Epstein–Barr virus in Reed–Sternberg G-like cells in non Hodgkin's lymphomas

In the course of our study on Hodgkin's disease (HD), ten cases of non-Hodgkin's lymphomas (NHL) containing Hodgkin and Reed-Sternberg-like (MRS) cells were encountered. Many of these cases had initially been diagnosed as HD, but on careful review of the histology, with the aid of immunophenotyping studies, they were reclassified as NHL. The presence of Epstein–Barr virus (EBV) in these HRS-like cells was investigated using a combination of EBER in situ hybridization (ISH) and immunostaining for the detection of EBV-encoded latent membrane protein (LMP). HRS-like cells in four cases (two lymphoplasmacytoid lymphomas, one Richter's transformation of lymphoplasmacytoid lymphoma, and one immunoblastic lymphoma of T-cell type) were found to be EBV-positive. In two of these cases, a second biopsy taken up to 10 years later also contained EBV in the HRS-like cells. In three of the four cases, HRS-like cells expressed the activation antigen CD30, but the expression of B- or T-cell antigens was variable. All cases of T-cell-rich B-cell lymphomas were negative for EBV. In conclusion, EBV may play a role in the development of HRS-like cells i some cases of NHL. The relationship of HRS-like cells to HRS cells of HD is discussed.     

Decreased expression of cellular markers in Epstein-Barr virus-positive Hodgkin's disease

Epstein-Barr virus (EBV) has been demonstrated in the Reed–Stenberg cells and their mononuclear variants (Hodgkin cells; H-RS cells) in a substantial number of Hodgkin's disease (HD) cases. Moreover, EBV can modulate both in vivo and in vitro the expression of several cellular genes, including lymphoid differentiation markers. Therefore we investigated, in 64 cases of HD, the relationship between the presence of EBV and the expression of lymphoid (CD45RB), T- (CD3, CD45RO), B- (CD20, MB2 antigen, CDw75), and myeloid-cell lineage markers (CD15), and of activation markers (CD30, EMA, and the 115D8 antigen) on the H-RS cells. EBV-positive cases, as demonstrated by the presence of EBER-1 and -2 RNA and LMP-1 protein expression, showed a significant reduction in the expression on H-RS cells of T-cell lineage (CD3, p<0·02), B-cell lineage (CD20, P<0·005), AND ACTIVATION MARKERS (ema; P<0·002 and the 115D8 antigen; P<0·001) as compared with EBV-negative cases. No differences were found in the expression of CD15, CD30, CD45RO, CD45RB CDw75, or the MB2 antigen on H-RS cells in EBV-positive and EBV-negative HD cases. Interestingly, in 11 cases of EBV-negative HD, B-as well as T-cell lineage markers could be found on some H-RS cells. These data suggest that EBV in H-RS cells is able to down-regulate the expression of T- (CD3) and B- (CD20) cell lineage markers and lymphoid activation markers (EMA and the 115D8 antigen). For this reason, the origin of H-RS cells in HD, as studies by immunohistochemistry, cannot be discussed without taking into account the presence of EBV.     

Correlation of the expression of Epstein-Barr virus latent membrane protein and in situ hybridization with biotinylated BamHI-W probes in Hodgkin''s disease.

The detection of Epstein-Barr virus (EBV) nucleic acids by in situ hybridization (ISH) with biotinylated BamHI-W probes was correlated with the expressions of EBV latent membrane protein (LMP) and EB nuclear antigen 2 (EBNA2), in 107 cases of Hodgkin's disease (HD) of different immunomorphologic subtypes. Epstein-Barr virus nucleic acids were present and restricted to the pathogenic cells in 4 of 40 (10%) cases of nodular sclerosis (NS) and 33 of 55 (60%) cases of mixed cellularity (MC), but were undetectable in other subtypes. Of the 37 cases positive for EBV nucleic acids, 35 (95%) showed the expression of LMP. Epstein-Barr virus nucleic acids and LMP were restricted to Reed-Sternberg cells and variants. Only 1 case (MC) showed LMP expression in the absence of EBV detection. The correlation was strengthened by the finding of LMP expression at first diagnosis in 6/7 EBV positive cases at relapse (14-126 months) (5/5 EBV negative cases at relapse were LMP negative at first diagnosis). EBNA2 was absent in all 13 (NS, 2; MC, 11) EBV+ and LMP+ cases tested. Both LMP and EBNA2 were expressed in control EBV-positive tissues and cell lines. EBV serology in MC HD was indicative of latent EBV infection, but neither serology nor clinical parameters correlated with the presence or the absence of EBV, over a short-term follow-up (median, 20 months). The findings, although not proving EBV as the etiologic agent of HD, suggest that: 1) LMP expression alone may be adequate for identifying EBV-associated HD, 2) the MC subtype has a stronger relation with EBV presence, and 3) the regulation of EBV genes in HD is different from other EBV-associated disorders. The clinical implications still remain to be discovered.     

Expression of Epstein-Barr virus replicative proteins in AIDS-related non-Hodgkin's lymphoma cells.

Epstein-Barr virus (EBV) infection in lymphoproliferative lesions has been assumed to be strictly latent. In order to investigate the possible occurrence of EBV replication in AIDS-related lymphoma (ARL) cells, we studied 13 cases by immunohistology using monoclonal antibodies to the EBV-encoded switch-protein BZLF1, early antigens (EAs), late replicative proteins [virus capsid antigens (VCAs) and membrane antigens (MAs)], and to the latent proteins EB nuclear antigen 2 (EBNA 2) and latent membrane protein (LMP). EBV genomes were detected by in situ hybridization. EBV genomes and/or gene products were demonstrated in ten cases, including all immunoblast-rich lymphomas, two Burkitts lymphomas, and a T-cell anaplastic large-cell lymphoma. The BZLF1 protein, which disrupts latency in B cells, was identified in six (60 per cent), and EAs in four (40 per cent) of the EBV-positive ARL. Only one lymphoma (10 per cent) expressed VCAs and MAs. EBNA 2 and LMP were detected in three (30 per cent) and eight (80 per cent) of EBV-positive cases, respectively. EBV DNA was detected in lymphoma cells in 7 of 12 (58 per cent) cases. The most important finding of this study was frequent spontaneous activation of latent EBV in ARL. Production of complete virus, however, was either aborted, or tumour cells expressing late productive cycle proteins (VCA, MA) were rapidly cleared from tissues. It is suggested that host factors that normally inhibit replication of EBV are deficient in AIDS patients.     

Presence of Epstein-Barr virus harbouring small and intermediate-sized cells in Hodgkin'S disease. Is there a relationship with Reed-Sternberg cells?

Forty-four cases of Hodgkin's disease (HD), mostly of the nodular sclerosing type, were investigated for the presence of Epstein-Barr virus (EBV) by polymerase chain reaction (PCR) and DNA and RNA in situ hybridization (DISH, RISH), as well as by immunohistochemistry for the detection of latent membrane protein-1 (LMP-1) of EBV. in situ hybridization (ISH) was combined with immunohistochemistry to correlate the presence and activity of the virus at the cellular level. In 18/34 (53 per cent) cases, EBV-DNA sequences could be detected with the PCR method. In 12/18 positive cases, DISH and RISH were also positive. In the remaining six EBV-PCR positive cases, two were also positive with RISH and LMP-1, whereas no positive signal with DISH could be obtained. All DISH and/or RISH positive cases were also positive for LMP-1. With RISH, not only the Reed-Sternberg cells and their mononuclear variants (RS cells) stained positive, but also small and intermediate cells frequently reacted with the EBV-specific probes (EBER-1 and -2). Double staining with cellular markers (CD3, CD20, CD45, CD45RO, CD68, and the lectin PNA) revealed that most of the smaller EBER-positive cells frequently did not express T, B, or histiocytic markers, but that they, as well as the RS cells, showed cytoplasmic and membranous staining with PNA. These smaller EBER-positive cells were not found in EBV-PCR negative HD. EBER-positive RS cells were almost always LMP-1 positive, as well as a substantial proportion of the intermediate-sized cells, whereas the majority of the small EBER-positive cells remained LMP-1 negative. In EBV-PCR positive non-malignant lymph nodes, only a few EBER-1 and -2 positive cells could be observed. As in infectious mononucleosis, these cells frequently expressed the B-cell marker CD20. Although we cannot exclude the fact that the majority of the smaller EBV-positive cells in HD belong to reactive EBV-infected lymphocytes, our data favour the hypothesis that at least some of these smaller cells may belong to the reservoir of neoplastic cells in HD.     

Characterization of natural Epstein-Barr virus infection and replication in smooth muscle cells from a leiomyosarcoma

Cells from a leiomyosarcoma tumor (LMS-1) from a patient with the acquired immunodeficiency syndrome (AIDS) were explanted, cultured in vitro, and studied by phase-contrast microscopy for morphologic and growth characteristics, immunostaining for cell markers, EBER in situ hybridization and polymerase chain reaction for detection of Epstein-Barr virus (EBV), and immunostaining for expression of EBV antigens. The cells exhibited very slow growth in vitro, with unusual elliptical and spindle-shaped morphology and fragmentation of the cytoplasm into long, tapering, cytoplasmic processes. Greater than 90% of cells expressed diffuse distribution of the smooth muscle isoform of actin by immunoperoxidase staining. Approximately 25% of cells expressed very bright fluorescence by immunostaining of the smooth muscle isoforms of calponin and actin. The majority of cells demonstrated a weak signal for CD21; approximately 5–10% of cells showed a strong signal that was confined to cell surfaces. The cultured cells harbored EBV, and infectious EBV continued to be detected by polymerase chain reaction and virus culture through several passages in vitro. Several EBV antigens were expressed, including latent antigen EBNA-1, immediate-early antigen BZLF1, early antigen EA-D, and late antigens, including viral capsid antigen p160, gp125, and membrane antigen gp350. Human umbilical cord lymphocytes that were transformed with virus isolated from cultured cells yielded immortalized cell lines that expressed EBV antigens similar to other EBV-transformed lymphocyte cell lines. These results confirm that EBV is capable of lytic infection of smooth muscle cells with expression of a repertoire of latent and replicative viral products and production of infectious virus. EBV infection of smooth muscle cells may contribute to the oncogenesis of leiomyosarcomas. J. Med. Virol. 57:36–46, 1999. © 1999 Wiley-Liss, Inc.     

Expression of T-cell antigens on Reed-Sternberg cells in a subset of patients with nodular sclerosing and mixed cellularity Hodgkin's disease

Expression of T-cell antigens by Reed-Sternberg (RS) cells has not been detected in most studies of Hodgkin's disease (HD). The authors employed an improved method of fixation (paraformaldehyde-lysine-periodate), which sharply defined cell borders and revealed T-cell antigens on RS cells in 8 of 30 (27%) cases of HD. Antigen-specific staining was confirmed by immunoelectron microscopy. RS cells expressed T11 (8/8 cases), Leu-3 or T4 (4/8 cases), Leu-4 or T3 (3/8 cases), but not other T-cell specific antigens (Leu-1, T8, T6, 3A1). RS cells were negative for leukocyte common antigen (LCA/T200), in contrast to positive LCA/T200 staining of RS-like cells in T-cell lymphomas. RS cells in all HD cases were positive for Ki-1 and/or Leu-M1 antigens. The percentage of RS cells expressing T-cell antigens was less than 20% (2 cases), 20-50% (3 cases), or greater than 50% (3 cases). This percentage and the specific T-cell antigens expressed varied in tissues from different sites in each of 2 cases. Expression of T-cell antigens by RS cells was found in nodular sclerosis (6 of 20 cases) and mixed cellularity (2 of 5 cases) but not in lymphocyte predominance (2 cases), lymphocyte depletion (1 case), or unclassified types (2 cases). Two cases of nodular sclerosis contained areas of necrosis surrounded by sheets of lacunar cells (syncytial variant of NSHD). Two other cases were associated with cutaneous lymphoma. One of these cases was mixed cellularity HD, which appeared to be confined to the skin. In a second case, tumor cells of similar phenotype (T4+, Ki-1+) were found in skin and lymph nodes of a patient with coexistent mycosis fungoides and HD. These results are consistent with an origin of RS cells from T cells in some cases of nodular sclerosing and mixed cellularity HD. They also suggest that the same cell type, an activated helper T-cell, is involved in the pathogenesis of both skin lesions and lymphadenopathy of some patients with coexistent mycosis fungoides and HD.     

Modulation of interleukin-6 expression in Hodgkin and Reed–Sternberg cells by Epstein–Barr virus

Variable proportions of Hodgkin's disease (HD) cases are associated with the Epstein–Barr virus (EBV), but the role of EBV in HD is not entirely clear. Hodgkin and Reed–Sternberg (HRS) cells of EBV-associated HD are characterized by expression of the EBV gene product LMP1. In other cellular environments, LMP1 has been shown to induce interleukin (IL)-6. In this study, 105 HD cases were tested for differences in IL-6 expression among LMP1-positive and -negative cases. Isotopic in situ hybridization and correlation with the presence of EBV gene products revealed significantly higher proportions of cases with IL-6-expressing tumour cells in LMP1-positive (31 of 37, 84 per cent) as compared with LMP1-negative HD cases (35 of 68, 51 per cent). Thus, although not exclusive to EBV-positive HRS cells, IL-6 expression appears to be upregulated in EBV-associated HD. IL-6 receptor (CD126) expression was tested by in situ hybridization and found in a broad spectrum of cell types, regularly including HRS cells. Superinduction of IL-6 expression may be among the mechanisms by which EBV confers a growth advantage on virus-infected HRS cells and by which the virus may contribute to the morphological and clinical peculiarities of HD. © 1997 John Wiley & Sons, Ltd.     

Epstein-Barr virus infection and bcl-2 proto-oncogene expression. Separate events in the pathogenesis of Hodgkin's disease?

The present study was undertaken to investigate whether Epstein-Barr virus-(EBV) encoded latent membrane protein (LMP) induces the expression of BCL-2 in Hodgkin and Reed-Sternberg (HRS) cells of Hodgkin's disease (HD) and thereby provide a possible mechanism for the role of EBV in the pathogenesis of this disease. Fifty-three cases of HD were studied for the presence of EBV using EBV-encoded RNA in situ hybridization and LMP immunohistochemistry. Immunostaining for BCL-2 on paraffin material was performed using microwave treatment of tissue sections before the application of the primary monoclonal antibody. EBV was located in HRS cells in 16 cases (30%). All cases that were EBV-encoded RNA in situ hybridization positive, also expressed LMP. BCL-2 expression in HRS cells was detected in 16 cases (30%), but only two of these were also EBV-positive. In both of these cases, only occasional HRS cells expressed BCL-2, in contrast to LMP, which was detected in nearly all such cells. BCL-2 staining was predominantly cytoplasmic with some membrane pattern. These results demonstrate that BCL-2 expression can be detected in HRS cells in routinely processed HD tissue and that whereas EBV does not induce the expression of BCL-2 in HD, BCL-2 may have a role in the pathogenesis of EBV-negative cases of HD.     

Expression of Epstein-Barr virus genes and of lymphocyte activation molecules in undifferentiated nasopharyngeal carcinomas.

Previous studies investigating the role of Epstein-Barr virus (EBV) in undifferentiated nasopharyngeal carcinoma (NPC) have been performed on extracts from biopsies. The authors analyzed expression and localization of viral gene products in 18 undifferentiated NPCs at the cellular level using immunohistology and in situ hybridization. All cases were EBV-positive. The small nuclear EBV-encoded RNAs, EBERs, were regularly expressed whereas the latent membrane protein, LMP1, and EBV was detectable only in four cases (22%) and the nuclear antigen 2 was not detectable. The BZLF-1 protein of EBV which disrupts viral latency, was not detectable, confirming that the virus is latent in the tumor cells. Although the expression of the CD23 antigen in transplantable NPCs has been reported, our study demonstrates that expression of this antigen in human undifferentiated NPCs is rare. In contrast, almost all cases expressed the CDw70 antigen. Since in normal tissues this antigen is present only in activated lymphoid blasts, this finding may be relevant for the differential diagnosis of undifferentiated NPCs.     

Inconsistency of the immunophenotype of Reed-Sternberg cells in simultaneous and consecutive specimens from the same patients. A paraffin section evaluation in 56 patients.

Both immunophenotypic overlaps between Hodgkin's disease (HD) and non-Hodgkin's lymphoma (NHL), and evolution of one into the other have been reported. However, the underlying assumption that the antigenic expression of Reed-Sternberg (RS) cells is consistent in the same patient has not been evaluated. Such an evaluation was undertaken by immunophenotyping paraffin-embedded lymphoid tissue biopsies with HD from 56 patients in whom multiple specimens were obtained, either simultaneously from different sites or at different times. The panel of antibodies we used included: CD3 polyclonal antiserum, DAKO-M1 (CD15), L26 (CD20), BerH2 (CD30), MT1 (CD43), DAKO-LCA (CD45RB), UCHL1 (CD45R0), LN2 (CD74), and DAKO-EMA. The phenotype of RS cells was identical in simultaneous biopsies in only 11 of 39 patients (28%) and remained constant in consecutive biopsies in only 4 of 21 patients (19%). Major differences (relative to cell lineage specific antigens) were observed in 10 of 39 patients with simultaneous biopsies and in 10 of 21 patients over time; they mainly involved expression of T-cell antigens. Minor differences (relative to any other antigen) were observed in 22 of 39 patients with simultaneous biopsies and in 15 of 21 patients over time; these mainly involved CD15 or CD74. This striking variability of the immunophenotype of RS cells in the same patient may be due to aberrant marker expression, as a result of the neoplastic state, and/or to modulation of antigenic expression in relation to the host environment. This inconsistency suggests caution when interpreting the relationship between HD and NHL by paraffin immunophenotyping alone.     

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.     

Diagnostic accuracy of imprint cytology in the assessment of Hodgkin's disease in Japan

Our objective was to evaluate the usefulness of cytomorphologic assessment in the accuracy of diagnosis of Hodgkin's disease (HD), using imprint cytological preparations over a 18-yr period. Imprint materials from 34 HD cases were reviewed using cytomorphological and immunocytochemical studies. Twenty-six cases (76.5%) were diagnosed to be HD and 6 cases (17.6%) were suspected to be HD, but 2 cases (5.9%) were cytologically diagnosed as reactive lesions, because of an insufficient number of Reed-Sternberg (RS) cells. The 6 suspected cases were definitively diagnosed as HD, using immunocytochemistry. Immunophenotyping of RS cells in 32 cases (excluding the two cases of reactive lesions) showed CD30+ in 31 (96.9%) cases, CD15+ in 22 (68.8%) cases and CD20+ in 12 (37.5%) cases. RS cells were immunophenotypically classified into five groups: A, (CD 30+, 15+, 20-) 15 (46.9%); B, (CD30+, 15-, 20-) 5 (15.6%); C, (CD 30+, 15+, 20+) 6 (18.8%); D, (CD30+, 15-, 20+) 5 (15.6%); and E, (CD30-, 15+, 20+) 1 (3.1%). Cytomorphologic differences in RS cells were identified between group D and other groups (CD15+ and/ or CD20-). The former had a low polymorphic shape (like popcorn), and the latter had a more classical polymorphic shape. Epstein-Barr virus (EBV)-latent membrane protein-1(LMP-1) was identified in 16 (50%) cases. LMP-1 expression was found not only in classic RS cells, but also in smaller variants. These variants did not match the morphologic criteria of RS cells, but expressed the common phenotype (CD30+, CD15+/-) of RS cells, suggesting the same cellular origin as RS cells. This study demonstrated that imprint cytology from lymph node biopsies can be a useful tool for the diagnosis and the evaluation of the cellular biology of HD.     

Expression of B7 (CD80) and CD40 antigens and the CD40 ligand in Hodgkin's disease is independent of latent Epstein-Barr virus infection

Aim-To examine the expression of CD40 and B7 (CD80) antigens and the CD40 ligand in Hodgkin's disease.Methods-Antigen and ligand expression was studied in 17 cases of Hodgkin's disease using immunohistochemistry. The study included 11 cases of Hodgkin's disease in which latent Epstein-Barr virus (EBV) infection could be demonstrated within tumour cells by in situ hybridisation for the EBV encoded early RNAs (EBERs).Results-In all cases, irrespective of EBV status, Reed-Sternberg cells and their variants (HRS cells) showed strong expression of both B7 and CD40 antigens. CD40 ligand expression was not shown in HRS cells but was confined to a subset of small lymphocytes some of which were seen to be in intimate contact with HRS cells.Paraffin wax sections from a further 60 cases of Hodgkin's disease were examined for CD40 and EBER expression alone. The CD40 antigen was identified in HRS cells in all of these cases irrespective of EBER expression.Conclusions-As CD40 and B7 expression are features of professional antigen presenting cells, these results provide further evidence that HRS cells may have antigen presenting properties and that this may contribute to the characteristic recruitment and activation of non-malignant lymphocytes which is a feature of Hodgkin's disease. The ability of HRS cells to activate T(h) cells may in turn contribute to their own survival through the induction of the gp39/CD40 pathway.     

Rapid determination of Epstein-Barr virus latent or lytic infection in single human cells using in situ hybridization.

Epstein-Barr (EBV) virus is associated with malignancies such as lymphoma and carcinoma. Infection of cells with EBV may result in either lytic infection with production of viral particles, characterized by the presence of linear DNA forms, or latent infection, characterized by either episomal or integrated DNA forms. To examine whether the different lytic and latent EBV DNA forms can reliably be distinguished in single human cells, in situ hybridization was performed in EBV-positive cell lines. Immunocytochemistry and Southern blot analysis were performed supplementary to in situ hybridization. In latent infection, three in situ hybridization patterns were observed: large-disperse (episomal), small-punctate (integrated) and combined (both), signal types 1, 2 and 3 respectively. These were associated with expression of latent membrane protein 1, but not with Z fragment of Epstein-Barr replication activator or viral capsid antigen. In lytic infection, three additional in situ hybridization patterns were observed: nuclear membrane associated, bubble (filling up the nucleus) and spillover (covering the lysed cells) signals types 4, 5 and 6 respectively. Signal types 4 and 5 were associated with expression of latent membrane protein 1 and Z fragment of Epstein-Barr replication activator but not viral capsid antigen, whereas type 6 was associated with expression of viral capsid antigen only. Southern blot analysis confirmed these results; however, low copy numbers of integrated virus were often missed by Southern blot, confirming that in situ hybridization is more sensitive in determining the presence of all types of EBV DNA. In situ hybridization may prove useful in rapidly screening large series of tissue microarrays and other clinical specimens for the presence of lytic or latent EBV.     

Epstein-Barr virus infection in colorectal neoplasms associated with inflammatory bowel disease: detection of the virus in lymphomas but not in adenocarcinomas

Epstein-Barr virus (EBV) is associated with several lymphoid and epithelial human malignancies. The latter include gastric adenocarcinomas, while sporadic colorectal adenocarcinomas (CRCs) have been reported to be EBV-negative. Recently, increased numbers of EBV-infected B lymphocytes have been detected in intestinal mucosal samples affected by ulcerative colitis (UC) and, to a lesser extent, Crohn's disease (CD). Both CRC and colorectal non-Hodgkin's lymphoma (NHL) are recognized complications of inflammatory bowel disease (IBD), but it is unclear to what extent EBV contributes to the development of these neoplasms. Seventeen cases of IBD-associated CRC and nine cases of IBD-associated colorectal NHL were therefore studied for the presence of EBV by in situ hybridization. EBV-positive cases were further studied for the expression of the EBV-encoded nuclear antigen (EBNA) 2 and the latent membrane protein (LMP) 1 of EBV by immunohistochemistry. Four out of seven cases of colorectal NHL associated with UC were shown to be EBV-positive. In addition, two of two colorectal NHLs developing in patients with CD were EBV-positive. Of the EBV-positive lymphomas, three displayed a pattern of EBV latent gene expression consistent with type I latency (EBNA2(-)/LMP1(-)), two a type II pattern (EBNA2(-)/LMP1(+)), and one a type III pattern (EBNA2(+)/LMP1(+)). These findings suggest that EBV infection is involved in the pathogenesis of a proportion of colorectal NHLs developing in IBD. Iatrogenic immunosuppression may contribute to the development of these lymphomas. By contrast, all 17 IBD-associated CRCs were EBV-negative, including a case of CRC occurring synchronously with an EBV-positive NHL. In conjunction with previous reports on sporadic CRCs, this suggests that EBV is not involved in the pathogenesis of CRC.     

Immortalized Epstein-Barr virus-positive B-cell lines obtained by prolonged culture of peripheral blood mononuclear cells from human immunodeficiency virus type 1-positive patients.

OBJECTIVES: To study the factors that determine malignant B cell growth in human immunodeficiency virus type 1 (HIV-1)-infected patients. STUDY DESIGN: B-cell lines (lymphocyte cell lines [LCL]) were developed after nonstimulated culture of peripheral blood mononuclear cells (PBMC) from HIV-1-positive (HIV-1(+)) patients. Human immunodeficiency virus type 1 replication in culture, Epstein-Barr virus (EBV) latent oncogene expression, and cell-to-cell interaction were studied after nonstimulated culture of HIV-1(+) PBMC, analyzing their contribution to LCL appearance. METHODS: Nonstimulated PBMC cultures of HIV-1(+) PBMC and controls (N-PBMC) were established. Lymphocyte cell lines were characterized. Epstein-Barr virus latent membrane protein 1 (LMP-1) and Epstein-Barr nuclear antigen 2 were detected by polymerase chain reaction (PCR). Clonality of LCL was determined by light chain restriction (flow cytometry) and immunoglobulin H chain rearrangement (semi-nested PCR). Peripheral blood mononuclear cell phenotypes were studied at different intervals of culture. RESULTS: Lymphocyte cell lines were obtained in 73% of HIV-1(+) PBMC cultures, compared with 6% in N-PBMC. All LCL were EBV-positive (EBV(+)). B-cell lineage was established, and up to 12 different B-cell clones were expanded from the same individual. Occurrence of LCL was more frequent in cultures with HIV-1 replication, high LMP-1 expression in viable B cells, and high CD4:CD8 ratio. Human immunodeficiency virus type 1 replication persisted in 53% of the LCL. CONCLUSIONS: In vitro HIV-1 replication and persistence of viable EBV(+) lymphoblasts favor spontaneous in vitro outgrowth of LCL in HIV-1(+) patients.