Epstein-Barr virus-specific cytotoxic T-cell recognition of transfectants expressing the virus-coded latent membrane protein LMP

Current State of Knowledge on Primary Sjögren's Syndrome, an Autoimmune Exocrinopathy

Primary Sjögren's syndrome (pSS) is a chronic systemic autoimmune rheumatic disease characterized by lymphoplasmacytic infiltration of the salivary and lacrimal glands, whereby sicca syndrome and/or systemic manifestations are the clinical hallmarks, associated with a particular autoantibody profile. pSS is the most frequent connective tissue disease after rheumatoid arthritis, affecting 0.3-3% of the population. Women are more prone to develop pSS than men, with a sex ratio of 9:1. Considered in the past as innocent collateral passive victims of autoimmunity, the epithelial cells of the salivary glands are now known to play an active role in the pathogenesis of the disease. The aetiology of the "autoimmune epithelitis" still remains unknown, but certainly involves genetic, environmental and hormonal factors. Later during the disease evolution, the subsequent chronic activation of B cells can lead to the development of systemic manifestations or non-Hodgkin's lymphoma. The aim of the present comprehensive review is to provide the current state of knowledge on pSS. The review addresses the clinical manifestations and complications of the disease, the diagnostic workup, the pathogenic mechanisms and the therapeutic approaches.

Expression of the vault RNA protects cells from undergoing apoptosis

Non-protein-coding RNAs are a functionally versatile class of transcripts exerting their biological roles on the RNA level. Recently, we demonstrated that the vault complex-associated RNAs (vtRNAs) are significantly upregulated in Epstein-Barr virus (EBV)-infected human B cells. Very little is known about the function(s) of the vtRNAs or the vault complex. Here, we individually express latent EBV-encoded proteins in B cells and identify the latent membrane protein 1 (LMP1) as trigger for vtRNA upregulation. Ectopic expression of vtRNA1-1, but not of the other vtRNA paralogues, results in an improved viral establishment and reduced apoptosis, a function located in the central domain of vtRNA1-1. Knockdown of the major vault protein has no effect on these phenotypes revealing that vtRNA1-1 and not the vault complex contributes to general cell death resistance. This study describes a NF-κB-mediated role of the non-coding vtRNA1-1 in inhibiting both the extrinsic and intrinsic apoptotic pathways.

Epstein-Barr virus latent genes

Latent Epstein–Barr virus (EBV) infection has a substantial role in causing many human disorders. The persistence of these viral genomes in all malignant cells, yet with the expression of limited latent genes, is consistent with the notion that EBV latent genes are important for malignant cell growth. While the EBV-encoded nuclear antigen-1 (EBNA-1) and latent membrane protein-2A (LMP-2A) are critical, the EBNA-leader proteins, EBNA-2, EBNA-3A, EBNA-3C and LMP-1, are individually essential for in vitro transformation of primary B cells to lymphoblastoid cell lines. EBV-encoded RNAs and EBNA-3Bs are dispensable. In this review, the roles of EBV latent genes are summarized.

HLA associations in classical Hodgkin lymphoma: EBV status matters

The pathogenesis of classical Hodgkin lymphoma (cHL) involves environmental and genetic factors. To explore the role of the human leukocyte antigen (HLA) genes, we performed a case-control genotyping study in 338 Dutch cHL patients using a PCR-based sequence-specific oligonucleotide probe (SSOP) hybridization approach. The allele frequencies were compared to HLA typings of more than 6,000 controls. The age of the cHL patients varied between 13 and 81 years with a median of 35 years. Nodular sclerosis subtype was the most common subtype (87%) and EBV was detected in 25% of the cHL patients. HLA-B5 was significantly increased and HLA-DR7 significantly decreased in the total cHL patient population as compared to controls. Two class II associations were observed to be specific for the EBV- cHL population with an increase of HLA-DR2 and HLA-DR5. Allele frequencies of HLA-A1, HLA-B37 and HLA-DR10 were significantly increased in the EBV+ cHL population; these alleles are in strong linkage disequilibrium and form a common haplotype in Caucasians. The allele frequency of HLA-A2 was significantly decreased in the EBV+ cHL population. Analysis of haplotypes with a frequency of >1% revealed a significant increase of HLA-A2-B7-DR2 in EBV- cHL as compared to controls. SSOP association analysis revealed significant differences between EBV+ and EBV- cHL patients for 19 probes that discriminate between HLA-A*01 and HLA-A*02. In conclusion, the HLA-A1 and HLA-A2 antigens and not specific single nucleotide variants shared by multiple alleles are responsible for the association with EBV+ cHL. Furthermore several new protective and predisposing HLA class I and II associations for the EBV+, the EBV- and the entire cHL population were identified.

Multiple HLA class I and II associations in classical Hodgkin lymphoma and EBV status defined subgroups

The pathogenesis of classical Hodgkin lymphoma (cHL) involves environmental and genetic factors. To explore the role of the human leukocyte antigen (HLA) genes, we performed a case-control genotyping study in 338 Dutch cHL patients and more than 5000 controls using a PCR-based sequence-specific oligonucleotide probe hybridization approach. HLA-A68 and HLA-DR11 (5) were significantly increased in the cHL patient population compared with the controls. Three class II associations were observed in the EBV(-) cHL population with an increase of HLA-DR15 (2) and a decrease of HLA-DR4 and HLA-DR7. Allele frequencies of HLA-A1, HLA-B37, and HLA-DR10 were significantly increased in the EBV(+) cHL population; these alleles are in strong linkage disequilibrium and form a common haplotype in whites. The allele frequency of HLA-A2 was significantly decreased in the EBV(+) cHL population. Sequence-specific oligonucleotide probe analysis revealed significant differences between EBV(+) and EBV(-) cHL patients for 19 probes that discriminate between HLA-A*01 and HLA-A*02. In conclusion, the HLA-A1 and HLA-A2 antigens and not specific single nucleotide variants shared by multiple alleles are responsible for the association with EBV(+) cHL. Furthermore, several new protective and predisposing HLA class I and II associations for the EBV(+), the EBV(-), and the entire cHL population were identified.

Antiviral agent cidofovir decreases Epstein-Barr virus (EBV) oncoproteins and enhances the radiosensitivity in EBV-related malignancies

The Epstein-Barr virus (EBV) is involved in the carcinogenesis of several human cancers such as nasopharyngeal carcinoma (NPC) and Burkitt lymphoma (BL). Given the consistent role of EBV in transformation and maintenance of malignant phenotype, antiviral strategies provide an attractive approach to target EBV-expressing cells. In that aim, we have tested the Cidofovir, which is an acyclic nucleoside phosphonate analog known to exert an antiproliferative activity in some human virus-related tumors. Here, we show that Cidofovir induces a downregulation of the EBV oncoprotein LMP1 associated with a decrease of the antiapoptotic Bcl-2 and an increase of the proapoptotic Bax protein in Raji (BL) and C15 (NPC) cells. Using BL cell line BL2 B95-8 (BL2 infected with the B95.8 strain of EBV), we addressed the relation between EBV genome expression and modulation of viral oncoproteins by Cidofovir and/or ionizing radiation (IR). Cidofovir was able to significantly reduce LMP1 and EBNA2 mRNA and protein expression. This effect was associated with inhibition of proliferation, stimulation of apoptosis, and decrease of Bcl-2 expression in BL2 B95.8 cells. In addition, Cidofovir enhanced the radiation-induced apoptosis and the radiosensitivity through the proteolytic cleavage of death effectors caspase-9 and -3, which was specifically induced by combined treatment in EBV-positive cells compared to their negative counterparts. Furthermore, the combined treatment in nude mice led to a complete tumor remission without increasing toxicity in two human EBV-related cancer xenografts (Raji and C15). These results provide the basis for a novel anticancer strategy to enhance the therapeutic ratio of IR in EBV-related cancers.

Presence of human beta- and gamma-herpes virus DNA in Hodgkin's disease

Herpes viruses have been implicated in the etiology of Hodgkin's disease (HD). We studied the prevalence of human cytomegalovirus (CMV), human herpes viruses type-6 (HHV-6), type-7 (HHV-7) and type 8 (HHV-8) DNA in up to 88 Hodgkin's disease biopsies in comparison to Epstein-Barr virus (EBV) DNA by polymerase chain reaction (PCR). Non-Hodgkin lymphomas (NHL) and reactive lesions served as controls. CMV and HHV-6 were found in 8/86 (9%) and 11/88 (13%) HD cases, respectively, by nested primer PCR. Except for three cases harbouring HHV-6 type-B, only HHV-6 type-A was detected in HD. HHV-7 was observed by nested PCR in 33/88 (38%) HD cases and was already detectable in 15/88 (17%) HD cases by a single-round PCR indicating elevated virus copy numbers. Seven of these cases showed co-infection with HHV-6, and 11 cases were found to contain EBV DNA. 7/8 CMV-positive HD cases also harboured EBV DNA. HHV-8 DNA was not detected by single round or nested PCR in any HD case investigated. Thus, CMV, HHV-6, and HHV-7 were present in small proportions of HD cases, with frequent co-infection of HHV-6 and HHV-7, and frequent association with EBV. In contrast to EBV, beta-herpes viruses are therefore unlikely to have a role in the aetiology of HD. Rather, the presence of these viruses seems to reflect impaired immunological surveillance.

Epstein-Barr virus expression in Hodgkin's disease in relation to patient characteristics, serum factors and blood lymphocyte function

Epstein-Barr virus (EBV) expression was investigated by immunohistochemistry (latent membrane protein 1 [LMP-1]) and in situ hybridization (EBV encoded RNA [EBER]) in biopsies from 95 patients with untreated Hodgkin's disease (HD). Tumour EBV status was related to EBV antibody titres, spontaneous and concanavalin A induced blood lymphocyte DNA synthesis, serum levels of soluble (s) CD4, sCD8, sCD25, sCD30, sCD54, beta2-microglobulin, thymidine-kinase, routine chemistry, patient characteristics, complete remission and survival. The median follow-up time was 145 months (range 60-257). Tumour EBV-positive (n = 30; 33%) and negative (n = 62; 67%) patients did not differ with regard to sex, age, stage, presence of bulky disease or B-symptoms, remission rate or survival. The proportion of EBV+ cases was significantly higher among patients with mixed cellularity histopathology (58%) as compared to the nodular sclerosis subtype (18%; P < 0.001). The total white blood cell (WBC) counts were significantly lower in EBV+ patients (P < 0.01), who also had significantly higher levels of sCD54 (P < 0.02) and a tendency towards lower levels of sCD30 (P = 0.056). Patients in the tumour EBV+ group had significantly higher IgG antibody titres to restricted early antigen (EA-R) (P < 0.02). Hence, clinical features and outcome were not related to tumour EBV status. However, HD patients with EBV+ tumours had elevated sCD54 levels, higher antibody titres to EA-R and decreased total WBC counts. A potential causal relationship between EBV tumour status and these findings needs to be further explored.

Interleukin-10 levels are often elevated in serum of adults with Hodgkin's disease and are associated with inferior failure-free survival

BACKGROUND

Interleukin-10 (IL-10) is a pleiotropic cytokine that protects B- or T-lymphocytes and hemopoietic progenitors from apoptosis induced by doxorubicin, glucocorticoids, or deprivation of growth factors. IL-10 is also immunosupressive, and tumor cells secreting IL-10 can grow in syngeneic or allogeneic hosts, and can inhibit the generation of tumor-specific cytotoxic T cells. Hodgkin-Reed-Sternberg cells are derived from follicular center B cells and they may be latently infected by EBV. When this occurs they often express IL-10. Based on these considerations we investigated the relationship between pretreatment serum IL-10 levels and failure-free survival (FFS) in Hodgkin's disease (HD).

PATIENTS AND METHODS

Untreated patients, older than 16 years, with biopsy-proven HD, were included if treated with ABVD or equivalent regimens, and if pretreatment serum was available. IL-10 levels were determined with a capture enzyme-linked immunoassay specific for cellular IL-10.

RESULTS

Among healthy adult volunteers serum IL-10 levels ranged from 4.8-9.8 pg/ml (mean 7.1, standard deviation 1.5 pg/ml). Therefore levels > or = 10 pg/ml were considered elevated. We identified 101 patients with available serum. Their median age was 32 years, and 60% had B-symptoms. Ann Arbor stage was I in 4, II in 21, III in 35, and IV in 41 patients. Histology was nodular sclerosis in 74, mixed cellularity in 12, lymphocyte predominance in six, lymphocyte depletion in one, and unclassified in eight patients. Pretreatment serum IL-10 levels were elevated in 51 patients, and were higher in those with serum albumin < 3.5 g/dl, B symptoms, serum beta 2-microglobulin > or = 2.5 mg/l, anemia, and AAS III or IV. After a median follow-up of 32 months for survivors, 20 patients have progressed, and the three-year FFS of those with high vs. normal serum IL-10 was 60% +/- 9 vs. 91 +/- 9% (50% vs. 50% of the population; P = 0.004 by log-rank). Among patients with Ann Arbor stage III or IV the three-year FFS for those with high vs. normal serum IL-10 (58 vs. 42% of the population) was 57 +/- 9% vs. 92 +/- 6% (P = 0.008 by log-rank). Multivariate analysis using Cox's proportional hazards model confirmed that IL-10 was an independent variable associated with inferior FFS in this population.

CONCLUSIONS

Elevation of serum IL-10 levels is frequent and is associated with inferior FFS in adults with ABVD-treated HD. This observation should be verified in other patient populations. In addition, the source and the role of IL-10 in the biology of HD should be further investigated.

Interleukin-10 expression and cytotoxic-T-cell response in Epstein-Barr-virus-associated nasopharyngeal carcinoma

Interleukin-10 (IL-10) is an inhibitory cytokine produced by various cell types. It exhibits strong sequence homology to BCRF-1 (viral IL-10, vIL-10), an open reading frame in the Epstein-Barr-virus (EBV) genome. Using in situ hybridization (ISH), polymerase chain reaction (PCR) and immunohistochemistry, we checked 41 cases of nasopharyngeal carcinoma (NPC), to study the presence of EBV in the tumor cells, as well as to clarify the relationship between IL-10 expression of the tumor cells and the response of cytotoxic T cells. IL-10 expression was studied by immunohistochemistry; as a result, 29 of 41 cases expressed EBER-1 RNA of EBV by ISH. In addition, 19 of the 29 with EBV and 9 of 12 without EBV cases expressed IL-10 in the tumor cells. The number of cytotoxic T cells increased in the tumor tissue, and the increase in the intratumoral stroma was stronger than in the remaining normal epithelia. The number of cytotoxic T cells also significantly increased in the cases with EBV. On the other hand, in the IL-10-positive series, the number of cytotoxic T cells decreased significantly more than in IL-10-negative series. In view of the established inhibitory effects of IL-10, expression of IL-10 may therefore be one of the mechanisms for NPC cells as well as EBV to counter local immune defense. However, we could not conclude whether or not IL-10 expression was directly induced by EBV.

Epstein-Barr virus in gastric carcinoma in Suzhou, China and Osaka, Japan: association with clinico-pathologic factors and HLA-subtype

Information on geographic differences of Epstein-Barr virus (EBV) positivity and association with HLA in gastric carcinoma are limited. Therefore, the association of gastric carcinoma with EBV was examined in 118 patients from Suzhou, China, where the incidence of nasopharyngeal carcinoma (NPC) is high, and in 216 patients from Osaka, Japan, where the incidence of NPC is low, NPC being one of the EBV-associated carcinomas. Expression of HLA-A2 was also examined in some of these cases. The EBV genome was evidenced by PCR and in the tumor cells by in situ hybridization in 7/90 and 9/151 of cases from Suzhou and Osaka, respectively. Immunohistochemistry revealed that cancer cells in all cases with EBV did not express latent membrane protein-I. Type A was found in all cases positive for EBV. Among several histologic and clinical factors, only age of patients showed a correlation with EBV positivity: patients over 60 showed a higher frequency than patients below 60 years of age (p < 0.05). Typing of the HLA-A locus was possible in 16 cases positive for the EBV genome: 3 of 4 cases from Suzhou and 4 of 7 from Osaka were positive for HLA-A2 products. Severe lymphoid cell infiltration was found in 2 of 7 cases and 1 of 4 cases with and without the HLA-A2 type, respectively. The reported frequency of EBV positivity in Chinese living in Taiwan and in Japanese living in Hawaii is higher than in Suzhou, China, and Osaka, Japan, respectively. Our findings suggest that EBV association with gastric carcinoma is influenced by environmental and cultural factors.

Epstein-Barr virus infection, Hodgkin's disease, non-Hodgkin's lymphoma, and reactive follicular hyperplasia in Japanese children: evaluation of paraffin-embedded specimens using polymerase chain reaction and immunohistochemistry

Epstein-Barr virus (EBV) infections are common in Japanese children, with infectious by EBV type 1. The relationships between EBV infection and lymphadenopathies in Hodgkin's disease (HD), non-Hodgkin's lymphomas (NHL), reactive follicular hyperplasia (RFH), and infectious mononucleosis (IM) in 37 Japanese children were evaluated. Formalin-fixed, paraffin-embedded lymph node specimens that were obtained at surgical resection or biopsy were evaluated for the presence of EBV DNA and the latent membrane protein-1 (LMP-1) using polymerase chain reaction (PCR) and immunohistochemical staining. The PCR detected EBV DNA in nine of 13 (69.2%) patients with RFH, including a case of IM, all three (100%) patients with HD, and one of 21 (4.8%) patients with NHL. All EBV-positive samples contained EBV type 1. Reed-Sternberg's cells in HD were immunohistochemically positive for LMP-1, whereas all cases of RFH and NHL were negative for LMP-1. Results suggest that EBV infection may be related to HD. Although no proof exists that EBV infection contributes to the transformation of cells, thus causing RFH or NHL, the present authors suggest that the EBV-positive cases in Japanese children demonstrate a relationship between the clinical and histopathological features of the lymphadenopathy and EBV-type 1 infection.

Hodgkin disease occurring in a patient with extremely high serum antibody titers to Epstein-Barr virus--associated antigens without chronic illness

PURPOSE

We described for the first time a patient with long-lasting, extremely high serum antibody titer against Epstein-Barr virus (EBV) viral capsid antigen and early antigen without clinical symptoms suggestive of active EBV infection; the patient finally developed Hodgkin disease (HD) after 7 years of follow-up.

PATIENT AND METHODS

High serum EBV antibody titers were noted at 2 years of age. Immunological evaluation was performed at the age of 7 years. EBV-specific cytotoxic T-lymphocyte activity was normal. None of the other results showed any significant abnormalities except for the abnormal antibody titers against EBV-associated antigens.

RESULTS

The patient developed HD at the age of 9 years. In addition, EBV genomes were found in the nuclei of Hodgkin and Reed-Sternberg cells in the lymph node.

CONCLUSIONS

This case suggests that (a) a patient with extremely high serum antibody titers against EBV-associated antigens may develop HD after a prolonged period, even though no clinical symptom suggestive of active EBV infection is observed; (b) EBV may play an important role in the occurrence of HD.

Association of Epstein-Barr virus (EBV) with Sjögren's syndrome: differential EBV expression between epithelial cells and lymphocytes in salivary glands

The association of Epstein Barr virus (EBV) with Sjögren's syndrome (SS) is still in dispute. This study is aimed to investigate the existence of EBV genomes and their products in salivary glands of SS. Salivary gland samples were surgically obtained from Chinese patients. EBV DNA was detected in three of seven cases by dot blot hybridization and in four of seven cases by in situ hybridization. The EBV-encoded small RNA-1 (EBER1) was detected in two of seven cases by in situ hybridization. The immunohistochemical staining of EBV proteins showed that the EBV latent membrane protein-1 was detected in four of seven cases and that BZLF1, BALF2, and gp350/220 proteins associating with virus production were not expressed. In eight controls, no positive signal was observed by these methods. DNA in situ hybridization identified ERV on both epithelial cells and lymphocytes. On the other hand, EBER1-positive signals were exclusively localized on lymphocytes. These results indicate that two forms of EBV infection may exist in salivary glands of SS. One is EBER1-positive latency in lymphocytes, the other is EBER1-negative latency in epithelial cells. Frequent EBV detection in salivary glands of SS suggests that EBV plays a role in the genesis of SS.

Expression of latent membrane protein 1 in clinically isolated cases and animal models of AIDS-associated non-Hodgkin's lymphomas

Epstein-Barr virus (EBV)-encoded latent membrane protein 1 (LMP1) is known to be expressed in non-Hodgkin's lymphomas (NHL) occurring in immunocompromised hosts, playing crucial roles in lymphomagenesis. LMP1 expression at the microscopic level, however, was reported to be limited to some, not all, neoplastic cells in each specimen studied. In order to determine whether LMP1 expression of NHL really is limited to some cells, five clinically isolated acquired immunodeficiency syndrome (AIDS)-associated and six experimental NHL were studied immunohistochemically, immuno-electron microscopically and flow cytometrically. The experimental models were the lymphocytic tumors produced in severe combined immune deficiency (SCID) mice after engrafting EBV-infected B cells. Light microscopy revealed intense LMP1-immunostaining in less than 5% of neoplastic cells in the NHL, weak staining in less than 50% and apparently unstained cells in over 50%. Immuno-electron microscopy revealed that the intensely stained cells were those undergoing degeneration, whereas a proportion of the remainder demonstrated patchy reactions on their cell membranes. The weakly stained cells were found to correspond to cells with several patches on their cell membranes. Flow-cytometric analysis demonstrated that a large proportion of the neoplastic cells expressed LMP1 to some extent. Taken together, the results suggest that most of the neoplastic cells expressed LMP1 molecules at quantitatively different levels, some of which were below the level detectable by light microscopy. The intensely stained cells were shown to be those undergoing degeneration.

Contribution of class I HLA-A2 antigen in immune reactions

The involvement of the Class I HLA-A2 antigen is briefly reviewed in relation to allograft rejection, the feto-maternal relationship, viral cytotoxic reactions and tumor immunity. It is suggested that the HLA-A2 molecule may have, as compared to other HLA Class I alleles, a dominant role as a restricting element in cytotoxic T-cell recognition in the feto-maternal relationship to male fetuses, in specific viral infections and in tumors. As compared to other HLA Class I alleles, its reduced expression or loss in a variety of tumors suggests its possible important role in tumor immune surveillance. The disappearance of HLA-A2 from tumor cells may eventually contribute to the escape from T-cell recognition of malignant cells.

The antigen-presenting cell function of Reed-Sternberg cells

Reed-Sternberg cells, the neoplastic cells of Hodgkin's disease, express all membrane molecules required to function as antigen-presenting cells (APCs), such as major histocompatibility complex (MHC) class II antigens and the recently characterized B7 proteins, which are of critical importance for APC to adequately stimulate CD4+ T cells. As APC do, Reed-Sternberg cells also express the adhesion molecules ICAM-1 (CD54) and LFA-3 (CD58), via which T cells are able to adhere to the cell. MHC antigens, B7 proteins as well as the adhesion molecules are expressed by Reed-Sternberg cells in virtually all cases of Hodgkin's disease, irrespective of the subtype. In vitro studies have shown that Hodgkin's disease-derived cell lines are potent stimulators of mixed lymphocyte cultures and that the MHC antigens, B7 proteins and the adhesion molecules, expressed by Hodgkin's disease-derived cell lines, are essential for such a function. Taken together, these data strongly suggest that Reed-Sternberg cells function as APC in vivo, and that the APC function of the cell is a major common denominator of Hodgkin's disease. The APC function of Reed-Sternberg cells does not support the hypothesis that they derive from dendritic cells, since activated B and T cells may also exert an APC function. Analysis of the antigens that are potentially expressed by Reed-Sternberg cells may greatly advance our knowledge on the pathogenesis of Hodgkin's disease and may allow the development of immunotherapy as an alternative treatment method.

Malignant histiocytosis derived from a common histiocyte clone in a patient with chronic Epstein-Barr virus infection

Epstein-Barr virus (EBV) has a particular propensity for B lymphocytes, but in a few cases it seems to play a role in histiocytic disorders and EVB DNA has been identified in histiocytes. To determine what kind of cell proliferate clonally, we studied a patient with malignant histiocytosis that developed after chronic EBV infection. Polymerase chain reaction (PCR) for lymphocyte-defined membrane antigen (LYDMA) of EBV, a marker of monoclonality, double stainings of cell markers (B, T lymphocytes; histiocytes), and in situ hybridization for EBV were performed in tissues obtained in 1987 and 1990 before the appearance of malignant histiocytosis and in 1991 after the disease was diagnosed. PCR for LYDMA from multiple samples during the disease showed the same single band, indicating that chronic EBV infection and malignant histiocytosis were caused by the same single virion. We also found a single terminal repeat band of EBV which supports this finding. In the studies of double stainings, EBV was present in histiocytes of the non-neoplastic early stage, and in the neoplastic cells of malignant histiocytosis. The histiocyte, infected with EBV, clonally expanded to result in malignant histiocytosis.

Characterization of the Epstein-Barr virus Fp promoter

Expression of the Epstein-Barr virus nuclear antigen-1 (EBNA-1) protein is mediated by the virus Fp promoter in Burkitt lymphoma and nasopharyngeal carcinoma. This promoter is silent in latently infected B lymphoblastoid and most Burkitt lymphoma-derived cell lines in vitro, which utilize separate promoters approximately 50 kb upstream of Fp to express EBNA proteins. Fp-mediated activation of EBNA-1 expression is also activated upon induction of the virus replication cycle. We previously demonstrated that activation of Fp in Burkitt cells requires cis-regulatory elements downstream of the site of transcription initiation. We have now mapped two positive regulatory elements within the Fp promoter. One element contains two potential binding sites for the cellular transcription factor LBP-1 between +138 and +150. A second regulatory element was mapped between +177 and +192 and can be specifically bound in vitro by protein from nuclear extracts of Burkitt cells. Although this element overlaps two partial E2F binding sites and Fp reporter plasmids could be activated in trans by the adenovirus E1A protein in cotransfection experiments, mutational analysis and DNA binding studies suggest that these are unlikely to be functional E2F response elements within Fp. We also demonstrate that Fp-directed transcription initiates at multiple sites within both the genome and the Fp reporter plasmids. However, the principal site of transcription initiation within the genome is not utilized within reporter plasmids, in which the majority of transcripts initiate at multiple sites between +150 and +200. This finding suggests that additional elements may be necessary for Fp to function normally in these assays or that the context of Fp within the viral genome is critical to its regulation.

Epstein-Barr virus-associated non-Hodgkin's lymphoma in HIV-infected patients

Epstein-Barr virus (EBV) has been implicated in the pathogenesis of many lymphoproliferations arising in diverse settings, including HIV-infection. The precise roles of EBV may differ between these settings. For example, both the frequencies of EBV-association and the specific c-MYC translocations differ between sporadic and African Burkitt's lymphoma. Similarly, the frequencies of EBV-association in HIV-infected patients differs between anatomical sites, types of NHL, and geographic locations. HIV-related NHL have genetic alterations similar to NHL arising in the general population, and have less in common with the lymphoproliferations which arise in the setting of transplantation. However, the patterns of latent EBV transcription in systemic HIV-related NHL is unique among NHL, suggesting that EBV may contribute differently to their pathogenesis.

Epstein-Barr virus in the proliferative diseases of squamous epithelium in the oral cavity

The presence of Epstein-Barr virus was analyzed in 79 cases of oral epithelial proliferative diseases by polymerase chain reaction, in situ hybridization for Epstein-Barr virus-deoxyribonucleic acid and Epstein-Barr virus-encoded small messenger ribonucleic acid and immunohistochemistry for Epstein-Barr virus latent membrane protein. These lesions were histologically categorized as invasive squamous cell carcinoma (n = 36), carcinoma in situ (n = 10), verrucous carcinoma (n = 4), leukoplakia (n = 19), and papilloma (n = 10). Epstein-Barr virus genomes were detected in 19 squamous cell carcinoma (52.8%), four carcinoma in situ (40%), and one leukoplakia (5.3%); none of the verrucous carcinoma or papilloma cases were positive with polymerase chain reaction. By deoxyribonucleic acid in situ hybridization, positive signals were observed in the nuclei of cancer cells in 10 cases, in infiltrating lymphocytes in three, and both in one case. In patients with carcinoma in situ, only a single case was positive. In one case of leukoplakia positive signals were found in upper and middle layer squamous cells. The results by Epstein-Barr virus-encoded small messenger ribonucleic acid in situ hybridization revealed the same distribution as that by deoxyribonucleic acid in situ hybridization. Latent membrane protein was expressed only in the epithelial cells of leukoplakia but not in cases with squamous cell carcinoma and carcinoma in situ. These findings suggest that Epstein-Barr virus infection of oral squamous epithelium may be carcinogenic; alternatively, the virus may merely exist in epithelial cells of squamous cell carcinoma, carcinoma in situ, and leukoplakia as a passenger.

Heterogeneity of Epstein-Barr virus infection in angioimmunoblastic lymphadenopathy type T-cell lymphoma

To investigate the relationship of Epstein-Barr virus (EBV) and angioimmunoblastic lymphadenopathy with dysproteinemia, we performed DNA analysis using the polymerase chain reaction (PCR), Southern blot, in situ hybridization, and immunohistochemical analysis of lymph nodes in five patients who were followed up and biopsied more than once. In the course of the disease, nodal architecture diminished, cellular atypia worsened, and clear cells increased in number. In the DNA analysis of the receptor genes, the clonal population increased in number. EBV nucleic acid sequences were found by either PCR or in situ hybridization in all examined nodes. The number of EBV-positive cells varied widely among the cases and throughout the course of the disease in the same patients. The analysis of EBV terminal repeats or lymphocyte-determined membrane antigen genes showed polyclonal populations of EB-infected cells. EBV-positive cells possessed intermediate- to large-sized nuclei, and the cells with large nuclei, especially, expressed latent membrane protein of EBV. These large cells varied among the cases. Double-labelling immunohistochemistry/in situ hybridization studies demonstrated that most of the EBV-positive cells expressed B-cell antigen (CD20). The presence of EBV seems to be associated with the selective defects of the immune system, rather than with the direct pathogenesis of angioimmunoblastic lymphadenopathy.

EBV gene expression, EBNA antibody responses and EBV+ peripheral blood lymphocytes in post-transplant lymphoproliferative disease

Epstein-Barr virus (EBV) is associated with the development of several B cell malignancies including Burkitt's lymphoma (BL), post-transplant lymphoproliferative disease (PTLD), and AIDS-related lymphomas. The latter two diseases result from EBV-driven B cell proliferation in the absence of normal immunosurveillance and as such, represent a heterogenous family of lymphoproliferative disorders. This article reviews studies on EBV gene expression and antibody development in PTLD and introduces recent information on the levels of EBV+ peripheral blood lymphocytes to discuss possible mechanisms of pathogenesis under varying conditions of immunosuppression.

Absence of HLA class I expression by Reed-Sternberg cells

The reactive cell population in Hodgkin's disease consists of predominantly CD4+ helper T cells and lacks CD8+ cytotoxic T cells and natural killer cells. This lack of a CD8+ response is surprising in view of the expression of the latent Epstein-Barr viral protein LMP by Reed-Sternberg cells in many cases of Hodgkin's disease, Deficient HLA class I expression would be one possible mechanism to avoid a CD8+ cytotoxic immune response. To test this possibility we studied the expression of HLA class I and II determinants on Reed-Sternberg cells in tissue sections and cell suspensions of Hodgkin's disease. Frozen tissue sections of 40 cases and cytocentrifuge preparations from cell suspensions of 10 lymph nodes involved by Hodgkin's disease were studied with monoclonal antibodies reactive with HLA determinants. As a control frozen tissue sections of two cases of infectious mononucleosis were studied. Careful examination of the tissue sections and subsequently of cytospins of cell suspensions showed that the Reed-Sternberg cells frequently lacked HLA class I but showed strong staining for HLA class II. Absence of HLA class I expression on Reed-Sternberg cells and their variants provides an explanation for the lack of a CD8+ cytotoxic immune response against antigens expressed on Reed-Sternberg cells.

Engraftment of human non-Hodgkin lymphomas in mice with severe combined immunodeficiency

BACKGROUND

Malignant non-Hodgkin lymphoma (NHL) is one of the most difficult neoplasms to transplant into nude mice. Mice with severe combined immunodeficiency (SCID) accept various human cancers much more efficiently than do nude mice. The authors investigated whether SCID mice could be used as convenient hosts in which to grow human NHL in vivo.

METHODS

Fifty NHL specimens were engrafted into SCID mice. The original specimens and the tumors that developed in SCID mice were studied immunohistologically and by Southern blot analysis to clarify their clonal identity and to determine if they were Epstein-Barr virus (EBV)-transformed B cell proliferations.

RESULTS

SCID tumors developed from 23 of 50 NHL specimens. Ten tumors were identical immunophenotypically and, partly, genotypically to the original NHL, showing that the original NHL grew in the SCID mice. B-cell NHL rather than T-cell NHL and high-grade rather than low-grade malignancy groups were much more easily heterotransplanted. Most of the heterotransplanted NHL were maintained by successive transplantation. In two other SCID tumors, the original NHL clones and a newly developed B-cell clone coexisted. The remaining 11 SCID tumors were composed of newly developed clones. The latter 13 tumors were shown to be human cells of B-cell lineage bearing EBV latent proteins--latent membrane protein 1 and EB nuclear antigen 2--suggesting that they originated from EBV-infected B-cells that were present in the original tumor tissues.

CONCLUSION

SCID mice accept human NHL far more efficiently than do nude mice. However, frequent occurrence of spontaneous EBV-associated B-cell proliferation must be kept in mind.

Epstein-Barr virus-latent gene expression and tumor cell phenotype in acquired immunodeficiency syndrome-related non-Hodgkin's lymphoma. Correlation of lymphoma phenotype with three distinct patterns of viral latency

We investigated 49 acquired immunodeficiency syndrome-related lymphomas (ARLs) for Epstein-Barr virus (EBV) by Southern blotting and in situ hybridization and, in positive cases, used cryostat immunohistology to compare EBV-latent gene expression (EBV encoded small RNA-1 [EBER-1], EBV nuclear antigen-2 [EBNA-2], latent membrane protein-1 [LMP-1] and host cell immunophenotype (CD11a, CD18, CD54, CD58, CD21, CD23, CD30, CD39, CDw70, immunoglobulin) patterns with those reported in other EBV infections. EBV+ immunoblast-rich/large cell ARLs (n = 22) showed three patterns of latency: broad (EBER+EBNA-2+/LMP-1+; n = 9), reminiscent of a lymphoblastoid cell line phenotype; restricted (EBER+/EBNA-2-/LMP-1-; n = 6), similar to endemic Burkitt's lymphoma; and intermediate (EBER+/EBNA-2-/LMP-1+; n = 7), a pattern rarely described in vitro but seen in certain EBV-related malignancies. EBNA-2 expression was associated with extranodal lymphomas. EBV+ Burkitt-type ARLs (n = 11) usually showed the restricted latency pattern (n = 8), but some expressed the intermediate form (n = 3). Adhesion (CD54, CD58) and activation (CD30, CD39, CDw70) molecule expression varied with morphology (immunoblast-rich/large cell versus Burkitt-type), but was not independently correlated with EBV-positivity. CD30 and LMP-1 expression were associated. ARLs show heterogeneity regarding both the presence of EBV and latency pattern. Comparison of these phenotypically distinct lymphoma groups with known forms of EBV infection provides clues to their possible pathogenesis.

Expression of Epstein-Barr virus latent gene products and related cellular activation and adhesion molecules in Hodgkin's disease and non-Hodgkin's lymphomas arising in patients without overt pre-existing immunodeficiency

Epstein-Barr virus (EBV) recently has been associated with Hodgkin's disease (HD) and the EBV genome was found in CD30-positive Reed-Sternberg cells. Therefore, tissue sections from 25 cases of HD, 35 cases of CD30-positive non-Hodgkin's lymphoma (NHL) (seven CD30-positive anaplastic large cell lymphomas [ALCLs] and 28 CD30-positive non-ALCLs), and 12 cases of CD30-negative NHL that previously had been screened for the presence of EBV by polymerase chain reaction and DNA in situ hybridization were studied by immunohistochemistry for the expression of the latent EBV proteins, latent membrane protein (LMP), and Epstein-Barr nuclear antigen-2 (EBNA-2). We also analyzed the expression of the B-cell activation molecule CD23 and the adhesion molecules LFA-1/CD11a and ICAM-1/CD54 because the upregulation of these molecules by LMP and/or EBNA-2 in vitro has been related to the EBV-induced lymphocyte growth. Latent membrane protein expression was found in Reed-Sternberg cells in nine of 25 cases (36%) of HD and in large, occasionally Reed-Sternberg-like tumor cells in six of 47 cases (12%) of NHL; these six tumors were CD30-positive, histologically high-grade NHL (one CD30-positive ALCL and five CD30-positive non-ALCLs). All the LMP-positive cases were also polymerase chain reaction EBV positive while LMP expression was not found in polymerase chain reaction EBV-negative HD and NHL. No staining for EBNA-2 was detected in our series. In view of the transforming potential of the LMP, these findings suggest that EBV may be associated with the development of some cases of HD and CD30-positive NHL. These findings also suggest a correlation between the expression of LMP and the detection of CD30 in tumor cells of HD and NHL. In contrast, no correlation was found between the expression of LMP and the detection of CD23, LFA-1/CD11a, and ICAM-1/CD54 in tumor cells of HD and NHL.

Tumor viruses in CD30-positive anaplastic large cell lymphomas

CD30+ anaplastic large cell lymphoma (ALCL) represents a novel lymphoma entity at the borderline between Hodgkin's disease and non-Hodgkin's lymphomas. Phenotypic, genotypic, and karyotypic analyses have shown that ALCL are heterogeneous in cellular origin, and may be conceived as malignancies derived from activated, mainly T- or B-lymphoid cells, in some instances with an immature genotype. Epstein-Barr virus genomes and gene products, most notably the transformation-associated latent membrane protein (LMP), have been detected in a proportion of cases, and some cutaneous ALCL proved to harbor complete or incomplete HTLV-1 proviruses. These findings suggest that both EBV and HTLV-I, which are powerful inducers of CD30 expression in lymphoid cells in vitro, may contribute to the pathoetiology of ALCL.

Influence of Epstein-Barr virus encoded latent membrane protein 1 on the expression of CD23 antigen, ICAM-1 and LFA-3 in Hodgkin and Reed-Sternberg cells. A morphometric analysis

Epstein-Barr virus (EBV) latent membrane protein 1 (LMP 1) is expressed in Hodgkin and Reed-Sternberg (HRS) cells in about one half of Hodgkin's disease (HD) cases. In vitro, LMP 1 induces B-cell expression of CD23 antigen, ICAM-1 and LFA-3. To evaluate the influence of LMP 1 on the expression of these molecules in HRS cells in vivo, we performed a quantitative frozen section immunohistological study comparing the numerical density (cells per unit area) of HRS cells expressing the CD23 antigen, ICAM-1 and LFA-3 in 14 LMP 1-positive and 13 LMP 1-negative HD cases. CD23 antigen was demonstrated in HRS cells in five LMP 1-positive and three LMP 1-negative cases (not significant). The relative density of HRS cells tended to be lower in the LMP 1-positive than in the LMP 1-negative cases, but this did not reach significance (0.2 > 2p > 0.1). All recognizable HRS cells expressed ICAM-1 and LFA-3 irrespective of LMP 1 status. We conclude that expression of CD23 antigen and LMP 1 are not coordinated in HD. Although LMP 1 may have some influence on CD23 antigen expression, it is unlikely that the latter is of importance in the putative EBV induced growth transformation of HRS cells in vivo.

Allelic variations clustered in the antigen binding sites of HLA-Bw62 molecules

HLA-Bw62 is a serologically defined class I antigen specificity, but we show that it represents a family of five distinct alleles in this study. Five variants of HLA-Bw62 antigens were identified by isoelectric focusing, and sequencing studies revealed that these are a family of closely related alleles differing from one another by one to six amino acid substitutions at eight positions: 63 in the alpha 1 domain and 94, 95, 97, 99, 113, 152, and 156 in the alpha 2 domain. These substitutions are located in the two alpha-helices and two adjacent beta-strands, and the side chains of most amino acids face into the antigen binding groove. Functional assays using an in vitro generated Epstein-Barr virus (EBV)-specific Bw62-restricted cytotoxic T lymphocyte clone indicated that the minimal structural variations located in the antigen binding sites of the HLA-Bw62 variant molecules could affect the presentation of the nominal EBV antigen. This study revealed that the HLA-Bw62 antigen family consists of at least five closely related alleles, and further demonstrated that these alleles with minimal structural variations might play distinct functional roles in regard to antigen presentation.

Demonstration of a unique Epstein-Barr virus-positive cellular clone in metachronous multiple localizations of Hodgkin's disease

The recent detection of clonal episomes of Epstein-Barr virus (EBV) in a significant proportion of Hodgkin's disease (HD) cases has suggested a re-evaluation of the possible pathogenetic role of EBV in the development of the disease. Here we report that in two EBV-positive HD, arisen in human immunodeficiency virus-1-infected drug users, a unique episomal EBV genome was detected in multiple metachronous HD lesions of each patient. These findings demonstrated that the same EBV-positive cellular clone was present in multiple localizations of HD as well as in specimens taken at different times. Combined in situ hybridization and immunohistological analyses evidenced EBV genome and EBV-encoded latent membrane protein-1 on Reed-Sternberg cells. Therefore, the data strongly support the possibility of a causal role for EBV in the pathogenesis of HD.

Generation of cytotoxicity with various MHC class I restrictions against autologous LCL by stimulating the lymphocytes with autologous and/or allogeneic LCLs sharing HLA alleles with the responder

We exposed human blood lymphocytes to autologous and to allogeneic lymphoblastoid lines (LCLs), each alone or in combination, and analyzed the MHC Class I restriction pattern of the generated auto-LCL reactive cytotoxicity. In the cultures of two EBV-seropositive, HLA A11-positive individuals the majority of cytotoxic lymphocytes generated after repeated stimulation with autologous LCL were restricted by this molecule. One of the cultures was subjected to various stimulation strategies. A relatively low proportion of HLA A2- and HLA B7-restricted cytotoxic T cells could be detected in the autostimulated cultures. Such cells were enriched at the expense of A11-restricted ones by stimulating with allogeneic LCLs which lacked HLA A11 but expressed A2 or B7. Interestingly, stimulation of the lymphocytes with only allogeneic LCL also generated autoreactive CTLs. Thus, by including or using exclusively allogeneic LCL stimulators, the CTL fractions represented by few cells could be enriched.

Viral involvement in Hodgkin's disease

The etiology of Hodgkin's disease (HD) is unknown, but a growing body of evidence suggests that the Epstein-Barr virus (EBV) plays a role in a proportion of cases. Clonal EBV genomes have been detected in affected tissues, and EBV has been localized to Reed-Sternberg (RS) cells, the putative malignant cells in HD. EBV latent genes, including the EBER RNAs and the latent membrane protein, LMP-1, are expressed by RS cells. These data suggest that EBV is playing a role in the pathogenesis of HD; however, it is clearly not involved in all cases. Using in situ hybridization, we can detect EBV within the RS cells in approximately 40% of cases. Epidemiological data suggest that HD is a heterogeneous condition and the distribution of EBV-associated cases is not random. Studies from several groups indicate that mixed cellularity cases are more likely to be EBV-associated than nodular sclerosis cases. Our data further suggest that the majority of pediatric and older cases of HD are EBV-associated, whereas the RS cells in young adult cases only rarely harbor EBV. We therefore speculate that another virus is responsible for the young adult peak in incidence which is seen in developed countries.

Epstein-Barr virus infection and associated diseases in children. I. Pathogenesis, epidemiology and clinical aspects

Epstein-Barr virus (EBV), an ubiquitous human B lymphotropic virus, is the cause of infectious mononucleosis. Moreover, EBV infection can be followed by lymphoproliferative diseases in patients with inherited and acquired immunodeficiencies. Primary EBV infection may be a threat to all children after marrow or organ transplantation or those receiving chronic immunosuppressive treatment for various other reasons. The virus has been also implicated in the pathogenesis of different malignant tumours such as Burkitt lymphoma, nasopharyngeal carcinoma, Hodgkin disease and some T-cell lymphomas. This review focuses on various aspects of virus-host interactions, immune mechanisms of the host, and the still experimental therapeutic approaches in EBV-associated diseases.

Biology of Hodgkin's disease

The biology of Hodgkin's disease is one of the most intriguing subjects in lymphoma research. The presence of only a small proportion of neoplastic cells and a vast majority of reactive cells reflects the presence of complex interactions between these cell types. In this paper we discuss findings indicating that Reed-Sternberg cells may be virally transformed cells that have evaded a cytotoxic immune response and induce an ineffective delayed type hypersensitivity reaction.

Expression of the Epstein-Barr virus latent membrane protein (LMP) in insect cells and detection of antibodies in human sera against this protein

Recombinant baculoviruses containing the complete LMP and truncated LMP genes were generated and high levels of the LMP proteins were expressed in Spadoptera Frugiperda insect cells. A specific rabbit antiserum directed against the N-terminal part of LMP was obtained by immunizing the rabbits with Escherichia coli-expressed trpE-N-terminal part of LMP fusion protein. A total of 127 human sera were studied for their immune response to the recombinant full-length LMP. In immunofluorescence analysis, all sera tested showed no detectable reaction with the recombinant full-length LMP. In immunoprecipitation-immunoblotting analysis, however, sera from patients with nasopharyngeal carcinoma (5/22), patients with Hodgkin's disease (16/27), patients with other diseases exhibiting high EA-IgG titers (3/52), and VCA-IgG-positive healthy individuals (2/26) were shown to contain antibodies against this recombinant LMP. The expressed LMP proteins provided a sufficient and economic source of the proteins for further serological and biological studies.

Expression of the Epstein-Barr virus (EBV)-encoded membrane protein LMP1 impairs the in vitro growth, clonability and tumorigenicity of an EBV-negative Burkitt lymphoma line

In a previous study on several independently established Epstein-Barr virus (EBV)-converted sublines of the EBV-negative Burkitt lymphoma (BL) line BL41, we found that expression of the virally encoded membrane protein LMP1 was accompanied by reduced agarose clonability and tumorigenicity. In order to investigate whether LMP1 can induce these phenotypic changes by itself, we have now studied the growth in suspension culture, the clonability in agarose and the tumorigenicity in immunosuppressed and SCID mice of 4 LMP1-transfected sublines of BL41 that carry the gene under the control of the ZnSO4-inducible metallothionein promoter. Expression of LMP1 at levels comparable to those detected in EBV-transformed lymphoblastoid cell lines (LCL) correlated with impairment of growth in suspension and reduction of clonability and tumorigenicity. Only minor changes were observed in transfectants expressing low LMP1 levels. Up-regulation of LMP1 by ZnSO4 treatment of the low LMP1 clone MTLM5 was accompanied by a slowing down of proliferation, increased cell clumping and decreased clonability. The results suggest that expression of LMP1 at levels which are compatible with immortalization of normal B-cells antagonizes the ability of BL cells to grow in vitro and in vivo, and illustrate a possible mechanism by which down-regulation of this viral antigen may favor tumorigenicity in EBV-carrying BLs.

Identification of target antigens for the human cytotoxic T cell response to Epstein-Barr virus (EBV): implications for the immune control of EBV-positive malignancies

Epstein-Barr virus (EBV), a human herpes virus with oncogenic potential, persists in B lymphoid tissues and is controlled by virus-specific cytotoxic T lymphocyte (CTL) surveillance. On reactivation in vitro, these CTLs recognize EBV-transformed lymphoblastoid cell lines (LCLs) in an HLA class I antigen-restricted fashion, but the viral antigens providing target epitopes for such recognition remain largely undefined. Here we have tested EBV-induced polyclonal CTL preparations from 16 virus-immune donors on appropriate fibroblast targets in which the eight EBV latent proteins normally found in LCLs (Epstein-Barr nuclear antigen [EBNA] 1, 2, 3A, 3B, 3C, leader protein [LP], and latent membrane protein [LMP] 1 and 2) have been expressed individually from recombinant vaccinia virus vectors. Most donors gave multicomponent responses with two or more separate reactivities against different viral antigens. Although precise target antigen choice was clearly influenced by the donor's HLA class I type, a subset of latent proteins, namely EBNA 3A, 3B, and 3C, provided the dominant targets on a range of HLA backgrounds; thus, 15 of 16 donors gave CTL responses that contained reactivities to one or more proteins of this subset. Examples of responses to other latent proteins, namely LMP 2 and EBNA 2, were detected through specific HLA determinants, but we did not observe reactivities to EBNA 1, EBNA LP, or LMP 1. The bulk polyclonal CTL response in one donor, and components of that response in others, did not map to any of the known latent proteins, suggesting that other viral target antigens remain to be identified. This work has important implications for CTL control over EBV-positive malignancies where virus gene expression is often limited to specific subsets of latent proteins.

Impaired long-term T cell immunity to Epstein-Barr virus in patients with nasopharyngeal carcinoma

The long-term T cell immunity to Epstein-Barr virus (EBV) is considered to play an important role in suppressing proliferation of EBV-infected B cells and outgrowth of EBV-associated tumors. It can be manifested and quantified by the EBV-induced focus regression assay. In the present study, we examined the strength of T cell immunity to EBV in patients with nasopharyngeal carcinoma (NPC) and other cancers originating from the head and neck region. In contrast to patients with other types of cancers, including EBV-negative NPC, patients with EBV-positive NPC were found to have a profound impairment in the long-term T cell immunity to EBV.

Clonal Epstein-Barr virus genome in T-cell-rich lymphomas of B or probable B lineage

Seventeen nodal lymphomas (originally diagnosed as T-cell lymphomas based on histological features and immunohistochemical staining results) were studied for the presence of Epstein-Barr virus (EBV) genome, and the results correlated with immunoglobulin and T-cell receptor gene rearrangement analyses performed on the same tissue samples. All four EBV positive cases had clonal rearrangement of the joining region of the immunoglobulin heavy chain (IgJH) gene without clonal T-cell receptor beta-chain (TCR beta) gene rearrangement. Of these, two cases also showed clonally rearranged light chain gene, and they were reclassified as T-cell rich B-cell lymphomas (TRBL). The other two cases lacked clonal kappa or lambda light chain rearrangement and they were reclassified as T-cell rich lymphomas of probable B lineage, based on their isolated IgJH clonal rearrangement. These B-cell lymphomas may be easily misdiagnosed as T-cell lymphomas owing to the presence of an abundant reactive T-cell infiltrate masking the tumor population. The florid T-cell reaction may represent an unusual host response towards a clonal proliferation of EBV bearing B cells.

Detection of Epstein-Barr virus in lymphocytic interstitial pneumonia by in situ hybridization

The involvement of Epstein-Barr virus (EBV) in the pathogenesis of lymphocytic interstitial pneumonia (LIP) was investigated using an in situ hybridization technique. Archival lung tissue samples from 14 patients (six men and eight women with a mean age of 58 +/- 3 yr) in whom a diagnosis of LIP had been previously established were retrospectively examined and compared with samples from 10 patients (six men and four women with a mean age of 58 +/- 3 yr) with idiopathic pulmonary fibrosis (IPF) who served as control subjects. In patients with LIP, the immunophenotype of the lymphocytic infiltrate was determined by using monoclonal antibodies to both pan-B-cell and pan-T-cell markers. In situ hybridization studies were performed by using the BamHI-W region of the EBV genome as a probe and a colorimetric detection method. The immunophenotyping studies showed that the interstitial infiltrate in LIP was primarily made up of B-lymphocytes, particularly within the lymphoid aggregates, whereas T-lymphocytes were sparsely distributed along the alveolar septa. The in situ hybridization studies showed the presence of cells bearing the EBV genome in nine cases of LIP and in two cases of IPF (p less than 0.05, Fisher's exact test). In LIP, the EBV-positive cells were observed in both enlarged and normal septa and occasionally within the lymphoid aggregates. We conclude that EBV may promote the proliferation of B-lymphocytes in a substantial number of patients with LIP.