Deletions in the Epstein-Barr virus latent membrane protein-1 oncogene in Hodgkin's disease

The extent of genetic diversity of Epstein-Barr virus and its geographic and disease patterns: a need for reappraisal

Epstein-Barr virus (EBV) is a ubiquitous, gamma-1 lymphotrophic virus etiologically linked to nasopharyngeal carcinoma (NPC), endemic to Southern China, and Burkitt lymphoma (BL), endemic to equatorial Africa, both of which are rare elsewhere in the world. Why EBV is associated with different malignancies in different geographic regions remains puzzling and may be related to EBV genotypic variability through specific disease and geographic associations. We review the literature on sequence variation in EBV genes, focusing on LMP-1, EBNA-1, and BZLF-1 and their distribution by geography and disease. Given the limitations of current studies, definitive conclusions regarding the link between EBV genotypes, disease and geography are not possible. We suggest that the true extent of EBV diversity is likely to be greater than is currently recognized. Additional studies conducted in carefully selected populations, that are sufficiently powered to provide robust estimates, and that utilize testing approaches that permit full characterization of viral diversity are needed to further our understanding of patterns of EBV genetic variation and their association with malignancies in different regions.

Epstein-Barr virus genetic variation in Vietnamese patients with nasopharyngeal carcinoma: full-length analysis of LMP1

Genetic variation in tumor virus genes and its impact on function might contribute to the understanding of geographic differences in risks for virus-associated tumors. This is particularly true for the genes known to contribute to the biology of the tumor. It is has been proposed that Epstein-Barr virus (EBV) gene variation has a role in the high risk of nasopharyngeal carcinoma (NPC) in South-East Asia. NPC is among the five most common cancers in Vietnam. EBV-NPC cells always express EBV nuclear antigen 1 (EBNA1) and also frequently latent membrane protein 1 and 2 (LMP1 & LMP2). To investigate EBV gene variation in Vietnamese NPC patients we analyzed the full length of LMP1 gene including its promoter region, and the N-termini of both EBNA1 and LMP2A genes from five NPC biopsies. We detected two EBV variants V1 and V2 based on the LMP1 nucleotide sequence pattern compared with the prototype B95-8 and some available sequences including Chinese variants. The V1 variant shows strong similarity to a variant dominant in Southern China (China 1), while the V2 variant is similar to a Thai variant SEA 2 and partly identity with GD1 in the C-terminus. The promoter region and transmembrane domain of the SEA 2-like samples contained some specific differences compared with previously published variants. In contrast, analysis of EBNA1 N- and LMP2A N-termini only revealed minor changes. Our findings reinforces that the polymorphisms of whole LMP1 sequence should be considered in future EBV molecular epidemiology studies in different geographic populations.

Epstein-Barr virus latent membrane protein-1 (LMP-1) 30-bp deletion and Xho I-loss is associated with type III nasopharyngeal carcinoma in Malaysia

BACKGROUND

Nasopharyngeal carcinoma (NPC) is a human epithelial tumour with high prevalence amongst Chinese in Southern China and South East Asia and is associated with the Epstein-Barr virus (EBV). The viral genome harbours an oncogene, namely, the latent membrane protein 1 (LMP1) gene and known variants such as the 30-bp deletion and loss of XhoI restriction site have been found. Less is known about the relationship between these variants and the population characteristics and histological type.

METHODS

In this study, the EBV LMP1 gene variants from 42 NPC and 10 non-malignant archived formalin fixed, paraffin-embedded tissues, as well as plasma from another 35 patients with nasopharyngeal carcinoma were determined by using Polymerase Chain Reaction (PCR). Statistical analysis was performed by using SPSS programme.

RESULTS

LMP1 30-bp deletion was detected in 19/34 (55.9%) of NPC tissues, 7/29 (24.1%) of plasma but absent in non-malignant tissues (8/8). Coexistence of variants with and without 30bp deletion was found only in 5/29 (17.2%) plasma samples but not in NPC tissues. The loss of XhoI restriction site in LMP1 gene was found in 34/39 (87.2%) of the NPC tissues and 11/30 (36.7%) of plasma samples. None of the non-malignant nasopharyngeal tissues (8/8) harbour XhoI-loss variants. LMP1 30-bp deletion was detected in 16/18 Chinese versus 3/15 Malays and 13/16 type III (undifferentiated carcinoma) versus 1/6 type I (keratinizing squamous cell carcinoma). XhoI-loss was found in 19/19 Chinese versus 14/19 Malays and 18/18 type III (undifferentiated) versus 2/5 type I (keratinizing squamous cell carcinoma). Statistical analysis showed that these variants were associated with ethnic race (30-bp deletion, p < 0.05; XhoI-loss, p = 0.046) and histological type of NPC (30-bp deletion, p = 0.011; XhoI-loss, p = 0.006). Nineteen out of 32 NPC tissues (19/32; 59.4%) and 6/24 (25%) of plasma samples showed the coexistence of both the 30-bp deletion and the loss of XhoI restriction site. A significant relationship was found with the Chinese race but not histological type.

CONCLUSION

The incidence rate of 56% for LMP1 30-bp deletion was lower compared to previously reported rates of 75-100% in NPC tissues. Coexistence of variants with and without 30-bp deletion was found only in 5/29 plasma samples. The incidence rate of XhoI restriction site loss in NPC was comparable to other studies from endemic regions such as Southern China. For the first time, the presence of LMP1 30-bp deletion or XhoI-loss was associated with the Chinese race and type III NPC. Both these variants were not found in non-malignant tissues. The influence of these variants on disease progression and outcome in Chinese and type III NPC requires further investigation.

High frequency of a 30-bp deletion of Epstein-Barr virus latent membrane protein 1 gene in primary HIV non-Hodgkin's brain lymphomas

A characteristic 30-base pair (bp) deletion (del) in the 3' end of the Epstein-Barr virus (EBV) latent membrane protein 1 (LMP1) gene, coding for the C-terminal NF-kappa B activation domain, has been identified in various lymphoproliferative disorders and nasopharyngeal carcinomas. In the single report to date of human immunodeficiency virus primary brain lymphomas (HIV-PBLs), del-LMP1 was noted in seven cases out of nine. The present study was designed to identify this deletion in a series of 31 diffuse large B-cell HIV-PBLs, with the aim of determining its possible oncogenic action. The presence of EBV was confirmed by EBER mRNA in situ hybridization. After genomic extraction from frozen tissue, two 20-base oligonucleotide primers flanking the site of the 30-bp deletion were used. DNA sequencing of the polymerase chain reaction (PCR) products confirmed an identical segment spanning 30-bp and 69-bp, frequently associated with mutational hotspots in 19 cases (61%). A role for del-LMP1 in the oncogenic potential of EBV in systemic proliferations is a matter of debate. Its high incidence suggests that the oncogenic mechanism of LMP1 in the brain might differ significantly from that in systemic lymphoid proliferations, and might be enhanced by HIV infection.

Association of Epstein-Barr virus and nasopharyngeal carcinoma in Caucasian patients

We evaluated the association of nasopharyngeal carcinoma (NPC) and Epstein-Barr virus (EBV) in Spanish patients, and studied the expression of EBV products (latent membrane protein-1 [LMP-1] and ZEBRA proteins) by NPC cells and its possible prognostic value. In situ hybridization (ISH) for EBV-encoded nonpolyadenylated RNAs (EBERs) and immunohistochemical expression of LMP-1 and ZEBRA proteins by immunohistochemistry were examined in formalin-fixed, paraffin-embedded NPC specimens from 30 patients, and a survival analysis was done by the Kaplan-Meier method. We detected EBERs by ISH in 96.67% of the NPC cases, and detected expression of LMP-I in 43.33% of the NPC cases and expression of ZEBRA protein in 6.67% of the NPC cases. We conclude that ISH for expression of EBERs is an adequate method for detection of EBV in NPC. LMP-1 is not frequently expressed in NPC cells (43.33%). Most NPC cells carry a latent EBV infection. LMP-1 expression might have worsened the prognosis of NPC in our series.

Epstein-Barr virus associated lymphoproliferations in the AIDS setting

Epstein-Barr virus (EBV) is a ubiquitous gammaherpesvirus that is associated with a variety of malignancies. In vivo infection of B lymphocytes is initially associated with the broad expression of immunodominant viral latency genes and proliferation of infected cells. Ultimately, a viral reservoir is established in resting B cells with restricted expression of viral latency genes and no expression of immunodominant viral genes. Among the tumours associated with EBV that are relevant to a consideration of EBV in HIV-associated malignancies are posttransplant lymphoproliferative disease, Burkitt's lymphoma (BL) and Hodgkin's disease (HD). BL carries whereas EBV in only a minority of cases whereas HD in patients infected with HIV is virtually always EBV-associated. EBV-directed T cell therapies have proven effective in posttransplant lymphomas in bone marrow transplantation patients. In patients with HIV infection, primary central nervous system (CNS) and immunoblastic lymphomas show similarities with posttransplant lymphoproliferative disease. EBV detection studies in cerebrospinal fluid are useful diagnostically in primary CNS lymphoma. T cell therapies may be useful in the treatment of EBV-associated lymphomas. Thus, a better understanding of the relationship between EBV and these tumours will not only help to clarify their pathogenesis, but may facilitate the development of new diagnostic and therapeutic strategies.

Pathogenetic and histogenetic features of HIV-associated Hodgkin's disease

Compared with the cases in the general population, Hodgkin's disease (HD) arising in the HIV setting shows distinctive features in terms of epidemiology, aetiopathogenesis, histopathology and clinical behaviour. Although HD does not represent an AIDS-defining condition, recent evidence consistently indicates that HIV-infected individuals have a significantly increased risk of developing HD. HIV-related HD is characterised by the preponderance of aggressive histological subtypes, advanced stage at presentation, and highly malignant clinical course. Moreover, unlike HD in the general population, the large majority of HIV-related HD cases are pathogenetically linked to Epstein-Barr virus (EBV), with rates of EBV positivity ranging from 80 to 100%. Hodgkin and Reed-Sternberg cells of these cases invariably show a strong expression of the EBV-encoded latent membrane protein-1 (LMP-1), which functions as a constitutively activated tumour necrosis factor (TNF) receptor-like molecule. Usurpation of physiologically relevant pathways by LMP-1 may lead to the simultaneous or sequential activation of signalling pathways involved in the promotion of cell activation, growth, and survival, contributing thus to most of the features of HIV-related HD.

Deletions within the epstein-barr virus latent membrane protein-1 oncogene in adult ordinary, HIV-associated and paediatric Hodgkin's disease

The aims of this study were the following: a) to perform Epstein-Barr virus (EBV) strain type assignment in three groups of Hodgkin's disease(HD): adult ordinary (39 cases), paediatric (24 cases), and HIV-associated (30 cases) and to compare the prevalence of type 1 and type 2 in each of the groups with that existing in two reference populations made up of 50 adults and 39 children; b) to assess the frequency of latent membrane protein-1 (LMP-1) 30-base pair (bp) deletions in the HD groups and in the healthy controls; and c) to relate the presence of LMP-1 deletions with EBV type. Type 2 EBV was observed in 12.8% of ordinary HD, in 26.7% of HIV-associated HD, in 25% of paediatric HD, in 4% of adult controls, and in none of the healthy children. The existence of double infections by type 1 and 2 EBV was also observed in 5.1% of ordinary HD, in 6.7% of HIV-associated HD, and in 10% of adult controls. The 30-bp deletion was identified overall in 33.3% of ordinary HD, in 83.3% of HIV-positive HD, 79.2% of paediatric HD, 34.7% of adult controls, and 36.4% of healthy children. Statistical analysis showed a significant association of the deleted strains with HD occurring in HIV-positive patients (P= 0.00003) and childhood HD (P= 0.006). On the other hand, the prevalence of the 30-bp deletion in the adult ordinary HD group reflects the prevalence of the deletion in the general population. Co-infections by deleted and non-deleted EBV strains were detected in 12.8% of ordinary HD, in 33.3% of HIV-associated HD, in 50% of paediatric HD, in 26.5% of adult controls, and in 27.3% of healthy children. Concerning the relationship between the deletion and the EBV typing, 26% of type 1 specimens carried the 30-bp deletion in an isolated manner compared with 64.7% of type 2. The statistical analysis showed that the deletion was associated with type 2 strains when coinfections were excluded and only the cases in which the deletion appeared alone were considered (P=0.003).

Analysis of the Epstein-Barr virus (EBV) latent membrane protein 1 (LMP-1) gene and promoter in Hodgkin's disease isolates: selection against EBV variants with mutations in the LMP-1 promoter ATF-1/CREB-1 binding site

AIMS

To study the distribution of Epstein-Barr virus (EBV) variants containing mutations in the latent membrane protein 1 (LMP-1) oncogene and promoter in EBV associated Hodgkin's disease and infectious mononucleosis compared with previous findings in asymptomatic EBV carriers.

METHODS

Sequence analysis of the EBV LMP-1 promoter and gene in isolates from Danish patients with Hodgkin's disease (n = 61) and infectious mononucleosis (n = 10).

RESULTS

Viruses (previously designated group D) that contain two mutations in the activating transcription factor/cAMP response element (ATF/CRE) in the LMP-1 promoter, which are known to decrease promoter activity greatly, were significantly less frequent in Hodgkin's disease than in both infectious mononucleosis (p = 0.0081) and asymptomatic EBV carriers (p = 0.0084). In some cases, the LMP-1 gene contained mutations in a recently identified cytotoxic T cell (CTL) epitope. Most viral isolates contained mutations shown to increase nuclear factor kappa B (NF-kappa B) activation and had one of two newly identified C-terminal activation regions 3 (CTAR-3) deleted. The exon 1 Xho-I restriction site in the LMP-1 gene could be lost through a range of different mutations.

CONCLUSIONS

These findings indicate selection pressure against EBV strains with weak LMP-1 promoter activity in Hodgkin's disease and thus provide further strong circumstantial evidence for the pathogenic role of EBV (and LMP-1) in this disease. Mutation of the CTL epitope suggests immune selection of EBV strains. Many EBV isolates contain functionally important mutations in the LMP-1 gene. Loss of the Xho-I restriction site should not be used as a marker of specific LMP-1 variants.

Recent advances in the molecular pathogenesis of lymphomas

Most human lymphomas remain heterogeneous biologic entities in spite of recent advances in the description of their clinical presentation, cellular morphology, immunophenotype, and genotype. Elucidation of genetic alterations causing malignant transformation may explain pathogenesis, refine differential diagnosis, clarify prognosis, and provide rational basis for new therapy. During the last year the expression of anaplastic lymphoma kinase clarified presentation and provided clues toward the outcome of anaplastic large cell lymphoma; the breakpoints of t(2;5) were mapped; constitutive activation of anaplastic lymphoma kinase by a chromosomal inversion was described; transformation was shown to be independent of nuclear localization of anaplastic lymphoma kinase; and phospholipase C-gamma was identified as a molecular target for the kinase activity of anaplastic lymphoma kinase. Molecular characterization of recurrent chromosome abnormalities has identified new candidate oncogenes: bcl-9, bcl-10, PAX-5, MMSET, and c-maf. Their precise role in malignant transformation, and the frequency of their alteration in lymphoma and myeloma, is not yet defined. The expression of the antiapoptotic protein bcl-2 on aggressive lymphomas was shown to be associated with inferior disease-free survival by several investigators. This may be a target of pharmacologic reduction of bcl-2 levels. Can these advances in molecular pathogenesis improve cure rates for lymphoma? The spectacularly successful molecular modeling of inhibitors for HIV protease suggests that this may be an attainable objective.

Biologically relevant phenotypic changes and enhanced growth properties induced in B lymphocytes by an EBV strain derived from a histologically aggressive Hodgkin's disease

Epstein-Barr virus (EBV) isolates show a wide genomic heterogeneity, and a key issue is whether distinct strain variations may contribute to the development and/or malignancy of EBV-related disorders. Herein, we report on the virologic and biologic characterization of an EBV strain derived from a cyto-histologically aggressive EBV-related Hodgkin's disease (HD) (case HD-3) showing a high number of "anaplastic" Reed-Sternberg cells expressing markedly high levels of CD30, CD40 and LMP-1. The HD-3-derived EBV showed strong in vitro immortalizing properties, as suggested by the unusually high number of spontaneous lymphoblastoid cell lines (LCLs) obtained from the patient. Immunofluorescence and immuno-cytochemical analyses showed that HD-3 LCLs expressed significantly higher levels of CD23, CD30, CD38, CD39, CD40 and CD71 antigens and CD54 and CD58 adhesion molecules than B95.8 LCLs. In contrast, the expression of CD11a, CD24, CD95, bcl-2, LMP-1 and EBNA-2 was similar in both groups of LCLs. These phenotypic changes are consistent with the induction of a pronounced activation status and are not dependent on the cellular background, having been closely reproduced by the same virus in LCLs from an unrelated donor (DEN-HD-3 LCLs). HD-3 LCLs were able to grow in vitro at low serum concentrations (up to 0.1%) and were significantly more clonogenic in soft agarose than B95.8 LCLs. Moreover, although no evidence of tumor formation was observed in nude mice injected with B95.8 LCLs, all 5 spontaneous LCLs of patient HD-3 and the 2 DEN-HD-3 LCLs grew in transplanted animals as lymphoproliferations composed of EBER+, LMP-1+ cells. Our findings indicate that the biologic properties of the HD-3 EBV strain are significantly different from those of the B95.8 virus and may have contributed to the cytologic and histo-pathologic malignancy of this HD case. Moreover, molecular characterization of the HD-3 EBV genome identified a 63-bp deletion within the 3' end of the LMP-1 gene as a likely significant change that may be responsible, at least in part, for the biologically relevant phenotypic modifications and enhanced in vitro and in vivo growth potential induced in B lymphocytes by this virus strain.

Epstein-Barr virus in the pathogenesis of Hodgkin's disease

Epidemiologic and clinico-pathologic features of Hodgkin's disease suggest that an infectious agent may be involved in the pathogenesis of this puzzling disorder. Recently accumulated data provide direct evidence supporting a causal role of Epstein-Barr virus in a significant proportion of cases. In addition to allowing a better understanding of the complex pathogenesis of Hodgkin's disease, these virological advances, briefly reviewed herein, also constitute an important basis for the development of new therapeutic strategies.

Deletion of Epstein-Barr virus latent membrane protein 1 gene in United States and Brazilian Hodgkin's disease and reactive lymphoid tissue: high frequency of a 30-bp deletion

A 30-basepair (bp) deletion in the Epstein-Barr virus (EBV) latent membrane protein 1 (LMP1) gene has been reported in nasopharyngeal carcinoma and EBV-associated malignant lymphomas. Prior studies have found the deletion in about 10% to 28% of cases of Hodgkin's disease (HD), particularly in cases with aggressive histology. We studied the prevalence of 30-bp LMP1 gene deletion in EBV-positive HD in the United States (US) (12 cases) and Brazil (26 cases) with comparison to reactive lymphoid tissues (21 cases) and HD without EBV-positive Reed-Sternberg cells (15 cases). We studied the status of the LMP1 gene by Southern blot hybridization of polymerase chain reaction (PCR) products obtained after amplification with primers spanning the site of the deletion. We also performed EBV typing, EBER1 in situ hybridization, and LMP1 protein immunohistochemistry. EBV was detected in 12/26 (46%) cases of HD from the US and 26/27 (96%) cases of Brazilian HD. The 30-bp LMP1 gene deletion was observed in 4/12 (33%) cases of EBV-positive HD from US, and 12/26 (46%) cases of Brazilian EBV-positive HD, including 3 cases of type B EBV, as compared with 12/21 (57%) reactive lymphoid tissues and 9/15 (60%) cases of EBV-negative HD. US and Brazilian HD showed a higher prevalence of the 30-bp LMP1 gene deletion, compared with studies of others. The unexpected finding of high incidence of 30-bp deletion in LMP1 gene in reactive lymphoid tissue and HD without EBV-positive Reed-Sternberg cells suggests that this deletion may not be relevant to HD pathogenesis in most cases.

Epstein-Barr virus latent membrane protein-1 oncogene deletion in post-transplantation lymphoproliferative disorders

Epstein-Barr virus (EBV) latent membrane protein 1 (LMP1) is a multifunctional oncoprotein. A 30-bp deletion of the 3' end of the LMP1 gene (del-LMP1) has been identified in some EBV isolates. This deleted LMP1 gene encodes a protein, altered on the carboxy terminus, which is thought to have greater oncogenic potential than the wild type. Recently, it was suggested that del-LMP1 plays a role in the development of malignant lymphomas occurring in immunocompromised patients. To further elucidate the role of del-LMP1 in post-transplantation lymphoproliferative disorders (PT-LPDs) we analyzed 58 PT-LPD lesions from 36 heart and kidney organ transplant recipients. Overall, del-LMP1 was detected in 44% of the cases. Four plasmacytic hyperplasias (36%), eight polymorphic B-cell hyperplasias/polymorphic B-cell lymphomas (38%), and five malignant lymphomas/multiple myelomas (71%) exhibited del-LMP1. Two of the three patients displaying disease progression showed wild-type LMP1 gene (w-LMP1) and one showed del-LMP1. LMP1 status remained the same in all three patients during disease progression. In patients undergoing biopsy of multiple separate PT-LPD lesions representing different clonal lymphoid proliferations, LMP1 status was the same in all of the lesions in each patient. Furthermore, although the polyclonal lesions harbor multiple EBV infectious events, they either showed w- or del-LMP1 but not both. Analysis of the tissues without an apparent PT-LPD (peripheral blood, bone marrow, or colon) revealed EBV and LMP1 type identical to that found in the lesions. In conclusion, the presence or absence of del-LMP1 in PT-LPDs does not correlate with the histopathological category or the malignant nature of the lymphoid proliferation. LMP1 status does not change during disease progression and is the same within multiple lesions occurring in the same patient regardless of their clonal relationship. These findings suggest that 1) EBV infection in patients with PT-LPDs occurs with a w- or del-LMP1-type EBV isolate and does not change once a patient acquires the virus and 2) the infection is an early event in the development of PT-LPDs and transformation is induced regardless of the type of LMP1.

Prevalence of mutations and 30-bp deletion in the C-terminal region of Epstein-Barr virus latent membrane protein-1 oncogene in reactive lymphoid tissue and non-nasopharyngeal EBV-associated carcinomas in Hong Kong Chinese

A specific variant of Epstein-Barr virus (EBV) with a 30-bp deletion in the C-terminal region of the LMP1 gene has been found in some EBV-associated malignancies. To better understand the tumorigenic role of this LMP1 variant, we used PCR and sequencing to examine the LMP1 gene in 38 EBV-associated carcinomas (EBV-CAs) occurring in various organs (6 lung, 10 salivary gland, 5 sino-nasal, 16 gastric and 1 metastatic NPC), 55 reactive lymphoid tissues from tonsils (TON) and 67 EBV-negative tumours in various organs (22 adenolymphoma of salivary gland, 14 gastric and 31 colonic adenocarcinomas), where the virus was demonstrated in lymphocytes. The TON showed prevalence of both deleted and non-deleted variants of LMP1, with dual infection being common. Significantly more of the LMP1 variant was deleted in EBV-CA and in EBV-negative tumours. Sequencing showed that the deleted and non-deleted variants have different sets of amino acid mutation. Mutations in codon 344 and 355 in the non-deleted variant disrupted the 9 nucleotide repeat flanking the deletion and thus may have conferred resistance to the deletion. The prevalence of both variants in the TON, with enrichment for the deleted variant in various organs, argues for the existence of an immune selection pressure in our population. The deleted variant, which may have a higher tumorigenic potential, may contribute to the high incidence of NPC, as well as the occurrence of EBV-CA in organs outside the nasopharynx in our locality.

Deletion variants within the NF-kappaB activation domain of the LMP1 oncogene in acquired immunodeficiency syndrome-related large cell lymphomas, in prelymphomas and atypical lymphoproliferations

The latent membrane protein 1 (LMP1) oncogene of Epstein Barr virus (EBV) is expressed in tumor cells of acquired immunodeficiency syndrome (AIDS) related lymphomas, HIV-negative, EBV-associated malignant lymphoproliferations, nasopharyngeal carcinoma, as well as in reactive immunoblasts of infectious mononucleosis. Naturally occurring LMP1 deletion variants (LMP1-del), characterized by clustered mutations and a distinct 30 base pair deletion within the carboxy terminal domain of LMP1, essential for maximal NF-kappaB stimulation, have been identified in the same conditions. These variants prevail in AIDS-related lymphomas, and are associated with clinically aggressive behaviour in HIV-negative lymphomas, and are frequent in prelymphomatous and reactive states. Functional studies showing a growth advantage of cells infected by these variants may explain the accumulation of LMP1-del in these entities. In the carboxy terminal NF-kappaB activation domain of LMP1, evidence of a hypervariable region close to the highly conserved 23 outermost amino acids essential for malignant transformation, may reflect the natural selection of growth promoting variants involved in signalling pathways. The prevalence of the same mutational pattern in AIDS-related lymphoma as well as in hyperplastic reactive states and prelymphomas supports the hypothesis that these variants confer a growth advantage manifested under impaired cellular immunity.

Pathological, immunological, and molecular features of Hodgkin's disease associated with HIV infection. Comparison with ordinary hodgkin's disease

The aim of the present study was to analyze in a series of 24 HIV-positive Hodgkin's disease (HD) patients the morphological and immunological features, the presence of rearrangements in the immunoglobulin heavy chain (IgH) gene, expression of the Epstein-Barr virus (EBV) latent membrane protein-1 (LMP-1), and the existence of deletions in the intracytoplasmic domain of the LMP-1 gene. The results obtained were compared with those from a parallel series of 56 patients with ordinary HD. Briefly, comparison of the two series showed a predominance of unfavorable histological subtypes in HIV-positive HD patients. The mixed cellularity subtype was more frequent in HIV-positive than in HIV-negative HD patients: the difference in percentage was statistically significant (p = 0.04). Neoplastic cell-rich cases were significantly more frequent (p = 0.40) in HIV patients (59%) than in ordinary HD patients (34%). In 25% of HIV-infected and in 14% of ordinary HD patients, the neoplastic cells were CD20+, a difference that was not statistically representative. Clonal IgH rearrangements were detected in 33% of HIV-infected patients and in 23% of ordinary HD patients, a nonsignificant difference. LMP-1 expression was detected in 100% of HIV-positive patients and in 57% of ordinary HD patients (p = 0.004). A 30-base-pair deletion in the carboxy-terminal domain of the LMP-1 gene was found in 16 of 18 HIV-infected patients (89%), whereas it was identified in only 8 of 25 ordinary HD patients (32%) (p = 0.008). In conclusion, HD in HIV-infected patients as compared with HD in HIV-negative individuals is associated with morphological features of aggressivity, with a higher frequency of neoplastic cells, and with constant LMP-1 expression. The fact that LMP-1 is expressed in all HIV-infected patients suggests that EBV plays an etiological role in the pathogenesis of HIV-associated HD. Furthermore, the presence of EBV strains carrying deletions near the 3' end of the LMP-1 gene in the majority of cases may be related with the morphological and clinical aggressivity of HD in immunocompromised patients.