Treatment options for post-transplant lymphoproliferative disorder and other Epstein-Barr virus-associated malignancies

EBV and Lymphomagenesis

The clinical significance of Epstein–Barr virus (EBV) cannot be understated. Not only does it infect approximately 90% of the world’s population, but it is also associated with numerous pathologies. Diseases linked to this virus include hematologic malignancies such as diffuse large B-cell lymphoma, Hodgkin lymphoma, Burkitt lymphoma, primary CNS lymphoma, and NK/T-cell lymphoma, epithelial malignancies such as nasopharyngeal carcinoma and gastric cancer, autoimmune diseases such as multiple sclerosis, Graves’ disease, and lupus. While treatment for these disease states is ever evolving, much work remains to more fully elucidate the relationship between EBV, its associated disease states, and their treatments. This paper begins with an overview of EBV latency and latency-associated proteins. It will then review EBV’s contributions to select hematologic malignancies with a focus on the contribution of latent proteins as well as their associated management.

CAR T Cell Therapy: A Game Changer in Cancer Treatment

The development of novel targeted therapies with acceptable safety profiles is critical to successful cancer outcomes with better survival rates. Immunotherapy offers promising opportunities with the potential to induce sustained remissions in patients with refractory disease. Recent dramatic clinical responses in trials with gene modified T cells expressing chimeric antigen receptors (CARs) in B-cell malignancies have generated great enthusiasm. This therapy might pave the way for a potential paradigm shift in the way we treat refractory or relapsed cancers. CARs are genetically engineered receptors that combine the specific binding domains from a tumor targeting antibody with T cell signaling domains to allow specifically targeted antibody redirected T cell activation. Despite current successes in hematological cancers, we are only in the beginning of exploring the powerful potential of CAR redirected T cells in the control and elimination of resistant, metastatic, or recurrent nonhematological cancers. This review discusses the application of the CAR T cell therapy, its challenges, and strategies for successful clinical and commercial translation.

Antiherpesvirus activities of two novel 4'-thiothymidine derivatives, KAY-2-41 and KAH-39-149, are dependent on viral and cellular thymidine kinases

The emergence of drug-resistant herpesviruses represents a significant problem in clinical practice, primarily in immunocompromised patients. Furthermore, effective antiviral therapies against gammaherpesvirus-associated diseases are lacking. Here, we present two thiothymidine derivatives, KAY-2-41 and KAH-39-149, with different spectra of antiviral activity from those of the reference antiherpetic drugs, showing inhibitory activities against herpes simplex virus, varicella-zoster virus (VZV), and particularly against Epstein-Barr virus, with high selectivity in vitro. While KAY-2-41- and KAH-39-149-resistant herpesviruses were found to harbor mutations in the viral thymidine kinase (TK), these mutations conferred only low levels of resistance to these drugs but high levels to other TK-dependent drugs. Also, antiviral assays in HeLa TK-deficient cells showed a lack of KAY-2-41 and KAH-39-149 activities against herpes simplex virus 1 (HSV-1) and HSV-2 TK-deficient mutants. Furthermore, enzymatic TK assays showed the ability of HSV-1 TK, VZV TK, and cellular TK1 and TK2 to recognize and phosphorylate KAY-2-41 and KAH-39-149. These results demonstrate that the compounds depend on both viral and host TKs to exert antiviral activity. Additionally, the antiviral efficacy of KAH-39-149 proved to be superior to that of KAY-2-41 in a mouse model of gammaherpesvirus infection, highlighting the potential of this class of antiviral agents for further development as selective therapeutics against Epstein-Barr virus.

Post-transplant lymphoproliferative disorders and other malignancies after pediatric intestinal transplantation: incidence, clinical features and outcome

PTLDs are a well-recognized and potentially fatal complication after intestinal transplantation. We analyzed the incidence, clinical features, and outcome in a 63 intestinal transplantation series performed in our unit between October 1999 and July 2011. Types of graft included ISB (n = 23), LSB (n = 20), and MV (n = 20). Patients were categorized into three groups of immunosuppression: I (n = 43) received basiliximab, tacrolimus, and steroids; II (n = 11) thymoglobulin and tacrolimus, and III (n = 9) alemtuzumab and tacrolimus. EBV status was serially assessed. All PTLD cases were biopsied to establish histopathological diagnosis. The incidence of PTLD was 14.2% (9/63). Median onset of PTLD after transplant was four months (range: 0.5-28), within first postoperative year in 6 (66.6%) patients. Fever was the most common symptom. Graft removal was needed in four patients (44%). The patient survival rate was 66.6% (6/9). We have not found any association between PTLD and immunosuppression regimen or transplant type. However, there was a statistical association with EBV active infection.

Burkitt lymphoma in Papua New Guinea—40 years on

BACKGROUND

Burkitt lymphoma is common in tropical Africa and Papua New Guinea, where it has been reported to account for 16% of all childhood malignancies.

AIM

This study aimed to compare the geographical distribution of recent cases and their anatomical site of presentation with findings from previous studies, and to determine survival using the current treatment protocol.

METHODS

The study included all cases of Burkitt and Burkitt-like lymphoma in children up to 14 years of age diagnosed between January 1998 and December 2003.

RESULTS

Thirty-six children were diagnosed with Burkitt lymphoma, accounting for 50% of all lymphomas and 13% of all childhood malignancies. The median age was 6 years (interquartile range 4-8 years) and the male:female ratio was 8:1. Facial structures were the most commonly affected sites, accounting for 21 (58%) cases, followed by spinal involvement in three. The majority (89%) of patients came from malaria-holo-endemic, coastal PNG and three were from the highland region. The national incidence was 1.7/100,000 but provincial rates varied, the highest of 13.4/100,000 being in Gulf province. Only two of the 16 patients who received chemotherapy were known to be in remission at 12 months.

CONCLUSIONS

Burkitt tumour remains a common childhood malignancy in PNG. There is a need to improve diagnosis and reporting so that treatment can be started early. The most appropriate treatment regimen for use in PNG and other resource-poor countries remains to be determined.

Sustained response to intrathecal rituximab in EBV associated Post-transplant lymphoproliferative disease confined to the central nervous system following haematopoietic stem cell transplant

Post-transplant lymphoproliferative disorder (PTLD) in the central nervous system (CNS) is a very rare complication of haematopoietic stem cell transplant (HSCT) and has a dismal prognosis. We report the successful treatment of this disorder with intrathecal rituximab therapy in two children who developed isolated CNS PTLD after HSCT. These children had failed to respond to standard chemotherapy, intravenous rituximab and EBV specific cellular therapy.

Lymphoproliferative disorders after solid organ transplantation-classification, incidence, risk factors, early detection and treatment options

Posttransplant lymphoproliferative disorder (PTLD) is a heterogeneous disease group of benign and malignant entities. The new World Health Organisation classification introduced in 2008 distinguishes early lesions, polymorphic, monomorphic and classical Hodgkin lymphoma-type PTLD. Based on the time of appearance, early and late forms can be identified.PTLDs are the second most frequent posttransplantation tumors in adulthood, and the most frequent ones in childhood. The incidence varies with the transplanted organ-from 1%-2% following kidney transplantation to as high as 10% following thoracic organ transplantation-due to different intensities in immunosuppression. Immunocompromised state and Epstein-Barr virus (EBV) infection are the two major risk factors.In Europe and the US approximately 85% of PTLDs are of B-cell origin, and the majority are EBV-associated. Symptoms are often unspecific; extranodal, organ manifestations and central nervous system involvement is common. Early lesions respond well to a decrease in immunosuppression. Malignant entities are treated with rituximab, chemotherapy, radiotherapy and surgical therapy. Adoptive T-cell transfer represents a promising therapeutic approach. The prognosis is favorable in early PTLD, and poor in late PTLD. Five-year survival is 30% for high-grade lymphomas. The prognosis of EBV-negative lymphomas is worse.Lowering the risk of PTLD may be achieved by low dose maintenance immunosuppression, immunosuppressive drugs inhibiting cell proliferation, and special immunotherapy (e.g. interleukin-2 inhibitors). Early detection is especially important for high risk-e.g. EBV-negative-patients, where the appearance of EBV-DNA and the increase in its titer may help.

Dendritic cells loaded with tumor B cells elicit broad immunity against murine gammaherpesvirus 68 but fail to prevent long-term latency

It is still unknown whether a noninfectious gammaherpesvirus vaccine is able to prevent or reduce virus persistence. This led us to use dendritic cells loaded with tumor B cells as a vaccine approach for the murine gammaherpesvirus 68 (gammaHV68) model of infection. Dendritic cells loaded with UV-irradiated latently infected tumor B cells induce broad, strong, and long-lasting immunity against gammaHV68. Dendritic cell vaccination prevents the enlargement of lymph nodes and severely limits acute infection and early latency but does not prevent gammaHV68 from establishing long-term latency. Our findings support the concept that attenuated viruses may be the best vaccine option for preventing gammaherpesvirus persistence.

EBV-associated post-transplantation B-cell lymphoproliferative disorder following allogenic stem cell transplantation for acute lymphoblastic leukaemia: tumor regression after reduction of immunosuppression--a case report

Epstein-Barr virus (EBV)-associated B-cell post-transplantation lymphoproliferative disorder (PTLD) is a severe complication following stem cell transplantation. This is believed to occur as a result of iatrogenic immunosuppression leading to a relaxation of T-cell control of EBV infection and thus allowing viral reactivation and proliferation of EBV-infected B-lymphocytes. In support of this notion, reduction of immunosuppressive therapy may lead to regression of PTLD.We present a case of an 18-year-old male developing a monomorphic B-cell PTLD 2 months after receiving an allogenic stem cell transplant for acute lymphoblastic leukemia. Reduction of immunosuppressive therapy led to regression of lymphadenopathy. Nevertheless, the patient died 3 months afterwards due to extensive graft-vs.-host-disease and sepsis. As a diagnostic lymph node biopsy was performed only after reduction of immunosuppressive therapy, we are able to study the histopathological changes characterizing PTLD regression. We observed extensive apoptosis of blast cells, accompanied by an abundant infiltrate comprising predominantly CD8-positive, Granzyme B-positive T-cells. This observation supports the idea that regression of PTLD is mediated by cytotoxic T-cells and is in keeping with the observation that T-cell depletion, represents a major risk factor for the development of PTLD.

A novel haplo-identical adoptive CTL therapy as a treatment for EBV-associated lymphoma after stem cell transplantation

Epstein-Barr virus (EBV)-related malignancies such as post-transplant lymphoproliferative disease (PTLD) are severe complications after allogeneic stem cell transplantation and solid-organ transplantation. In immunosuppressed transplant recipients, the activity of EBV-specific CTLs are often decreased or absent which leads to an increased risk of developing PTLD. If primary treatment modalities of PTLD fail, the most efficient way of treating the malignancy is adopting EBV-specific CTLs from the donor or, more recently, third-party donors. However, both are time consuming and expensive and often it is too late to administer cells to the patient. We have for the first time, using a rapid isolation protocol of EBV-specific T cells, treated and cured a patient suffering from PTLD with multiple-associated tissue lesions, using her haplo-identical mother as a donor. This treatment approach paves way for a new possibility to within-days treat patients with life-threatening EBV-associated malignancies.

Integrative urinary peptidomics in renal transplantation identifies biomarkers for acute rejection

Noninvasive methods to diagnose rejection of renal allografts are unavailable. Mass spectrometry followed by multiple-reaction monitoring provides a unique approach to identify disease-specific urine peptide biomarkers. Here, we performed urine peptidomic analysis of 70 unique samples from 50 renal transplant patients and 20 controls (n = 20), identifying a specific panel of 40 peptides for acute rejection (AR). Peptide sequencing revealed suggestive mechanisms of graft injury with roles for proteolytic degradation of uromodulin (UMOD) and several collagens, including COL1A2 and COL3A1. The 40-peptide panel discriminated AR in training (n = 46) and test (n = 24) sets (area under ROC curve >0.96). Integrative analysis of transcriptional signals from paired renal transplant biopsies, matched with the urine samples, revealed coordinated transcriptional changes for the corresponding genes in addition to dysregulation of extracellular matrix proteins in AR (MMP-7, SERPING1, and TIMP1). Quantitative PCR on an independent set of 34 transplant biopsies with and without AR validated coordinated changes in expression for the corresponding genes in rejection tissue. A six-gene biomarker panel (COL1A2, COL3A1, UMOD, MMP-7, SERPING1, TIMP1) classified AR with high specificity and sensitivity (area under ROC curve = 0.98). These data suggest that changes in collagen remodeling characterize AR and that detection of the corresponding proteolytic degradation products in urine provides a noninvasive diagnostic approach.

Clinical, phenotypic and genetic similarities and disparities between post-transplant and classical Hodgkin lymphomas with respect to therapeutic targets

OBJECTIVE

Post-transplant Hodgkin lymphoma (ptHL) is a rare but serious complication. We explored the clinical, phenotypic and genetic similarities and disparities between ptHL and classical Hodgkin lymphoma (cHL) in immunocompetent patients and sought proteins/pathways in ptHL that might have potential as therapeutic targets.

RESEARCH DESIGN AND METHODS

Eight ptHL cases in solid organ recipients (mean patient age 36 years; mean duration between organ transplant and onset of ptHL 80 months) were phenotypically and genotypically analyzed and the results were compared with known phenotypic and molecular characteristics of cHL.

RESULTS

All ptHL expressed CD15, CD30 and LMP-1 of EBV; the B-cell markers BOB-1, Oct2, CD79a and CD20 were more commonly expressed in ptHL versus cHL (100%, 86%, 50% and 38% in ptHL compared to 6%, 14%, 10% and 33% in cHL, respectively); all ptHL expressed phosphoinositide 3-kinase (PI3K) versus 81% of cHL; 2/6 (33%) ptHL displayed gains at 9p24 that were similar to cHL (32%). The JAK2 downstream pSTAT3 slightly predominated in ptHL versus cHL (60% versus 50%). Clonal immunoglobulin gene rearrangements were found in 2/4 cases.

CONCLUSIONS

ptHL and cHL are closely related, but not identical, neoplasms, with the primary differences being the strict association with EBV infection, persistent phenotypic B-cell signature and high expression of PI3K as well as the slightly CD4-depleted but TIA-1/Granzyme B-enriched cellular background composition in ptHL.

An overview of the pathogenesis and natural history of post-transplant T-cell lymphoma (corrected and republished article originally printed in Leukemia & Lymphoma, June 2007; 48(6): 1237 – 1241)

Post-transplantation lymphoproliferative disorders (PTLDs) are well recognized complications of solid organ transplantation. The vast majority of early PTLDs are B-cell non-Hodgkin lymphomas. PTLDs of T-cell origin occur much less frequently and account for only a minority of cases. T-cell PTLDs have been reported to occur primarily at extranodal sites, commonly affecting bone marrow or splenic tissues. The small bowel is an uncommon site of origin of these tumors with only seven cases of primary intestinal post-transplant T-cell lymphomas reported in the literature. We hereby report a new case of primary intestinal post-transplant T-cell lymphoma, arising 18 years following renal transplantation, along with a literature review of all published cases.

Epstein-Barr virus nuclear antigen 1-specific CD4+ T cells directly kill Epstein-Barr virus-carrying natural killer and T cells

Epstein-Barr virus (EBV) nuclear antigen (EBNA)1 is expressed in every EBV-infected cell, regardless of the state of EBV infection. Although EBNA1 is thought to be a promising antigen for immunotherapy of all EBV-associated malignancies, it is less clear whether EBNA1-specific CD4(+) T cells can act as direct effectors. Herein, we investigated the ability of CD4(+) T-cell clones induced with overlapping peptides covering the C-terminal region of EBNA1, and identified minimal epitopes and their restricted major histocompatibility complex class II molecules. Of these, a novel epitope, EYHQEGGPD, was found to be presented by DRB1*0401, 0403 and 0406. Five CD4(+) T-cell clones recognized endogenously processed and presented antigens on EBV-transformed lymphoblastoid cell lines (LCL) and one example proved capable of killing EBV-carrying natural killer (NK) and T-cell lines derived from patients with chronic active EBV infection (CAEBV). Identification of minimal epitopes facilitates design of peptide-based vaccines and our data suggest that EBNA1-specific CD4(+) T cells may play roles as direct effectors for immunotherapy targeting EBV-carrying NK and T-cell malignancies.

The regulatory T cell-associated transcription factor FoxP3 is expressed by tumor cells

FoxP3 is a member of the forkhead family of transcription factors critically involved in the development and function of CD25(+) regulatory T cells (Treg). Until recently, FoxP3 expression was thought to be restricted to the T-cell lineage. However, using immunohistochemistry and flow cytometric analysis of human melanoma tissue, we detected FoxP3 expression not only in the tumor infiltrating Treg but also in the melanoma cells themselves. FoxP3 is also widely expressed by established human melanoma cell lines (as determined by flow cytometry, PCR, and Western blot), as well as cell lines derived from other solid tumors. Normal B cells do not express FoxP3; however, expression could be induced after transformation with EBV in vitro and in vivo, suggesting that malignant transformation of healthy cells can induce FoxP3. In addition, a FOXP3 mRNA variant lacking exons 3 and 4 was identified in tumor cell lines but was absent from Treg. Interestingly, this alternative splicing event introduces a translation frame-shift that is predicted to encode a novel protein. Together, our results show that FoxP3, a key regulator of immune suppression, is not only expressed by Treg but also by melanoma cells, EBV-transformed B cells, and a wide variety of tumor cell lines.

Immunodominance of lytic cycle antigens in Epstein-Barr virus-specific CD4+ T cell preparations for therapy

BACKGROUND

Epstein-Barr virus (EBV) is associated with a number of human malignancies. EBV-positive post-transplant lymphoproliferative disease in solid organ and hematopoietic stem cell transplant recipients has been successfully treated by the adoptive transfer of polyclonal EBV-specific T cell lines containing CD4+ and CD8+ T cell components. Although patients receiving T cell preparations with a higher CD4+ T cell proportion show better clinical responses, the specificity of the infused CD4+ component has remained completely unknown.

METHODOLOGY/PRINCIPAL FINDINGS

We generated LCL-stimulated T cell lines from 21 donors according to clinical protocols, and analyzed the antigen specificity of the CD4+ component in EBV-specific T cell preparations using a genetically engineered EBV mutant that is unable to enter the lytic cycle, and recombinantly expressed and purified EBV proteins. Surprisingly, CD4+ T cell lines from acutely and persistently EBV-infected donors consistently responded against EBV lytic cycle antigens and autoantigens, but barely against latent cycle antigens of EBV hitherto considered principal immunotherapeutic targets. Lytic cycle antigens were predominantly derived from structural proteins of the virus presented on MHC II via receptor-mediated uptake of released viral particles, but also included abundant infected cell proteins whose presentation involved intercellular protein transfer. Importantly, presentation of virion antigens was severely impaired by acyclovir treatment of stimulator cells, as currently performed in most clinical protocols.

CONCLUSIONS/SIGNIFICANCE

These results indicate that structural antigens of EBV are the immunodominant targets of CD4+ T cells in LCL-stimulated T cell preparations. These findings add to our understanding of the immune response against this human tumor-virus and have important implications for the improvement of immunotherapeutic strategies against EBV.

Use of CD107‐based cell sorting ex vivo to enrich subdominant CD8 + T cells in culture

CD8+ T lymphocytes are key effectors in the control of viral diseases and some tumours. In general, the majority of CD8+ T cells recognize a few immunodominant epitopes, but in some circumstances, subdominant specificities may be more relevant as targets for vaccines or immunotherapy. Epstein-Barr virus (EBV)-associated cancers are an example where knowledge of subdominant-specific CD8+ T cells is important because the immunodominant EBV proteins are not expressed in these cancers. We have developed a live-cell sorting method based on CD107 detection to remove CD8+ T cells recognising dominant EBV epitopes and show that this allows enrichment of subdominant-specific CD8+ T cells in subsequent cultures. This work shows that immunodomination in vitro suppresses the outgrowth of subdominant-specific CD8+ T cells in culture. The method may have broad applications for finding subdominant targets for immunotherapy and vaccines, and the principle suggests a means of improving subdominant CD8+ T-cell cultures grown for immunotherapy.

Associations among Epstein-Barr virus subtypes, human leukocyte antigen class I alleles, and the development of posttransplantation lymphoproliferative disorder in bone marrow transplant recipients

The association between Epstein-Barr virus subtype, human leukocyte antigen class I alleles, and the development of posttransplantation lymphoproliferative disorder was examined in a group of 25 bone marrow transplant recipients. A highly statistically significant correlation was observed between the human leukocyte antigen B51 allele and development of posttransplantation lymphoproliferative disorder (P=.0016). This study provides, to our knowledge, the first evidence that the human leukocyte antigen B51 allele might predispose bone marrow transplant recipients to Epstein-Barr virus-associated posttransplantation lymphoproliferative disorder.

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Post-transplant lymphoproliferative disorders (PTLD) after solid organ transplantation

Post-transplant lymphoproliferative disorders (PTLD) are a well-recognised and potentially fatal complication after solid organ transplantation. They include a spectrum of disorders ranging from benign hyperplasia to invasive malignant lymphoma. The majority of cases are associated with Epstein Barr virus (EBV)-driven tumour formation in B cells and are a consequence of the detrimental effect of immunosuppressive agents on the immune-control of EBV. This review provides an update on the pathogenesis and clinical features of PTLD after solid organ transplantation and discusses recent progress in management. Reduction in immunosuppressive therapy remains a key component of therapy for EBV-positive PTLD and may lead to remission in early disease. Chemotherapy is used when reduced immunosuppression fails to control early disease and as initial therapy for many cases of late disease. Unfortunately, the mortality for PTLD that fails to respond to a reduction in immunosuppression remains high. Newer treatments include manipulation of the cytokine environment, B lymphocyte depleting antibodies and adoptive T cell immunotherapy using allogeneic or autologous EBV-specific cytotoxic T lymphocytes. Although early results appear promising, well-designed clinical trials are needed to assess the efficacy of these novel approaches. EBV vaccination may in the future prove an effective prophylaxis against EBV-driven PTLD but until then, avoiding excessive immunosuppressive therapy may help minimise the risk of PTLD.

Post-transplant lymphoproliferative disorder of the cervix

BACKGROUND

Post-transplant lymphoproliferative disorder involving the female genital tract is a rare event.

CASE

A 67-year-old female status post orthotopic liver transplant 5 years previously for hepatitis B and sarcoidosis presented with vaginal bleeding. Endometrial biopsy revealed a high-grade malignant tumor with immunologic marker studies consistent with lymphoma. The patient underwent an exploratory laparotomy, modified radical hysterectomy, bilateral salpingo oophorectomy, bilateral selective pelvic and para-aortic lymphadenectomy, and omentectomy. Final pathology confirmed monomorphic B-cell post-transplantation lymphoproliferative disorder consistent with non-Hodgkin's B cell lymphoma confined to the endocervix and lower uterine segment. She remains recurrence free after 4 years with no adjuvant therapy.

CONCLUSION

Post-transplant complications can present in the female reproductive organs. Gynecologic oncologists need to be aware of this disease process when treating patients for gynecologic symptoms after transplant surgery.

Therapy of other viral infections: herpes to hepatitis

Over the past several years, there has been an increase in knowledge pertaining to the diagnosis and management strategies for the herpes family (Types 1-8), the pox viruses, mumps, measles, rubella, and parvovirus B19 as well as the viral etiologies of hepatitis. Various antiviral treatments, such as nucleoside analogs and interferon therapy, have been available to reduce the signs and symptoms of these common viral infections. This article summarizes the preferred treatment strategies to be employed for each of the viruses for reducing severity, duration, recurrences (notably in the herpes family), transmission rates, as well as preventive alternatives. The majority of the therapeutic options attenuate the course of disease. Treatment decisions are driven by knowledge of the natural history and often are tailored to incorporate clinical circumstances for individual patients. Promotion of community awareness and the development of vaccines should be emphasized in the battle against these common viruses, particularly the herpes simplex viruses, the pox viruses, and hepatitis B.

Lack of association of polyomavirus and herpesvirus types 6 and 7 in human lymphomas

BACKGROUND

The association of viruses with several human tumors has been studied for almost 100 years, and it remains a very controversial issue. Due to the fact that the presence of polyomaviruses and herpes viruses reportedly are associated with lymphomas, albeit with striking results and differences between the many studies, the authors undertook a study into the presence of viral sequences of polyomavirus (BK virus, JC virus, and especially simian virus 40 [SV40]) in human lymphomas in an attempt to explain this contradictory association. To complete the study, the presence of different virus types from the herpesviriridae family were analyzed, such as herpesvirus type 6 (HHV6), HHV7, HHV8, and Epstein-Barr virus, in human lymphomas.

METHODS

DNA was isolated from 83 frozen human lymphoma samples, and different polymerase chain reaction techniques were used to find polyomavirus and herpesvirus sequences in these samples. To assess the incidence of the presence of sequences in lymphomas, a parallel analysis was made of 53 samples from normal donor spleen lymphocytes. Positive samples were analyzed for polyomavirus sequences by immunohistochemistry.

RESULTS

Polyomavirus sequences were detected in 9 of 83 lymphomas (11%), and SV40 sequences could be confirmed in only 1 lymphoma. Immunohistochemistry for large-T antigen was negative in all samples. Herpesviruses were detected in 53 of 83 lymphomas (63.9%), were detected more frequently in Hodgkin lymphomas (80%) than in non-Hodgkin lymphomas (58.7%), and were detected in > 60% of normal spleen lymphocytes.

CONCLUSIONS

The current results did not support a clear association of polyomavirus and HHV6 or HHV7 with lymphomas; HHV6 and HHV7 sequences were detected in a similar percentage of normal samples and lymphomas. The lack of significant differences between normal and malignant lymphocytes and the absence of viral protein expression in the tumor cells did not allow the establishment of a clinical correlation between polyomaviruses or HHVs (HHV6, HHV7, HHV8) and lymphomas. Nevertheless, because viral products can be lost during tumor progression, and because host factors can modulate the oncogenic role of some viruses, the hypothetical role of these viruses cannot be discarded completely.