IL-10 can induce the expression of EBV-encoded latent membrane protein-1 (LMP-1) in the absence of EBNA-2 in B lymphocytes and in Burkitt lymphoma- and NK lymphoma-derived cell lines

EBV-positive nasopharyngeal carcinoma and Hodgkin, T, and natural killer (NK) lymphomas express EBNA-1 and the latent membrane proteins (LMP1-2; type II latency). In contrast to type III EBV-transformed lymphoblastoid cell lines, in these cells the LMPs are expressed in the absence of EBNA-2. We have previously reported that exposure to CD40 ligand and IL-4 could induce LMP-1 in an in vitro EBV-infected Hodgkin lymphoma-derived cell line, which expressed only EBNA-1. We show now that both human and EBV-encoded IL-10 can induce LMP-1 in the absence of EBNA-2 in the Daudi, P3HR1, and other BL cell lines. Interestingly, induction of LMP-1 was not accompanied by the downregulation of BCL-6. IL-10 could also induce LMP-1 in the conditional lymphoblastoid cell line ER/EB2-5 where EBNA-2 was downregulated in the absence of estrogen. Moreover, IL-10 could induce the expression of LMP-1 in tonsillar B cells infected with the nontransforming, EBNA-2-deficient EBV strain P3HR1 and enhance LMP-1 expression in 2 EBV-positive NK lymphoma lines. The demonstration that IL-10 can induce the expression of LMP-1 in an EBNA-2-independent manner shows that the major transforming EBV gene LMP-1 can be induced by extracellular signals in lymphoid cells, and IL-10 might contribute to the establishment of type II EBV latency.     

Infection of HHV-8+ primary effusion lymphoma cells with a recombinant Epstein-Barr virus leads to restricted EBV latency,altered phenotype,and increased tumorigenicity without affecting TCL1 expression

To investigate the role of Epstein-Barr virus (EBV) in the pathogenesis of primary effusion lymphoma (PEL), we infected human herpesvirus 8 (HHV-8+) but EBV- PEL lines BC-3, CRO-AP/6, and CRO-AP/3 cells with the recombinant Akata EBV strain. All EBV-infected clones expressed EBER-1, EBNA-1, and LMP2A. The expression of LMP1 and LMP2B was variable. None, however, expressed EBNA2-6. The surface markers CD30, CD74, and syndecan-1 were down-regulated in EBV convertants. EBV-infected BC-3 and CRO-AP/6 cells were highly tumorigenic in severe combined immunodeficiency (SCID) mice in contrast to their respective EBV- parental cells. However, neither the parental cells nor the virus-converted counterparts expressed TCL1. The results showing that PEL cells on in vitro EBV infection do not sustain latency III despite the absence of immune pressure indicate that the choice of EBV latent gene expression program is cell dependent. The data suggest an important role of EBV in the pathogenesis of PEL.     

IL-21 imposes a type II EBV gene expression on type III and type I B cells by the repression of C- and activation of LMP-1-promoter

Epstein–Barr virus (EBV) is associated with a variety of human tumors. Although the EBV-infected normal B cells in vitro and the EBV-carrying B cell lymphomas in immunodeficient patients express the full set of latent proteins (type III latency), the majority of EBV-associated malignancies express the restricted type I (EBNA-1 only) or type II (EBNA-1 and LMPs) viral program. The mechanisms responsible for these different latent viral gene expression patterns are only partially known. IL-21 is a potent B cell activator and plasma cell differentiation-inducer cytokine produced by CD4⁺ T cells. We studied its effect on EBV-carrying B cells. In type I Burkitt lymphoma (BL) cell lines and in the conditional lymphoblastoid cell line (LCL) ER/EB2-5, IL-21 potently activated STAT3 and induced the expression of LMP-1, but not EBNA-2. The IL-21-treated type I Jijoye M13 BL line ceased to proliferate, and this was paralleled by the induction of IRF4 and the down-regulation of BCL6 expression. In the type III LCLs and BL lines, IL-21 repressed the C-promoter-derived and LMP-2A mRNAs, whereas it up-regulated the expression of LMP-1 mRNAs. The IL-21-treated type III cells underwent plasma cell differentiation with the induction of Blimp-1, and high levels of Ig and Oct-2. IL-21 might be involved in the EBNA-2-independent expression of LMP-1 in EBV-carrying type II cells. In light of the fact that IL-21 is already in clinical trials for the treatment of multiple malignancies, the in vivo modulation of EBV gene expression by IL-21 might have therapeutic benefits for the EBV-carrying malignancies.     

High expression of latent membrane protein 1 of Epstein-Barr virus and BCL-2 oncoprotein in acquired immunodeficiency syndrome-related primary brain lymphomas

Nearly all primary brain lymphomas in acquired immunodeficiency syndrome (AIDS) patients are associated withEpstein-Barr virus (EBV). The role of EBV in lymphomagenesis is not totally elucidated. One possible mechanism is the overexpression of the BCL-2 oncoprotein, because the latent membrane protein 1 (LMP1) has been reported to transactivate the bcl-2 gene in vitro. To study the interrelationship beetween LMP1 and BCL-2 in vivo, we have analyzed and compared their expression in 11 AIDS-related primary brain lymphomas and 57 AIDS- related systemic lymphomas by immunoperoxidase technique on frozen sections. In AIDS-related primary brain lymphoma, LMP1 and BCL-2 were expressed in all cases but 1. All positive cases exhibited morphologic immunoblastic features. In contrast, the only negative case was histologically close to Burkitt's lymphoma. In systemic lymphomas, LMP1 was expressed in 21 cases, whereas BCL-2 was positive in only 3 cases, all of which were extranodal. These results indicate that, in addition to the histologic type, the role of EBV genes and BCL-2 expression in lymphomatous cells differ as a function of their localization. In AIDS- related primary brain lymphomas, this correlation between LMP1 and BCL- 2 overexpression may have a major implication in lymphomagenesis.     

Frequent latent Epstein-Barr virus infection of neoplastic T cells and bystander B cells in human immunodeficiency virus-negative European peripheral pleomorphic T-cell lymphomas

We investigated 81 cases of peripheral pleomorphic T-cell lymphoma (PMTCL) occurring in human immunodeficiency virus-negative Europeans for the presence of Epstein-Barr virus (EBV)-DNA through polymerase chain reaction (PCR) for the presence of EBV-encoded small nuclear RNAs (EBER) and immediate early mRNAs (Bam H-fragment, lower strand frame [BHLF]) by in situ hybridization (ISH) and for EBV-encoded latent membrane protein (LMP) and nuclear antigen 2 (EBNA2) by immunohistology (IH). EBER-ISH, which could be applied on all cases, showed an overall incidence of EBV-infected cells in 38 of 81 cases (47%) of PMTCL. These data could be confirmed by PCR, which produced congruent results in the cases with amplifiable DNA. By EBER-ISH, the virus was located in the tumor cells in 30 of the 38 EBV-positive cases, with the proportion of the infected cells ranging from 1% to 100%. In 18 of these cases and in the 8 cases without EBV-infected tumor cells, the virus was, respectively, either additionally or exclusively detectable in occasional nonmalignant lymphoid bystander cells. An LMP expression was observed in several of the EBER-expressing tumor cells in 18 cases, whereas EBNA2 was detectable only in one case, which also displayed signs of viral replication. Some nonmalignant EBV-infected B immunoblasts also expressed LMP in several cases. Primary cutaneous and enteropathy-associated PMTCL displayed less frequent EBV infection when compared with other extranodal or nodal manifestations.     

Detection of Epstein-Barr virus in Korean peripheral T-cell lymphoma

One hundred thirty-seven patients with peripheral T-cell lymphomas (PTL) were examined for the presence of Epstein-Barr virus (EBV) using in situ hybridization for EBV-encoded RNA (EBER) and Bam H-fragment, lower strand frame (BHLF) and immunohistochemical stain for latent membrane protein (LMP). EBER was detected in tumor cells in 79 cases (58%); 26/66 PTL, unspecified (39%), 3/4 AILD (75%), 47/51 angiocentric lymphomas (AL) (92%), and 3/13 anaplastic large cell lymphoma (ALCL) (23%) by Revised European-American Lymphoma (REAL) classification. EBER was detected in 17/36 nodal (47%) vs. 62/101 extranodal PTLs (61%); 21/24 nasal, 12/32 Waldeyer's ring, 9/13 gastrointestinal, and 20/32 skin and soft tissue PTL. AL was consistently associated with the highest frequency of EBER among the extranodal PTL: nose (19/20), GI tracts (3/3), skin (14/15), and Waldeyer's ring (11/14). In extranodal lymphomas, coagulative-type zonal necrosis was seen almost exclusively in AL and showed correlation with EBER-positivity (P < 0.01). LMP was detected in 24 among 107 cases tested (22%). No signal for BHLF was detected in 76 cases tested, implying absent or negligible incidence of lytic infection. In conclusion, high incidence of EBV was observed in PTL among Koreans, with predilection for angiocentric lymphomas and extranodal presentation, especially involving nose, skin, and gastrointestinal tract.     

Biological aspects of Epstein-Barr virus (EBV)-infected lymphocytes in chronic active EBV infection and associated malignancies

Most primary Epstein-Barr virus (EBV) infections are clinically inapparent, but occasionally EBV infection can cause acute infectious mononucleosis. EBV has been linked to a variety of hematologic and non-hematologic malignancies. Chronic active EBV (CAEBV) infection designates a recently identified EBV-associated syndrome characterized by a variety of serious hematological disorders, including malignant lymphoma. EBV was found to infect circulating T- and/or NK-cells in patients with CAEBV infection. These EBV-infected T- and/or NK-cells express EBNA-1, LMP-1, and LMP-2A, a type II form of EBV latency, which is also observed in nasopharyngeal carcinoma (NPC), Hodgkin's disease (HD), and peripheral T-cell lymphoma. CAEBV infections may thus represent a subset of EBV-associated T- and/or NK-cell lymphoproliferative disorders.     

Synergistic effect of Epstein-Barr virus and tumor promoters on induction of lymphoma and carcinoma in nude mice

Balb/c nude mice were subcutaneously transplanted with fetal nasopharyngeal mucosa infected with B95-8 Epstein-Barr virus (EBV). n-Butyrate and/or 12-O-tetradecanoylphorbol 13-acetate (TPA) were injected subcutaneously on the third day and once a week thereafter. About 10 days later, tumor masses gradually grew in these mice. Histopathological examination was carried out 15 weeks later. Three cases of lymphomas (two T cell lymphomas and one B cell lymphoma) were observed in the group receiving EBV and TPA, and one T cell lymphoma and three cases of undifferentiated carcinoma were found in the group receiving EBV, TPA and n-butyrate, but no case was found in the control groups that were transplanted with fetal nasopharyngeal tissue infected with EBV, or TPA and n-butyrate alone. Polymerase chain reaction amplification and in situ hybridization revealed that lymphoma and carcinoma cells contained the EBV LMP1 and EBERs genes. LMP1 protein was also found in the carcinoma. The T and B cell lymphomas and the nasopharyngeal carcinoma in nude mice were derived from human nasopharyngeal mucosa; this was proved by using human specific monoclonal antibodies to CD3 for T cells, to CD20 for B cells, and to epithelial membrane antigen for epithelial cells. Nucleotide sequence analysis indicated that the homologies of EBV LMP1 genes in the induced malignant lymphomas and undifferentiated carcinomas to the B95-8 cell gene were around 96% and 99% respectively. The results showed that EB virus can infect nasopharyngeal mucosa of the human fetus and consequently induce malignant transformation by the synergistic effect of the tumor promoters, and that EBV DNA can persist in the lymphomas and carcinomas. Received: 6 April 1998 / Accepted: 25 June 1998     

Rescue of "crippled" germinal center B cells from apoptosis by Epstein-Barr virus

Epstein-Barr virus (EBV) is associated with B-cell lymphomas such as Hodgkin lymphoma, Burkitt lymphoma, and post-transplantation lymphoma, which originate from clonal germinal center (GC) B cells. During the process of somatic hypermutation, GC B cells can acquire deleterious or nonsense mutations in the heavy and light immunoglobulin genes. Such mutations abrogate the cell surface expression of the B-cell receptor (BCR), which results in the elimination of these nonfunctional B cells by immediate apoptosis. EBV encodes several latent genes, among them latent membrane protein 1 (LMP1) and LMP2A, which are regularly expressed in EBV-positive Hodgkin lymphoma and posttransplantation lymphomas. Since LMP1 and LMP2A mimic the function of 2 key receptors on B cells, CD40 and BCR, respectively, we wanted to learn whether EBV infection can rescue proapoptotic GC B cells with crippling mutations in the heavy chain immunoglobulin locus from apoptosis. We show here that BCR-negative GC B cells readily enter the cell cycle upon infection with EBV in vitro and yield clonal lymphoblastoid cell lines that are incapable of expressing a functional BCR because the rearranged and formerly functional heavy chain immunoglobulin alleles carry deleterious mutations. Our findings imply an important role for EBV in the process of lymphomagenesis in certain cases of Hodgkin lymphoma and posttransplantation lymphomas.     

EBV infection patterns in Hodgkin''s disease and normal lymphoid tissue: expression and cellular localization of EBV gene products

The present study was performed to clarify the reported inconsistencies regarding the frequency of the association of Epstein-Barr virus (EBV) and Hodgkin's disease (HD). Biopsies from 102 patients with HD were screened for the presence of EBV-encoded small nuclear RNA (EBER) and latent membrane protein (LMP) by using a non-isotopic in situ hybridization (ISH) and immunohistology (IH), respectively. The results were additionally compared with those obtained by polymerase chain reaction (PCR) for EBV-DNA detection. EBV was detected by EBER-ISH in 67% of the HD cases and in 25% of the control group cases consisting of normal lymph nodes. The results of PCR performed on cases with amplifiable DNA were overall congruent with those obtained by EBER-ISH. With respect to the cellular localization of EBV, four categories of HD could be established: (a) cases with EBV-infected tumour cells (42/102), (b) cases with additional infection of bystander cells (4/102); (c) cases with EBV infection restricted to non-malignant bystander cells (23/102); and (d) cases with neither EBV-infected tumour cells nor bystander cells (33/102). LMP expression was detectable only in the neoplastic cell population of those cases with EBER-positive tumour cells, suggesting a frequent involvement of EBV in the pathogenesis of HD.     

Epstein-Barr virus in benign lymph node biopsies from individuals infected with the human immunodeficiency virus is associated with concurrent or subsequent development of non-Hodgkin's lymphoma.

Individuals infected with the human immunodeficiency virus (HIV) have an increased incidence of high-grade B-cell lymphoma. In many instances, these lymphomas contain Epstein-Barr viral (EBV) genomes. To investigate the role of EBV in development of HIV-related lymphoma, benign fixed lymph node biopsies from normal individuals and HIV-infected individuals with persistent generalized lymphadenopathy (PGL) were analyzed for EBV sequences by polymerase chain reaction and in situ DNA hybridization techniques. EBV DNA was not detected in any of 16 benign lymph node biopsies from normal individuals, but could be detected from 13 of 35 PGL biopsies. The EBV-infected cells were present in both follicular and interfollicular areas and in both small and large lymphoid cells. The presence of detectable amounts of EBV DNA in the 13 PGL biopsies was associated with an increased incidence of concurrent lymphoma at another site (n = 3) or development of lymphoma in time (n = 2). In contrast, only 1 of 22 individuals with EBV-negative PGL biopsies developed lymphoma in time (P less than .05). EBV was detected in all five lymphomas in which tissue was available for subsequent analysis, including the lymphoma that developed in the individual without EBV in his previous PGL biopsy. These findings support the hypothesis that EBV plays a role in development of some HIV-related lymphomas. Detectable EBV lymphoproliferations occur in a few PGL biopsies and are associated with a significant risk of EBV DNA-positive non-Hodgkin's lymphoma.     

Presence of Epstein-Barr virus and strain type assignment in Argentine childhood Hodgkin's disease

Epstein-Barr virus (EBV) has been implicated in the etiology of a large number of malignancies. Most recently several studies have linked EBV to Hodgkin's disease. In this report, formalin-fixed, paraffin-embedded tissues were collected retrospectively from 41 children with Hodgkin's disease treated at our hospital. Lymph node biopsies were examined for the presence of two virus-encoded latent proteins: latent membrane protein (LMP) and Epstein-Barr nuclear antigen-2 (EBNA-2), in Reed- Sternberg (RS) and Hodgkin (H) cells, by peroxidase immunolabeling. Nonisotopic Epstein-Barr encoded RNAs (EBERs) in situ hybridization was also performed and positive labeling in malignant cells was detected. Twenty specimens were EBER+/LMP+, 2 were EBER+/LMP-, and 19 were EBER- /LMP-. However, none of the 41 cases expressed EBNA-2. Twenty-two of 41 (54%) cases were EBV positive including 2 of 6 with lymphocyte predominance, 19 of 25 with mixed cellularity, 0 of 9 with nodular sclerosis, and 1 of 1 with lymphocyte depletion. In the age range of 2 to 6 years, 14 of 17 (82%) samples were EBV-positive, whereas only 8 of 24 (33%) samples from the age range of 7 to 15 years contained EBV. (P = .004), a two-tailed Fisher's test). In 17 samples, polymerase chain reaction amplification was performed using strain specific primers for exon sequences of the EBNA-3C gene of EBV. From 12 positive samples, 8 contained EBV-A and 4 EBV-B. These results support the hypothesis that EBV contributes to the pathogenesis of pediatric Hodgkin's disease, particularly in mixed cellularity Hodgkin's disease and in the younger group.     

Expression of the Epstein–Barr virus latent membrane protein 1 induces B cell lymphoma in transgenic mice

The latent membrane protein 1 (LMP1) of the Epstein–Barr virus has transforming properties in rodent fibroblasts and is expressed in most of the cancers associated with Epstein–Barr virus (EBV) infection including posttransplant lymphomas, Hodgkin’s disease, nasopharyngeal carcinoma, and AIDS-related lymphomas. In this study, three lineages of LMP1 transgenic mice were established with LMP1 expressed under the control of the Ig heavy chain promoter and enhancer. Lymphoma developed in all three lineages, and the incidence of lymphoma increased significantly with age with lymphomas developing in 42% of transgenic mice over 18 months. The expression of LMP1 was detected at high levels in the lymphoma tissues but only at trace levels in normal lymphoid tissues. Gene rearrangement of the Ig heavy chain indicated monoclonality or oligoclonality in all lymphomas, some of the lymphoid hyperplastic spleens, and some histologically normal spleens. These data reveal that LMP1, without the expression of other EBV genes, is oncogenic in vivo and indicate that LMP1 is a major contributing factor to the development of EBV-associated lymphomas.     

Common cytological and cytogenetic features of Epstein-Barr virus (EBV)-positive natural killer (NK) cells and cell lines derived from patients with nasal T/NK-cell lymphomas,chronic active EBV infection and hydroa vacciniforme-like eruptions

In this study, we describe the cytological and cytogenetic features of six Epstein-Barr virus (EBV)-infected natural killer (NK) cell clones. Three cell clones, SNK-1, -3 and -6, were derived from patients with nasal T/NK-cell lymphomas; two cell clones, SNK-5 and -10, were isolated from patients with chronic active EBV infection (CAEBV); and the other cell clone, SNK-11, was from a patient with hydroa vacciniforme (HV)-like eruptions. An analysis of the number of EBV-terminal repeats showed that the SNK cell clones had monoclonal EBV genomes identical to the original EBV-infected cells of the respective patients, and SNK cells had the type II latency of EBV infection, suggesting that not only the cell clones isolated from nasal T/NK-cell lymphomas but also those isolated from CAEBV and HV-like eruptions had been transformed by EBV to a certain degree. Cytogenetic analysis detected deletions in chromosome 6q in five out of the six SNK cell clones, while 6q was not deleted in four control cell lines of T-cell lineage. This suggested that a 6q deletion is a characteristic feature of EBV-positive NK cells, which proliferated in the diseased individuals. The results showed that EBV-positive NK cells in malignant and non-malignant lymphoproliferative diseases shared common cytological and cytogenetic features.     

Detection of Epstein-Barr virus and human T-cell lymphotropic virus type 1 in malignant nodal lymphoma, studied in Okinawa, a subtropical area in Japan

Formalin-fixed paraffin-embedded lymph node samples were collected from 100 cases of malignant nodal lymphoma documented in Okinawa in the period from 1973 through 1998. According to the new World Health Organization classification, 12 cases were Hodgkin's lymphoma (HL). Eighty-eight cases of non-Hodgkin's lymphoma (NHL) included 54 cases of T-cell type and 34 cases of B-cell type. Using polymerase chain reaction (PCR), Epstein-Barr virus (EBV) was detected in 11 cases (91.7%) of HL and in 57 cases (64.8%) of NHL, and human T-cell lymphotropic virus type 1 (HTLV-1) was detected in 23 cases (26.1%) of NHL. Clonal integration of HTLV-1 was detected in 10 (43.5%) of 23 HTLV-1 PCR-positive cases by the inverse PCR technique. The EBV-infected cells were detected by EBER-1 in situ hybridization in 11 (91.7%) of 12 HL cases and in 64 (72.7%) of 88 NHL cases. Irrespective of phenotype and tissue type of the malignant lymphoma, the rate of EBV-positive infection in Okinawa was higher than that in any other districts reported in Japan. This characteristic high rate of EBV-positive infection in Okinawa can be ascribed to various factors, such as racial and geographical differences.     

Epstein-Barr virus nuclear antigen 2 specifically induces expression of the B-cell activation antigen CD23.

Epstein-Barr virus (EBV) infection of EBV-negative Burkitt lymphoma (BL) cells induces some changes similar to those seen in normal B lymphocytes that have been growth transformed by EBV. The role of individual EBV genes in this process was evaluated by introducing each of the viral genes that are normally expressed in EBV growth-transformed and latently infected lymphoblasts into an EBV-negative BL cell line, using recombinant retrovirus-mediated transfer. Clones of cells were derived that stably express the EBV nuclear antigen 1 (EBNA-1), EBNA-2, EBNA-3, EBNA-leader protein, or EBV latent membrane protein (LMP). These were compared with control clones infected with the retrovirus vector. All 10 clones converted to EBNA-2 expression differed from control clones or clones expressing other EBV proteins by growth in tight clumps and by markedly increased expression of one particular surface marker of B-cell activation, CD23. Other activation antigens were unaffected by EBNA-2 expression, as were markers already expressed on the parent BL cell line, including BL markers (cALLA and BLA), proliferation markers (transferrin receptor and BK19.9), and cell adhesion-related molecules (LFA-1 and LFA-3). Increased CD23 expression in cells expressing EBNA-2 was apparent from monoclonal anti-CD23 antibody binding to the cell surface, from immunoprecipitation of the 45-kDa and 90-kDa CD23 proteins with monoclonal antibody, and from RNA blots probed with labeled CD23 DNA. The results indicate that EBNA-2 is a specific direct or indirect trans-activator of CD23. This establishes a link between an EBV gene and cell gene expression. Since CD23 has been implicated in the transduction of B-cell growth signals, its specific induction by EBNA-2 could be important in EBV induction of B-lymphocyte transformation.