancies, including Burkitt's lymphoma, immunodeficiency-associated lymphoproliferative disorders, nasal T/NK lymphoma, and Hodgkin's disease. The available data suggest that Epstein-Barr virus contributes to the pathogenesis of many of these neoplasms but is not directly linked to the etiology of any of these lymphomas.

Epidemiology of EBV and Hodgkin's lymphoma

The incidence of Hodgkin's disease shows marked heterogeneity with respect to age, gender, race, geographical locale, social class and histological subtype. The Epstein-Barr virus (EBV) is associated with a proportion of cases, approximately 40% in developed countries, and there is a body of evidence which suggests that mixed cellularity Hodgkin's disease is more likely to be EBV-associated than nodular sclerosis Hodgkin's disease. This study investigates the relationship between EBV and both age and histological subtype. We confirm the above subtype distribution and that childhood and older adult cases are more likely to be EBV-associated than young adult cases. Young adult nodular sclerosis cases are rarely EBV-associated providing further evidence that this is a separate disease entity. The results of this study support the multiple aetiology hypothesis which suggests that Hodgkin's disease in different age groups has different aetiologies. The epidemiology of Hodgkin's disease and studies investigating the distribution of EBV-associated cases are reviewed.

Non-Hodgkin's lymphoma, coeliac disease, and Epstein-Barr virus: a study of 13 cases of enteropathy-associated T- and B-cell lymphoma

A group of 166 patients with coeliac disease was followed for a period of up to 25 years. During this time, 17 patients developed intestinal tumours that were diagnosed as lymphoma, of which 15 cases were available for review. Eleven of the lymphomas were of T-cell type (enteropathy-associated T-cell lymphoma, EATL) and two were of B-cell type. Two cases were reclassified as undifferentiated carcinoma. The interval between the diagnosis of enteropathy and the onset of lymphoma varied from less than 2 months in four patients to more than 5 years in seven. Seven of the T-cell and both B-cell lymphomas were investigated for the presence of Epstein-Barr virus (EBV) by in situ hybridization (ISH) using probes against Epstein-Barr virus-encoded RNAs (EBERs) and by immunohistochemistry with EBV-specific monoclonal antibodies. All EATL cases were negative, suggesting that EBV is not an important factor in these cases. In one of the B-cell cases, EBV was detectable by ISH and immunohistochemistry in most tumour cells in the mesenteric lymph nodes, but not in any of the tumour cells in the primary ileal tumour, indicating that in this case EBV infection was a late event in the neoplastic process. These results show that lymphoma may develop any time after the onset of coeliac disease and that in our cases of EATL, EBV was not an important factor. In some cases of EBV-related neoplasia, virus infection may be a late event.

p53 mutation and expression in lymphoma

Mutation and abnormal expression of p53 was studied in 38 lymphomas [five Hodgkin's disease and 33 non-Hodgkin's lymphoma (NHL)]. CM1 polyclonal antibody was used to detect overexpression of p53. Three missense mutations were characterised in three cases of NHL after screening exons 5-8 of p53 of all the tumours with single-strand conformation polymorphism (SSCP) analysis. Only two out of three tumours with a missense mutation showed abnormal expression of p53 as measured by CM1. Conversely, seven out of nine tumours with positive CM1 staining had no point mutation demonstrated. Overexpression of p53 in the cases of NHL occurred in three out of twenty four low-grade tumours and five out of nine high-grade tumours (Kiel classification). The results suggest that abnormalities of p53 are commoner in high-grade than low-grade NHL, and that positive immunocytochemistry cannot be used to determine which tumours have mutations of p53.

Detection of Epstein-Barr virus in Hodgkin's disease occurring in an Oriental population

Like Burkitt's lymphoma, the strength of association of Epstein-Barr virus (EBV) with Hodgkin's disease occurring in different populations and clinical settings is highly variable, being 30% to 50% in Western countries, nearly 100% in Third World countries like Peru and Honduras, and nearly 100% in patients seropositive for human immunodeficiency virus. Data on the Oriental populations are very limited. Therefore, the current study was performed on the Chinese population of Hong Kong, where the incidence of Hodgkin's disease is low and EBV seroconversion occurs early in life. Twenty-three consecutive samples of Hodgkin's disease collected from 18 male and five female patients over a 12-year period were studied. The first age peak occurred in the second decade of life, and the second peak in the seventh decade. Using the sensitive and specific EBV-encoded RNAs (EBERs) in situ localization technique, positive labeling of the Reed-Sternberg cells and their variants was detected in five of five samples (100%) of mixed cellularity, nine of 16 samples (56%) of nodular sclerosing, one of one sample (100%) of lymphocyte depleted, and none of one sample (0%) of nodular lymphocyte predominant Hodgkin's disease. Further analysis of the data by age group yielded the following results: four of five (80%) for age younger than 15 years, three of nine (33%) for age 15 to 49, and eight of nine (89%) for age 50 or higher, confirming the reported strong association of EBV with Hodgkin's disease at the extremes of life. The overall positivity rate was 65%, which was intermediate between that reported in the Western populations and that in the Third World countries. These findings can be explained by the epidemiological pattern of Hodgkin's disease in Hong Kong, in which the first age peak is left-shifted to a younger age compared with that of Western populations (but not as early as that observed in Third World countries), moving the peak toward an age bracket in which Hodgkin's disease shows stronger association with EBV.

Biopathologic features of Hodgkin's disease

The neoplastic nature of Hodgkin's disease (HD) is suggested by several lines of evidence, including aggressive clinical course, presence of proliferating atypical cells morphologically recognized as Hodgkin's and Reed-Sternberg cells (H-RS), aneuploidy, and, in the minority of cases, clonality. Nevertheless, the etiopathogenesis of HD still remains elusive, and probably diverse. This uncertainty is partly due to the peculiar histology of HD lesions, characterised by the paucity of the putative neoplastic cell component, i.e. H-RS cells, admixed to a variety of reactive cells which prevent an exhaustive investigation at molecular level. Nevertheless, the possible involvement of different molecules with oncogenic potential has been recently suggested on the basis of immunohistological and molecular biology studies. These include oncogenes such as bcl-2 and MDM2 and anti-oncogenes such as p53. In addition, a large amount of data has accumulated on the possible role of EBV infection in HD. The colonization of lymphoid tissues by immortalized H-RS cells can account for the derangement of cytokine networks leading to microenvironmental and systemic abnormalities. In addition, a variety of soluble receptors (sIL-2R, sCD30, sTNF-R), and adhesion molecules (sICAM-1) are abnormally produced at sites of disease involvement. Some of these molecules still retain the ability to bind their ligands and can potentially contribute to the derangement of immune mechanisms observed in HD. Many of these soluble molecules can also be found in the patient's sera providing new potential prognostic and follow-up parameters in HD patients. The comparative analysis of the same molecules within the tissue, using immunohistochemistry, and in the blood, using immunochemical assays, appears as a promising informative approach.

PCR-mismatch analysis of p53 gene mutation in Hodgkin's disease

Expression of the p53 protein can be detected by immunohistochemistry in Reed-Sternberg (RS) cells, the presumed neoplastic component of Hodgkin's disease (HD) lesions. At present, there is no clear molecular evidence that p53 positive immunostaining in HD correlates with the presence of mutations or other structural alterations of the p53 gene. To address this question, 49 cases of HD have been investigated for p53 expression by immunohistochemistry, using the DO1 monoclonal antibody on paraffin sections. Thirty-seven out of 49 cases (75 per cent) exhibited positive immunostaining restricted to RS cells and variants. Among these 37 positive cases, ten cases were selected on the basis of a rich content of RS cells showing virtually 100 per cent DO1 positivity. A PCR-mismatch strategy was chosen for the detection of p53 mutations. The threshold level of sensitivity was assessed on positive cell-line controls. A proportion of 10-15 per cent p53 mutated cells mixed in a normal population could be identified. Total genomic DNA was extracted from the ten selected HD cases and PCR amplification of exons 5-8 of the p53 gene was performed. Heteroduplex mismatch analysis revealed no structural alterations of the p53 gene in any case. In view of these findings, it appears unlikely that the sensitivity of the method by itself can fully explain the negative results, although this possibility cannot be completely ruled out. Thus, it is conceivable that p53 positive immunostaining in HD may not necessarily imply genomic alterations in the classic 'hot spot' regions and may be related to another mechanism of p53 protein stabilization.

Intravascular lymphomatosis of the CNS: clinicopathologic study and search for expression of oncoproteins and Epstein-Barr virus

Five cases of intravascular lymphomatosis (IVL) are reported. Diffuse or focal cerebral signs suggestive of vascular disease occurred in four cases, but case 5 presented with symptoms similar to Creutzfeld-Jakob disease. Clinical course ranged from two to eight months and diagnosis was made in all cases by autopsy. Neoplastic lymphoid cells mainly lodged in lumina of small vessels in many organs, but infarction was confined to the CNS. Some extravascular tumor cells were regularly seen. All cases corresponded to high-grade Non-Hodgkin lymphomas of B-cell type and displayed high proliferation indices. Different from findings in primary cerebral and nodal lymphomas, neither p53 nor bcl-2 oncoproteins were detectable. Absence of EBV genome and EBV latent membrane protein from IVL was demonstrated for the first time.

Expression of the p53 gene in Hodgkin's disease: dissociation between immunohistochemistry and clinicopathological data

Expression of the p53 protein has been detected recently by immunohistochemistry in Hodgkin's disease (HD), but the relationship between p53 expression and the prognosis and clinicopathological heterogeneity of HD is still unclear. To address these questions we investigated 49 cases of HD for p53 expression by immunohistochemistry using the DO1 monoclonal antibody (MAb) on paraffin sections. Thirty-five cases were simultaneously tested with the 1801 MAb on frozen sections. Thirty-seven of 49 cases (75%) were DO1 positive while 14 of 35 (40%) were PAb 1801 positive. Both MAbs gave a nuclear staining restricted to Reed Sternberg cells (RSCs) and variants and distributed among the three HD subtypes analyzed (ie, nodular lymphocyte predominant, nodular sclerosing, and mixed cellularity). The percentage of positive neoplastic cells in each case was heterogeneous, ranging from almost 100% to less than 5%. In 39 patients for whom clinical data were available statistical analysis did not show any significant correlation between p53-positive immunostaining and clinical staging, B symptoms, probability of relapse, or disease-free survival. We conclude that p53 expression is a common event in HD regardless of histological subtyping, but does not bear any pejorative significance.

P53 overexpression and Epstein-Barr virus infection in undifferentiated and squamous cell nasopharyngeal carcinomas

We have analysed 22 nasopharyngeal carcinomas (NPCs) for expression of the small nuclear Epstein-Barr virus (EBV)-encoded RNAs (EBERs) and for immunohistologically detectable overexpression of p53. In situ hybridization demonstrated expression of the EBERs in 13 undifferentiated NPCs while nine squamous cell NPCs were EBER-negative. These results therefore confirm our previous DNA-DNA in situ hybridization studies and demonstrate that in the nasopharynx EBV is exclusively associated with undifferentiated but not with squamous cell carcinomas. p53 overexpression was demonstrated by immunohistology in 5 of 9 squamous cell NPCs and in 9 of 13 undifferentiated NPCs. Thus, there appears to be no correlation of p53 overexpression with EBV infection. These results are unexpected in the light of previous studies demonstrating that the p53 gene in primary undifferentiated NPC is consistently in the wild-type configuration. By contrast, analyses of squamous cell carcinomas of the head and neck have demonstrated that p53 overexpression in these cases is the result of p53 gene mutation. Whilst more detailed genetic analysis is required, our results suggest that mechanisms other than mutation of the p53 gene may be responsible for the stabilization of the protein in cases of undifferentiated NPC. It is tempting to speculate that an EBV-encoded protein may be involved.