High levels of CD8-positive lymphocytes expressing CD45R0, granzyme B, and Ki-67 in lymph nodes of HIV-infected individuals are not associated with increased mortality.

Lymph nodes constitute the major site of HIV replication and of immunological response to HIV. To study the role of cytotoxic and mitotic active CD8(+) lymphocytes in lymph nodes during HIV infection we examined 28 formalin-fixed, paraffin-embedded lymph nodes sampled from 1984 to 1986 from 21 HIV-seropositive patients and seven HIV-negative patients. Eleven of the HIV-positive patients died within 78 months of biopsy time and 10 patients were alive on July 1, 1998. Double immunohistochemical staining procedures were developed to identify CD8(+) cells expressing CD45R0, granzyme B, and Ki-67. A stereological method was used to count the different cell types in the lymph nodes. There were no significant differences in the total cell (nucleated) and CD3(+) cell concentrations between the three groups. However, there were significantly higher concentrations of CD3(+)CD8(+), CD8(+)CD45R0(+), and CD8(+)Ki-67(+) lymphocytes in the HIV patients compared with the control group. Furthermore, there was a tendency for the HIV-deceased group to have lower levels of CD8(+)granzyme B(+) and CD8(+)Ki-67(+) lymphocyte concentrations compared with the HIV-alive group. Three HIV patients, who progressed to death within 49 months of biopsy time, were among the patients with the lowest concentrations of CD8(+)granzyme B(+) and CD8(+)Ki-67(+) lymphocytes. This finding allowed us to conclude that CD8(+) lymphocytes expressing high levels of CD45R0, granzyme B, and Ki-67 in lymph nodes of HIV patients are not related to increased mortality, whereas low concentrations of CD8(+) granzyme B(+) and CD8(+)Ki-67(+) lymphocytes may be associated with poor prognosis.

Improved prognosis of Epstein-Barr virus associated childhood Hodgkin's lymphoma: study of 47 South African cases.

AIM: To study the distribution of Hodgkin's lymphoma in South African children and report the incidence of Epstein-Barr virus (EBV) as regards age, race, sex, and histological subtype; to investigate whether EBV is relevant to survival. METHODS: Immunohistochemistry (IHC) and in situ hybridisation (ISH) to detect EBV were performed on 47 South African children with classical Hodgkin's lymphoma, ranging in age from 3 to 14 years and coming from different ethnic backgrounds. The correlation between the presence of the virus and clinical outcome was assessed. RESULTS: The nodular sclerosing subtype predominated, comprising 89% of cases; the remaining 11% were of the mixed cellularity subtype. EBV was present in 68%. Full clinical data were available for 36 cases; EBV positive patients presented with less aggressive symptoms at diagnosis and had a significantly longer median survival than EBV negative patients. CONCLUSIONS: The distribution of EBV in South African childhood Hodgkin's lymphoma follows a pattern intermediate to that of industrialised and non-industrialized countries. Furthermore, our data suggest that there is an association between poor prognosis and the non-detection of EBV products in South African childhood Hodgkin's lymphoma.

Epstein-Barr virus distribution in Hodgkin's disease in an unselected Swedish population.

All patients with Hodgkin's disease (HD) (n = 117) identified in the Uppsala/Orebro region of Sweden between 1985 and 1988 were examined for the presence of Epstein-Barr virus (EBV) in the Hodgkin and Reed-Sternberg (HRS) cells. EBV was detected with LMP-1 immunostaining and in situ hybridization for EBERs. Overall, 32 (27%) tumours were EBV-positive but there were significant differences in EBV-positivity between histopathological subgroups (p = 0.03). In MC, 8/21 (38%) were positive, in NS 20/67 (23%), LD 3/3, LP 1/5, and in unclassified 0/1. Patients with EBV-positive tumours were significantly older, mean 52 vs. 42 years (p = 0.02), and were likely to have significantly more B-symptoms or advanced stage disease. Patients with EBV-positive tumours tended to have a poorer survival rate (p = 0.11). The proportion of EBV-positive tumours, and especially the proportion of EBV-positive MC, was lower than previously reported. This could be explained by selection of patients from previous studies, or by differences in EBV-positivity in different geographical or ethnic populations of HD.

Lack of correlation between EBV serology and presence of EBV in the Hodgkin and Reed-Sternberg cells of patients with Hodgkin's disease.

Epstein-Barr virus (EBV) is detected in Hodgkin and Reed-Sternberg (HRS) cells in up to 50% of patients with Hodgkin's disease (HD). HD patients have been reported to express high serum titers against EBV antigens, even prior to the diagnosis of HD. Patients with high serum titers have a poorer prognosis. The aim of this study was to examine the relationship between the presence of EBV in HRS cells and the antibody titers reactive with different EBV antigens. Frozen serum and histopathological tissues were available from 107 untreated HD patients diagnosed between 1979 and 1991. The presence of EBV in the HRS cells was evaluated with immunohistochemistry directed against the LMP-1 antigen and/or with in situ hybridization of EBER-1. Analyses were performed of serum titers against early antigen (EA), diffuse (IgA and IgG) and restricted (IgG), virus-capsid antigen (VCA) (IgA and IgG), and EBV-encoded nuclear antigens (EBNA, EBNA 1, EBNA 2A, EBNA 2B, EBNA 6). EBV was detected in 27/107 (25%) tumor specimens, with a higher proportion in the MC group 8/13 (62%) (p < 0.01). IgG VCA and EBNA were detected in 99/107 (93%), evidence of a previous EBV infection. There were no significant relationships between antibody titers reactive with different EBV antigens and detectable EBV in HRS cells. Furthermore, there did not appear to be any relationship between EBV serology or the presence of EBV in HRS cells and clinical outcome. The role of EBV in the development of HD, especially its relationship to the immunological response, remains unclear.

Epstein-Barr virus (EBV) and Hodgkin's disease in a multi-ethnic population in Malaysia.

The Epstein-Barr virus (EBV) has been implicated as a contributing factor in the development of Hodgkin's disease. Western cases of Hodgkin's disease have shown the presence of EBV in Hodgkin and Reed-Sternberg cells in approximately 50%. We studied a total of 100 consecutive cases of Hodgkin's disease from Malaysia, with the aim to elucidate its association with EBV in a multi-ethnic Asian population. Of 34 patients (34%) less than 15 years of age (childhood), 25 had classical Hodgkin's disease (eight nodular sclerosis, 16 mixed cellularity, one lymphocyte depleted) and nine had lymphocyte predominance Hodgkin's disease. Of the 66 from patients aged 15 years and above, 33 had nodular sclerosis, 24 mixed cellularity, two lymphocyte depleted, one unclassifiable and six lymphocyte predominance Hodgkin's disease. The ethnic distribution of classical Hodgkin's disease was: Malay 23, Chinese 32 and Indian 30 (Malay:Chinese:Indian = 1:1.4:1.3), and the ethnic distribution in the 15 cases of lymphocyte predominance Hodgkin's disease was: Malay four, Chinese 10 and Indian one. Taking into account the ethnic distribution of the general population and of hospital admissions, there appears to be a significant predilection of classical Hodgkin's disease cases in ethnic Indian compared to non-Indian patients (chi-squared test, 0.025 > P > 0.01). Eighty-one cases were tested for the presence of EBV by in situ hybridization for EBV encoded RNA, and 57 cases by immunostaining for EBV latent membrane protein 1. In the younger age group, all except one of the 15 cases (nine mixed cellularity, six nodular sclerosis) showed the presence of EBV (93%). In the older age group, EBV was detected (52%) in the following proportion: 6/27 nodular sclerosis, 19/22 mixed cellularity, 1/2 lymphocyte depleted, 1/1 unclassifiable. None of the 14 cases of lymphocyte predominance Hodgkin's disease showed the presence of EBV in the Hodgkin and Reed-Sternberg cells. The findings suggest a strong association of EBV with Hodgkin's disease in Malaysians (41/67, 61%), in particular childhood cases (93%). In adults, the association with EBV is significantly higher in the mixed cellularity subtype (86%) compared with the nodular sclerosis subtype (22%).

Epstein-Barr virus-associated Hodgkin's disease: epidemiologic characteristics in international data.

Hodgkin's disease (HD) has long been suspected to have an infectious precursor, and indirect evidence has implicated Epstein-Barr virus (EBV), a ubiquitous herpesvirus, as a causal agent. Recent molecular studies using EBER in situ hybridization or latency membrane protein-I (LMP-I) immunohistochemistry have identified EBV latent infection in up to 50% of HD tumors. However, the epidemiologic features of these cases have not been examined in detail. To explore the epidemiology of EBV-positive HD so as to understand the role of EBV in HD etiology more clearly, this project accumulated patient data from 14 studies that had applied these EBV assays to HD tumors. With information on age at diagnosis, sex, ethnicity, histologic subtype, country of residence, clinical stage and EBV tumor status from 1,546 HD patients, we examined risk for EBV-positive disease using logistic regression. Forty percent of subjects had EBV-positive tumors, and EBV prevalence varied significantly across groups defined by the study variables. Odds ratios (OR) for EBV-associated HD were significantly elevated for Hispanics vs. whites (OR = 4.1), mixed cellularity vs. nodular sclerosis histologic subtypes (OR = 7.3, 13.4, 4.9 for ages 0-14, 15-49, 50+ years), children from economically less-developed vs. more-developed regions and young adult males vs. females (OR = 2.5). These findings suggest that age, sex, ethnicity and the physiologic effects of poverty may represent biologic modifiers of the EBV association and confirm that this association is strongly but variably linked to histologic subtype. The data augment biologic evidence that EBV is actively involved in HD pathogenesis in some cases but describe epidemiologic complexity in this process.

An immunohistochemical study of TAL-1 protein expression in leukaemias and lymphomas with a novel monoclonal antibody, 2TL 242.

Fifty formalin fixed, paraffin-embedded cases of T-acute lymphoblastic leukaemia (T-ALL) from 12 bone marrow trephines and 38 lymph nodes were stained with a new monoclonal antibody, 2TL 242, raised against recombinant TAL1 protein. The antibody recognizes TAL-1 polypeptides of molecular weight 39 and 41 kD (full length). In addition, a variety of other leukaemias and lymphomas were also stained with 2TL 242. Twenty-four of the 50 cases of T-ALL showed nuclear positivity, ranging from 10 to 90 per cent of leukaemic cells. A positive staining reaction was nuclear and stippled in pattern. Nuclear staining was not seen in any other type of leukaemia or lymphoma. Five cases of follicular lymphoma showed diffuse cytoplasmic staining of variable intensity. Although some background staining is obtained with this antibody, positive nuclear staining is easily distinguishable. This monoclonal antibody has a potential role in primary diagnosis and in the detection of minimal residual disease in T-ALL.

SCL/Tal-1 expression in T-acute lymphoblastic leukemia: an immunohistochemical and genotypic study.

A comparative study of the immunohistochemical (Stem cell leukemia/T-cell acute leukemia [SCL/TAL-1] protein expression) and genotypic (deletions in the SCL/tal-1 gene) findings in T-acute lymphoblastic leukemia (T-ALL) is presented. Formalin-fixed tissue from 50 cases of T-ALL were stained with a novel monoclonal antibody, 2TL 242, which recognizes SCL/TAL-1 protein. Twenty-four cases showed nuclear immunolabeling of leukemic cells. Nuclear positivity was not evident in any other type of leukemia or lymphoma tested with the antibody. Genotypic analysis of 25 cases of T-ALL showed a deletion involving the SCL/tal-1 gene in nine cases. These results suggest that protein expression is not dependent on derangement of the SCL/tal-1 gene, because immunohistochemical detection of the protein was noted in the presence and absence of a tal-d1 deletion.

Epstein-Barr virus (EBV) in Malaysian upper-aerodigestive-tract lymphoma: incidence and sub-type.

Epstein-Barr virus (EBV) type B, a less potent transformer of B lymphocytes than type A, has rarely been detected in EBV-associated neoplasms except in AIDS-related lymphomas, in which about 50% of the cases contained this sub-type. In this study we analyzed the association of EBV and the distribution of virus sub-types in Asian non-Hodgkin's lymphoma (NHL) of the upper aerodigestive tract. We studied archival material of 29 NHL cases from Malaysia. B- and T-cell associated antigens were demonstrated by immunohistochemistry, and EBV early RNA EBER-1 was demonstrated using the RNA in situ hybridization technique. EBV was detected in the majority of tumour cells in 11/13 T-NHL but in only 1/16 B-NHL. EBV was sub-typed by single-step polymerase chain reaction of the EBNA-2 gene. This was successful in 9/10 cases of EBER-1-positive tumours and all contained type-A virus only. Our results showed a preponderance of T-cell lymphoma of the upper aerodigestive tract in the ethnic Chinese group of Malaysian patients, and EBV was strongly associated with T-NHL but not with B-NHL. Our results suggest that type-A EBV is the prevalent sub-type in Asian NHL of the upper aerodigestive tract, similarly to findings in Asian nasopharyngeal carcinoma.

Identification of potential hot spots in the carboxy-terminal part of the Epstein-Barr virus (EBV) BNLF-1 gene in both malignant and benign EBV-associated diseases: high frequency of a 30-bp deletion in Malaysian and Danish peripheral T-cell lymphomas.

In this study, we have sequenced the C-terminal part of the Epstein-Barr virus (EBV)-BNLF-1 gene encoding for the latent membrane protein-1 from tissues of EBV-positive Danish Hodgkin's disease (HD) and of Danish and Malaysian peripheral T-cell lymphomas (PTLs) and from tonsils of Danish infectious mononucleosis (IM). Our study showed that some of the 7 single-base mutations and the 30-bp deletion previously detected between codons of amino acid 322 and 366 in the BNLF-1 gene of the nasopharyngeal carcinoma cell line CAO were present in all Malaysian PTLs and in 60% of the Danish PTLs. In HD and the IM cases, the mutations were present in about 30%. The 30-bp deletion and the single base mutations occurred independently, and mutations were detectable in the majority of EBV type B-positive cases. These findings suggest that the 30-bp deletion and the 7 single-base mutations in the C-terminal part of the CAO-BNLF-1 gene do not characterize a new EBV type A substrain. Rather, some of the positions of single base mutations and the 30-bp deletion are hot spots that may have mutated independently through the evolution of EBV strains.

Expression of human recombination activating genes (RAG-1 and RAG-2) in lymphoma.

Two recently discovered genes, the recombination activating genes 1 and 2 (RAG-1 and RAG-2), are necessary to perform variable (V), diversity (D), and joining (J) recombination. They synergistically activate VDJ recombination to generate immunocompetent lymphocytes. Disruption of either gene results in a maturation arrest at a very early B and T cell progenitor stage. Expression and downregulation of RAG's are closely associated with interleukin 7, sIgM and TCR-CD3 complex, respectively. Assessment of RAG mRNA expression is a valuable marker in identifying the genotypic maturation status of leukemias and lymphomas. Persistent RAG expression in otherwise mature lymphoid proliferations may explain puzzling biological and clinical observations such as multiple rearrangements in lymphomas with a mature phenotype. Lack of RAG expression in Hodgkin's disease with abundant Reed-Sternberg cells is consistent with a mature phenotype of the latter. Availability of a anti-RAG-1 monoclonal antibody in the near future will facilitate RAG analysis of lymphomas.

Evaluation of Epstein-Barr virus antibody patterns and detection of viral markers in the biopsies of patients with Hodgkin's disease.

We assessed the relationship of Epstein-Barr virus (EBV) serology to the presence or absence of EBV genome in 39 cases of Hodgkin's disease (HD). Biopsies from patients included in 2 previous published studies, 1 involving patients from the United States (eastern Massachusetts) and 1 from Denmark, were evaluated for EBV (EBER-1) and latent membrane protein (LMP-1). The presence of EBV in Reed-Sternberg cells in the biopsies correlated with the histologic subtype of HD (mixed cellularity and lymphocyte depletion) but not with IgG antibody titers against the viral capsid antigen (VCA). These data suggest that, unlike Burkitt's lymphoma, the IgG antibody against VCA is not predictive of the presence or absence of EBV in Reed-Sternberg cells in HD. The predictive value of other antibodies should be evaluated.

Detection of Epstein-Barr virus small RNAs in routine paraffin sections using non-isotopic RNA/RNA in situ hybridization.

The Epstein-Barr virus (EBV) is associated with an increasing range of reactive and neoplastic lesions. There is a need for a sensitive and specific method for detecting latent EBV in routine histological sections. We report the use of a highly sensitive paraffin section RNA/RNA in situ hybridization (ISH) technique using digoxigenin-labelled antisense riboprobes for demonstrating EBV encoded small RNAs (EBERs), EBV gene products that are transcribed in abundance during latent EBV infection. We applied EBER-ISH to 846 paraffin embedded specimens, including cases of reactive lymphoid hyperplasia (n = 28), infectious mononucleosis (16), Burkitt's lymphoma (44), immunodeficiency-associated lymphomas in transplant recipients (9) and AIDS patients (128), Hodgkin's disease (130), CD30 antigen positive lymphomas (106), peripheral T-cell lymphomas (104), sporadic B-cell non-Hodgkin's lymphomas (162), undifferentiated nasopharyngeal carcinoma (86), salivary gland lymphoepithelioma (11), and oral hairy leukoplakia (5). Strong, reproducible EBER staining was seen in EBV latently infected cells in archival surgical biopsy and autopsy specimens. EBER-ISH is specific, has a sensitivity comparable to that of the polymerase chain reaction, and is now the method of choice for the in situ detection of latent EBV infection.

Involvement of aberrant p53 expression and human papillomavirus in carcinoma of the head, neck and esophagus.

Biopsies from 34 patients with cancer of the head, neck or esophagus, 2 laryngeal papillomas, and 2 normal tonsils were analysed for human papillomavirus (HPV), Epstein Barr virus (EBV) genomes and mutated or elevated levels of p53. In 4 biopsies p53 was also analysed by DNA sequencing. HPV type 31 was found in one laryngeal cancer with normal p53 and HPV type 16 in two tonsil cancers with aberrant p53 expression. EBV was detected by PCR in 11 biopsies, but in situ hybridisation and immunohistochemistry, did not confirm this finding. Aberrant p53 expression was observed in approximately half of the tumours. These results support the involvement of both aberrant p53 expression and HPV in the aetiology of squamous cell carcinoma of the head and neck.

High frequency of Epstein-Barr virus in Chinese peripheral T-cell lymphoma.

Forty-two cases of Chinese T-cell lymphoma were studied for expression of Epstein-Barr virus (EBV) encoded RNA (EBER-1) and EBV latent membrane protein-1 (LMP-1) using in situ hybridization and immunohistochemistry, respectively. EBV was detected in tumour cells in 24/39 peripheral T-cell lymphomas (62%), comprising 18/27 pleomorphic, medium and large cell lymphomas (67%), 4/6 angioimmunoblastic lymphadenopathy-like lymphomas (67%), 2/2 Lennert's lymphomas, 0/2 anaplastic large cell lymphomas, and 0/2 T-zone lymphomas. EBV was not found in three T-lymphoblastic lymphomas. EBV was associated with 12/24 nodal (50%) compared with 12/15 extranodal (80%) peripheral T-cell lymphomas. In EBV positive nodal lymphomas, 9/12 cases (75%) contained less than 10% EBER positive tumour cells. In EBV positive extranodal lymphomas, 9/11 cases (82%) showed EBV gene expression in more than 50% of the tumour cells, and in five of these almost all tumour cells were positive. Lymphomas of the nasopharynx (mainly midline granuloma-type) showed EBER-1 expression in nearly all tumour cells. LMP-1 was detected in 19/23 EBER positive peripheral T-cell lymphomas (83%). Our results show that EBV is strongly associated with peripheral T-cell lymphomas in Chinese. An important role for the virus is suggested in lymphomas of the nasopharynx. The significance of EBV in T-cell lymphomas that contain only a minor population of virally infected tumour cells is currently unclear.

Deletions within the LMP1 oncogene of Epstein-Barr virus are clustered in Hodgkin's disease and identical to those observed in nasopharyngeal carcinoma.

This study of 52 European patients with Hodgkin's disease (HD) expressing the latent membrane protein 1 (LMP1) oncogene within diagnostic Hodgkin and Reed-Sternberg (HRS) cells was performed to detect LMP1 isolates carrying deletions and to characterize them at a molecular and histologic level. Deletions were identified in 5 cases, clustered near the 3' end of the LMP1 gene, and histologically associated with numerous HRS cells. DNA sequencing showed homology with the deletions seen in the Asian nasopharyngeal carcinoma (NPC) isolates CAO and 1510. Our findings suggest that partial deletions of the LMP1 oncogene, associated with aggressive behavior in NPC CAO and NPC 1510, occur at a particular localization and confer a proliferative phenotype to lymphoid cells in HD.

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.

The association between Epstein-Barr virus and Chinese Hodgkin's disease.

Epstein-Barr virus (EBV) can be detected in Hodgkin and Reed-Sternberg (HRS) cells in about one-half of cases of Hodgkin's disease (HD) in Western countries. To determine whether EBV is also associated with HD in a developing country such as China, we studied paraffin sections from 28 Chinese cases of HD for expression of latent membrane protein-I (LMP-I) and EBV-encoded small RNA (EBER-I), using immuno-histology and RNA/RNA in situ hybridization respectively. The cases were selected from a large series of Chinese lymphomas following histological and immunophenotypical revision. EBV gene expression was found in HRS cells in 17/28 cases, and was related to histological sub-type, being present in 10/11 of mixed cellularity, 6/14 nodular sclerosis, 0/1 lymphocytic predominance, 0/1 lymphocytic depletion, and 1/1 unclassified HD. The 2 methods for detecting EBV gene expression gave similar results, except in one case of nodular sclerosis, in which HRS cells were negative for EBER-I, but weakly positive for LMP-I. In 5/12 cases with EBER-negative HRS cells, rare small or medium-sized lymphocytes expressed EBER-I but not LMP-I. These results suggest that (i) Chinese HD is frequently associated with EBV; (ii) the proportional frequency and sub-type distribution of EBV-positive HD are similar in China and in the West; (iii) both LMP-I immunohistology and EBER in situ hybridization reliably detect EBV in HRS cells in routine biopsies, but the former is simpler and less resource-consuming to perform.

In situ demonstration of Epstein-Barr virus small RNAs (EBER 1) in acquired immunodeficiency syndrome-related lymphomas: correlation with tumor morphology and primary site.

Some acquired immunodeficiency syndrome (AIDS)-related lymphomas (ARLs) are infected with Epstein-Barr virus (EBV), although the frequency and importance of this association is disputed. Using paraffin section RNA in situ hybridization (ISH) with digoxigenin-labeled riboprobes, we screened 16 central nervous system (CNS) non-Hodgkin's lymphomas (NHLs), 101 systemic NHLs, and 11 Hodgkin's disease cases arising in human immunodeficiency virus-seropositive individuals for EBV-encoded small RNA (EBER 1) expression, an EBV gene product transcribed in abundance during latent infection. Tumor cells contained EBV in 85 of 128 ARLs (66%), but infection rates differed with lymphoma type. EBER 1 was expressed in tumor cells in 11 of 11 Hodgkin's disease cases (100%), 15 of 16 CNS NHLs (94%), and 46 of 60 systemic immunoblast-rich/large-cell lymphomas (77%), but in only 12 of 35 Burkitt-type (small noncleaved cell) (34%) and 1 of 6 monomorphic centroblastic (diffuse large noncleaved cell) (17%) lymphomas. In most EBV-positive ARLs, all recognizable viable tumor cells expressed EBER 1. We conclude that (1) EBV infects tumor cells in all AIDS-related Hodgkin's disease cases, in virtually all primary CNS ARLs, and in most systemic immunoblast-rich/large-cell ARLs; (2) only a minority of Burkitt-type and monomorphic centroblastic lymphomas are associated with EBV; and (3) EBER-ISH is ideal for the histopathologic detection of latent EBV in routine tissue specimens.