Frequent c-myc oncogene activation and infrequent presence of Epstein- Barr virus genome in AIDS-associated lymphoma

Sixteen cases of histologic intermediate-grade and high-grade AIDS- associated non-Hodgkin's lymphoma (NHL) were studied for the presence and patterns of c-myc gene and bcl-2 locus rearrangements. The presence of Epstein-Barr virus (EBV) sequences and proteins and HTLV-I sequences were also investigated. c-myc gene rearrangements analogous to those observed in sporadic Burkitt lymphomas were detected in 12 of 16 cases. Six of 16 cases had detectable EBV sequences and proteins. None of the cases displayed bcl-2 rearrangements or contained HTLV-I sequences. These data suggest a frequent role for c-myc activation in the pathogenesis of AIDS-associated NHL, independent of histologic type. Conversely, EBV does not appear to be directly involved in lymphomagenesis in the majority of AIDS-associated NHLs.     

Epstein-Barr virus study in malignant lymphoma in Sjögren's syndrome

The association of Epstein-Barr virus (EBV) with Sj?gren's syndrome (SS) is controversial. Reports suggest there is an increased risk of developing lymphoid malignancy in SS. Among our 425 cases of SS, 17 cases of malignant lymphoma (4%), 16 cases of non-Hodgkin's lymphoma (NHL), and 1 case of Hodgkin's disease were found. We looked for an association between EBV and 14 cases of NHL, 13 cases of B-cell lymphoma, and 1 case of T-cell lymphoma in which tissue specimens were available. Epstein-Barr virus-encoded RNA in situ hybridization study and polymerase chain reaction (PCR) study using primers to detect the Bam HI W fragment of EBV with DNA extracts were positive in 2 NHLs: 1 diffuse, large B-cell-type lymphoma, 1 out of 13 cases (8%) of B-cell lymphoma, and 1 angioimmunoblastic T-cell lymphoma with dysproteinemia. In the Bam HI W PCR study of DNA obtained from the labial small salivary glands of 55 cases with SS, 3 cases (5%) were positive. These 3 cases were not associated with malignant lymphoma. Our study revealed that EBV association in SS did not lead to an increased occurrence.     

Lymphoma genesis in the context of HIV infection

The incidence of lymphomas is high among HIV infected patients. These lymphomas are non-Hodgkin's lymphoma (NHL) in 70% of cases and Hodgkin's disease (HD) in 30% of cases. Their localization is often extra-nodal with early dissemination. B-cell high grade NHL predominates. The most frequent histological types are diffuse large B-cell lymphoma (30 to 40%) and Burkitt's lymphoma (40 to 50%). Other histological types are low-grade B-cell lymphoma, polymorphic B cell lymphoma and primary effusion lymphoma. Three main factors are predominant in HIV-related lymphomagenesis: cellular immunodeficiency, oncogene viruses (Epstein-Barr and HHV8) and molecular lesions. HIV-related cellular immunodeficiency leads to the increase of EBV infected B-cells and to the diminution of antitumor immunity. Clonal EBV genome is found in lymphoma cells in 30 to 70% of cases of HIV-related NHL. It expresses oncogenic proteins including LMP-1 which behaves like an activated CD40. It induces the expression of intra-cellular genes which stimulate cell growth and inhibit apoptosis. Cytogenetic and molecular lesions are not specific to HIV-related NHL or to histological subtypes. A better knowledge of these mechanisms should lead to the development of specific targeted treatments (antiviral, cytotoxic anti-EBV lymphocytes, cell cycle regulators).     

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.     

Risk factors for early-onset and late-onset post-transplant lymphoproliferative disorder in kidney recipients in the United States

Solid-organ transplant recipients have an elevated risk for some malignancies because of the requirement for immunosuppression [1]. In particular, non-Hodgkin's lymphoma (NHL) is common and comprises one end of a spectrum of post-transplant lymphoproliferative disorder (PTLD) ranging from benign hyperplasia to lymphoid malignancy [2]. PTLD risk is influenced by the type of organ transplanted, the age and Epstein-Barr virus (EBV) serostatus of the transplant recipient, and the intensity of immunosuppression [3-9]. PTLD incidence is high immediately after transplantation, decreases subsequently, and then rises again 4-5 years from transplantation [10,11]. This incidence pattern suggests the presence of separate early-onset and late-onset PTLD subtypes. Early-onset PTLDs tend to be EBV-positive and, when extranodal, are more likely than late-onset PTLDs to be localized to the transplanted organ [12,13]. Late-onset PTLD is less likely to be associated with EBV and, overall, is more likely than early-onset PTLD to be extranodal [13,14]. The Scientific Registry of Transplant Recipients (SRTR) includes data on a large number of solid-organ transplant recipients in the United States and information on malignancies diagnosed post-transplantation. We used these data to conduct a retrospective cohort study among kidney transplant recipients to examine differences in risk factors between early-onset PTLD and late-onset PTLD.     

Recurrent B-cell non-Hodgkin's lymphoma in two brothers with X-linked lymphoproliferative disease without evidence for Epstein-Barr virus infection

We present two male siblings suffering from recurrent manifestations of B-cell non-Hodgkin's lymphoma (NHL) and recurrent infections of the lower respiratory tract associated with bronchiectasis. Immunodeficiency could not be demonstrated by any laboratory investigation. In both patients, lymphomas developed without evidence for Epstein-Barr virus (EBV) infection, i.e. no antibody response to EBV-specific antigens, negative EBV-PCR (polymerase chain reaction) in peripheral blood cells, and absence of latent membrane protein (LMP) and EBV-encoded RNA (EBER) in lymphoma cells. Molecular analysis of the SH2D1A, the gene for X-linked lymphoproliferative disease (XLP) led to the identification of a deletion in the first exon in both patients. Therefore, we postulate that the genetic defect and the following dysregulation of the B-/T-cell interaction rendered these patients susceptible to the early onset of B-cell NHL and that EBV infection is not an obligate prerequisite.     

The bcl-2 oncogene in Hodgkin's disease arising in the setting of follicular non-Hodgkin's lymphoma

Expression of the bcl-2 proto-oncogene on chromosome 18 is deregulated by the 14; 18 chromosomal translocation, an abnormality that is consistently associated with follicular non-Hodgkin's lymphomas (NHL). Because bcl-2 is believed to function by prolonging cell survival rather than by increasing proliferation, the presence of t(14; 18) in Hodgkin's disease (HD) would have profound implications for the pathogenesis of this neoplasm. We evaluated 32 cases of HD for t(14; 18) by polymerase chain reaction (PCR). These results were correlated with expression of bcl-2 oncogenic protein by Hodgkin cells and with the presence of Epstein-Barr virus (EBV), as determined by immunohistochemistry or in situ hybridization. PCR provided evidence of t(14; 18) in only 2 HD cases (6%), both of which were associated with a prior history of follicular lymphoma, and both of which were among the 7 cases (22%) with strong bcl-2 expression in Hodgkin cells. In at least 1 of the cases, the translocation involved identical chromosomal breakpoints in both types of lymphoma. Furthermore, 7 additional cases of combined follicular NHL and HD showed strong bcl-2 staining in Hodgkin cells. Although EBV was detected in 6 of 30 cases, it was not associated with t(14; 18) and usually not with strong bcl-2 expression. These results suggest that a small proportion of HD cases might evolve from follicular NHL, possibly through molecular events superimposed on the t(14; 18). High-level bcl-2 expression in Hodgkin cells is a potentially useful but not definitive marker for these cases.     

Characterization of posttransplant lymphomas that express T-cell- associated markers: immunophenotypes, molecular genetics, cytogenetics, and heterotransplantation in severe combined immunodeficient mice

Immunosuppressed individuals are at high risk for the development of hematologic malignancies. The typical lymphomas arising in organ transplant recipients are B-cell non-Hodgkin's lymphomas that contain Epstein-Barr virus (EBV) DNA sequences. We investigated the characteristics of posttransplant lymphomas that lacked expression of the usual markers associated with EBV transformation. We describe four large-cell lymphomas seen recently at our institution. Two of these four cases were CD4+, one was CD8+, and in one staining for CD4 and CD8 expression was not performed. One CD4+ lymphoma was a CD30+, EBV- large- cell lymphoma from a 65-year-old kidney transplant recipient, the second was an EBV+ large-cell lymphoma from a 25-year-old heart transplant patient. Two T-cell lymphomas were EBV+ and had clonal T- cell receptor beta gene rearrangements. The other two lymphomas expressed T-cell markers CD4 and CD43, and lacked expression of B-cell markers CD19, CD20, CD21, CD22, CD23, and surface Ig. Both CD4+ lymphomas were tumorigenic after their heterotransplantation into severe combined immunodeficient (SCID) mice. Cytogenetics, immunophenotyping, and genotyping of the secondary tumors from SCID mice showed their clonality and identity with the patients' primary tumors. Novel CD4+ lymphoma cell lines, LH521/4 and LK418/4, were established from tumors that had been passaged in SCID mice. An immunodeficient environment may facilitate the growth of these T-cell or biphenotypic lymphomas; the etiology of their genesis can include transformation with EBV and other, as yet unidentified mechanisms.     

EBER-1 positive diffuse large cell lymphoma presenting as lupus nephritis

Approximately one-third of membranous glomerulonephritis (MGN) cases in adults are associated with systemic diseases, including systemic lupus erythematosus (SLE) or malignancies. Malignancy-associated glomerulonephritis is rarely found in non-Hodgkin's lymphoma (NHL). Epstein-Barr virus (EBV) has been postulated to contribute to the pathogenesis of both SLE and NHL. We described a 37-year-old woman with nephrotic syndrome who presented with clinical features of SLE and renal-biopsy revealed lupus MGN. The patient also suffered from concomitant progressive lymphadenopathy and NHL (diffuse large B-cell type) was demonstrated by neck lymph node biopsy. Serologic studies demonstrated EBV infection and specific EBV antigens were present on lymph node and metastatic sites. We offer a discussion regarding the complex relationships between SLE, NHL, MGN and EBV.     

Primary gastric non-Hodgkin's lymphoma: a clinicopathological study of 41 patients

Pathological findings in 41 patients (male/female ratio: 1.3/1) with primary localized gastric non-Hodgkin's lymphoma (NHL) were retrospectively studied and correlated with survival. The median observation period after diagnosis was 32 (0–189) months. Nineteen patients were low-grade NHL, all but one B-cell lymphomas of the mucosa-associated lymphoid tissue (MALT) type. Twenty-two patients had primary (n-7) or secondary (n=15) high-grade lymphomas; Musshoff stage IE was found in 29 and II E in 12 cases. The median age at diagnosis was 61 years (range, 26–88 years), and proliferation, measured by the number of mitosis and Ki-67 antigen positivity (MIB-1), was high or moderately high in 24 cases and low in 17 cases. Follicular lymphatic hyperplasia could be found in 25 of 34 evaluable cases, more often in low-grade than in high-grade NHL. Most of the patients were treated by resective surgery and additional ratio- or chemotherapy. Thirteen patients (31%) died (median survival: 10 months), 5 of them within 3 months after surgery owing to postoperative complications. Survival was superior, though not statistically significant, in low-grade lymphomas. Our retrospective anlysis of heterogeneously treated gastric lymphomas reveals that gastric lymphomas, especially of the low-grade MALT type, often remain a localized disease with a good long-term prognosis. Our study confirms previous reports indicating that lymphomas of the MALT type represent a specific clinicopathological entity.     

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.     

Direct Epstein-Barr virus (EBV) typing on peripheral blood mononuclear cells: no association between EBV type 2 infection or superinfection and the development of acquired immunodeficiency syndrome-related non-Hodgkin's lymphoma.

In the literature, a correlation has been suggested between the occurrence of acquired immunodeficiency syndrome (AIDS)-related non-Hodgkin's lymphomas (NHL) and Epstein-Barr virus (EBV) type 2 infection. To further investigate a possible role for EBV type 2 infection in the development of AIDS-NHL, we developed a sensitive and type-specific nested polymerase chain reaction (PCR) assay and analyzed EBV types directly on peripheral blood mononuclear cells (PBMC) in three subgroups of human immunodeficiency virus (HIV)-1 infected individuals: 30 AIDS-NHL patients, 42 individuals progressing to AIDS without lymphoma (PROG), either developing opportunistic infections (AIDS-OI) or Kaposi's sarcoma (AIDS-KS), and 18 long-term asymptomatic individuals (LTA). Furthermore, EBV type analysis was performed on PBMC samples obtained from AIDS-NHL patients in the course of HIV-1 infection. The results showed that: (1) direct analysis of PBMC is superior to analysis of B-lymphoblastoid cell lines (B-LCL) grown from the same PBMC samples; (2) in HIV-1 infected individuals, there is a high prevalence of EBV type 2 infection (50% in LTA, 62% in progressors, and 53% in AIDS-NHL) and superinfection with both type 1 and 2 (24% in LTA, 40% in progressors, and 47% in AIDS-NHL); (3) EBV type 2 (super)infection is not associated with an increased risk for development of AIDS-NHL; (4) type 2 infection can be found early in HIV-1 infection, and neither type 2 infection nor superinfection correlates with a failing immune system.     

Epstein-Barr virus clonality in lymphomas occurring in patients with rheumatoid arthritis

Objective. A causative role for Epstein-Barr virus (EBV) in the development of lymphoma in patients with rheumatoid arthritis (RA) has been proposed. We investigated the molecular features of EBV-positive diffuse large cell lymphomas in 2 patients with RA. Methods. Southern blot analysis for immunoglobulin gene rearrangements, terminal repeat analysis for clonality of the EBV genome, and double-labeling of the lymphoma cells by in situ hybridization and immuno-peroxidase staining were performed. Results. In both cases, double-labeling studies localized the EBV genome to the malignant B cells. Both neoplasms contained clonal immunoglobulin gene rearrangements and clonal EBV genomes. Conclusion. Our data indicate that EBV infection was an early step in the development of these neoplasms. The findings further extend knowledge on the similarity of this subset of lymphomas to posttransplantation lymphomas and emphasize the role of immunosuppression in their genesis.     

Frequent occurrence of B-cell lymphomas in angioimmunoblastic T-cell lymphoma and proliferation of Epstein-Barr virus-infected cells in early cases

Secondary lymphomas occurring in the setting of angioimmunoblastic T-cell lymphoma (AILT) are considered to be rare. Their occurrence has been attributed to Epstein-Barr virus (EBV)-associated lymphoproliferations. A previous study detected a dysregulated hypermutation process in B-cells of AILT. The present study aimed at estimating the frequency of B-cell lymphomas in AILT. By studying the expression of EBV and activation-induced cytidine deaminase (AID) as an indicator of hypermutating cells, we assessed whether B-cell lymphoproliferations in AILT were strictly associated with EBV and whether hypermutation might contribute to lymphomagenesis. Among 161 cases of AILT, diagnosed between 1996 and 2005 at the lymph node registry, Frankfurt, Germany, 19 cases were detected that also had B-cell non-Hodgkin lymphoma (NHL) and two cases had classical Hodgkin lymphoma (HL). EBV was detected in tumour cells of 7/18 NHL and both HL, suggesting that factors other than EBV contribute to lymphomagenesis. AID was expressed in AILT in large cells disseminated in the tissue, implying that the process of somatic hypermutation is ongoing in AILT, although the GC architecture is disrupted. This might be relevant in the development of secondary lymphomas.     

Association of the subtype 2 of the Epstein-Barr virus with T-cell non- Hodgkin's lymphoma of the midline granuloma type [see comments]

Lethal midline granuloma (LMG) is associated with Epstein-Barr virus (EBV). The latter has at least two subtypes with different biological properties. The subtypes can be identified by their genomic configuration. Using EBV-RNA (EBER) in situ hybridization and EBV polymerase chain reaction (PCR), we have looked for the presence of EBV in six LMGs and six non-Hodgkin's lymphomas (NHLs) located in the nasopharyngeal region, and determined the subtype of EBV. Six of six LMGs were positive by PCR and EBER in situ hybridization, whereas NHLs were either negative or, in three of six cases, showed few EBER- positive cells considered to be nonneoplastic lymphocytes. The subtype 2 was found in LMG lesions of three of six patients; the remaining three of six patients with LMG had the generally occurring subtype 1. The results indicate that the association of EBV with NHL may depend more on tumor type than on its localization. The occurrence of the rare subtype 2 in LMG may relate to a covert immune defect.     

A possible role for Epstein-Barr virus in tumorigenesis after immunosuppression in cases of renal transplantation

Eight secondary malignancies developing after renal transplantation were investigated in terms of a possible role of the Epstein-Barr virus (EBV). In five cases, four gastric cancers and one colonic cancer, the presence of EBV was proven by the polymerase chain reaction (PCR), all four gastric lesions being confirmed to have a massive EBV infection by in situ hydridization. Two cases demonstrated monoclonal infection with EBV, as indicated by a single band of the lymphocyte-defined membrane antigen tandem-repeat gene using PCR, and were immunohistochemically positive for the latente membrane protein 1. Our series suggests that gastrointestinal cancer predominates as a secondary malignancy in states of induced severe immunosuppression, and that EBV may play an important role in tumorigenesis as an oncovirus.Abbreviations PCR polymerase chain reaction - ISH in situ hybridization - EBV Epstein-Barr virus - IR internal repeat - LYOMA lymphocyte-determined membrane antigen     

Epstein-barr virus-associated malignancies: epidemiologic patterns and etiologic implications

Epstein-Barr virus (EBV), a ubiquitous B-lymphotrophic herpesvirus, has been found in the tumor cells of a heterogeneous group of malignancies (Burkitt's lymphoma, lymphomas associated with immunosuppression, other non-Hodgkin's lymphomas, Hodgkin's disease, nasopharyngeal carcinoma, gastric adenocarcinoma, lymphoepithelioma-like carcinomas, and immunodeficiency-related leiomyosarcoma). As the epidemiologic characteristics of these cancers have not been considered together, this review seeks to relate their incidence patterns and risk factors to EBV biology and virus-host interaction in an attempt to help elucidate factors involved in EBV-related carcinogenesis. We include a brief review of EBV virology and primary infection to provide a biologic context for considering the epidemiology, summarize the most salient epidemiologic features of each malignancy, synthesize epidemiologic data by risk factor to uncover commonalities and informative contrasts across the diseases, and propose hypotheses regarding etiologic mechanisms, based on the possible effect of the risk factors at various stages in the viral life cycle.     

Soluble CD23 in cerebrospinal fluid: a marker of AIDS-related non-Hodgkin's lymphoma in the brain.

BACKGROUND: AIDS-related non-Hodgkin's lymphoma (NHL) includes systemic lymphomas, often with brain involvement, and primary central nervous system (CNS) lymphomas. OBJECTIVE: To examine if measurement of soluble CD23 (sCD23) in cerebrospinal fluid (CSF) is useful in the diagnosis and follow-up of AIDS-related NHL. METHOD: sCD23 was measured by enzyme-linked immunosorbent assay and EBV DNA by nested polymerase chain reaction for a group of 134 patients. The NHL group included 14 patients with primary HIV-1 CNS lymphoma, 12 patients with brain involvement of systemic HIV-1 NHL and 10 patients with systemic HIV-1 NHL without brain involvement. These were compared with HIV-1-infected patients with cerebral toxoplasmosis (19), progressive multifocal leukoencephalitis (PML; 8) and AIDS-related dementia (17) and with asymptomatic HIV-1 carriers (54) and uninfected individuals (50). The levels of sCD23 were compared with the presence of Epstein-Barr virus (EBV) DNA in CSF. RESULTS: Significantly higher levels of sCD23 were found in the CSF of the patients with brain lymphoma than in those with systemic NHL (P < 0.002) or with cerebral toxoplasmosis, PML and AIDS-related dementia (P < 0.0001). The sensitivity and specificity of sCD23 in CSF as a marker for detection of brain NHL were 77% and 94%, respectively. High levels of sCD23 were found in CSF from patients with brain NHL independently of the presence (18 out of 26) or absence (8 out of 26) of EBV DNA. CONCLUSIONS: The sCD23 in CSF of HIV-1-infected patients may represent an additional, non-invasive marker for diagnosis of brain involvement in AIDS-related NHL.     

Infection-associated lymphomas derived from marginal zone B cells: a model of antigen-driven lymphoproliferation

Non-Hodgkin lymphomas develop from nodal and extranodal lymphoid tissues. A distinct subset of extranodal lymphomas arising from B cells of the marginal zone (MZ) of mucosa-associated lymphoid tissue (MALT) or spleen has been individualized. Growing evidence indicates that MZ lymphomas are associated with chronic antigenic stimulation by microbial pathogens and/or autoantigens. The list of microbial species associated with MZ lymphoproliferations has grown longer with molecular investigations and now comprises at least 5 distinct members: H. pylori, C. jejuni, B. burgdorferi, C. psittaci, and hepatitis C virus (HCV), which have been associated with gastric lymphoma, immunoproliferative small intestinal disease, cutaneous lymphoma, ocular lymphoma, and spleen lymphoma, respectively. A pathophysiologic scenario involving chronic and sustained stimulation of the immune system leading to lymphoid transformation has emerged. It defines a distinct category of infection-associated lymphoid malignancies, in which the infectious agent does not directly infect and transform lymphoid cells, as do the lymphotropic oncogenic viruses Epstein-Barr virus (EBV), human herpesvirus 8 (HHV8), and human T-lymphotropic virus 1 (HTLV-1), but rather indirectly increases the probability of lymphoid transformation by chronically stimulating the immune system to maintain a protracted proliferative state.     

Subtypes of Epstein-Barr virus in human immunodeficiency virus-associated non-Hodgkin lymphoma.

Biopsy samples obtained from 20 patients with human immunodeficiency virus (HIV)-associated non-Hodgkin lymphoma (NHL) were assessed for evidence of Epstein-Barr virus (EBV) and HIV sequences. DNA was extracted from formalin-fixed, paraffin-embedded NHL tissue and specific viral gene sequences were sought using the polymerase chain reaction (PCR). EBV sequences were found in 10 NHL samples (50%), with five tumors showing A-type and five B-type sequences. By serologic testing, 18 of 19 patients had antibodies to EBV, with 14 patients having antibodies to A-type EBV and 11 to B-type EBV. Serology confirmed the high prevalence of type B EBV in HIV-infected patients, but was not a reliable indicator of the EBV subtype present in the lymphomas. HIV sequences were present in biopsy tissue but at a level consistent with an origin from bystander HIV-infected cells. All 20 patients were negative by enzyme-linked immunosorbent assay for antibodies to human T-cell leukemia virus-type I. The high prevalence of type B EBV in these tumors is similar to the findings in endemic Burkitt's lymphoma, where 40% of the tumors have type B viral sequences. In normal populations, type B EBV is rarely found outside the nasopharynx. These studies support the hypothesis that EBV is an important cofactor in NHL in HIV-infected persons. The finding that B-type EBV is present in 25% of HIV-associated NHL suggests that this EBV subtype may be an important human pathogen with a wider geographic distribution than originally thought.