Hodgkin's disease and anaplastic large cell lymphoma revisited

In cultures, and in tissues as well, Hodgkin's and Reed-Sternberg (H-RS) cells and anaplastic large cell lymphoma (ALCL) cells are known to express a variety of cytokines, including IL-1, -5, -6, -8, -9, TNF-, GM-CSF, M-CSF, TGF-, CD70, CD80, and CD86. Various numbers of H-RS/ALCL cells may express cytokine receptors (R), such as CD30, CD40, IL-2R (CD25/CD122), IL-6R (CD126), IL-7R (CD127), TNF-R (CD120), TGF--R (CD105/endoglin), M-CSF-R (CD115), and SCF-R (CD117/c-kit receptor). All of these cytokines and cytokine receptors are implicated in the growth regulation of H-RS/ALCL cells, the histopathologic alterations in tissues, and the clinical manifestations in patients with Hodgkin's disease (HD) or ALCL. Many of these cytokines or cytokine receptors also play an important role in the pathogenesis of other types of lymphomas. In this review, we describe the cytokine or cytokine-receptor expression that is diacritic for H-RS/ALCL cells. The identification of such unique cytokine-cytokine receptor interactions is likely to explain the biologic property that distinguishes HD/ALCL from other types of lymphomas. These interactions include those of CD30L-CD30, CD40L-CD40, CD70-CD27, CD80/CD86-CD28, SCF-CD117, IL-9-IL9R, and IL-7-IL-7R. The H-RS/ALCL cells express IL-9 and two cytokine receptors, CD30 and CD117, which are observed infrequently in NHLs. Although IL-7 expression is not restricted to H-RS/ALCL cells, the expression of IL-7 in conjunction with IL-9 and/or CD117 may be regarded as unique for HD/ALCL because of an unusual combination and a synergistic activity among these cytokines. The expression of CD70 and CD80/CD86 (as cytokines) may exert a unique effect in HD because of intimate contact between H-RS cells and CD27/CD28-positive T cells. The expression of these costimulators (CD70 and CD80/CD86) and other adhesion/constimulator molecules such as CD54 and CD58, along with the secretion of soluble cytokines such as Il-1, IL-6, IL-7, or TNFs by H-RS/ALCL cells, could result in the profound T-cell proliferation often seen in lymph nodes involved by HD and some ALCL. On the other hand, the expression of CD30L and CD40L by surrounding T cells may affect the proliferation of H-RS/ALCL cells. The cytokine-cytokine receptor interaction between H-RS cells and T cells via direct cell-cell contact is bidirectional, a situation not commonly seen in NHLs.     

Hodgkin's disease derived cell lines: a review.

A number of so-called "HD cell lines" have been established over the last 10-15 years (Table 1). Or those 15 cell lines we studied, only the cell lines CO, DEV, HD-70, HDLM, KM-H2, L-428, L-540 and SUP-HD1 can be regarded to represent true HD cell lines. According to the immunostaining results and molecular genetic data, these 8 cell lines can be assigned either to the T-cell lineage (CO, HDLM, L-540) or B-cell lineage (DEV, HD-70, KM-H2, SUP-HD1). With the data currently available, the cell lineage origin of L-428 cannot be unequivocally determined, but appears to be lymphoid. All but one of these eight HD cell lines have been established from patients with the nodular sclerosis subtype. Therefore, the conclusions drawn from the in vitro studies are limited to this histological subtype of HD. It is conceivable that culture conditions select for a particular type of cell that will survive. The state of differentiation of these HD cell lines remains unclear due to the incomplete expression of T- or B-cell antigens. The in vitro cells and the in vivo H-RS cells share, however, the expression of the unique activation markers CD15, CD25, CD30, CD71 and HLA-DR. Recently published data indicate that the HD cell lines express and produce a large number of cytokines. Multiple non-random chromosomal abnormalities and the expression of various proto-oncogenes are also new and exciting findings and certainly deserve further study. In summary, although the cultured cells are not unequivocally proven to be the direct progeny of in vivo H-RS cells, several continuous HD cell lines have been established that display a variety of phenotypical features identical or similar to those of their presumed in vivo counterparts. Surface marker, molecular genetic and other features suggest a T- or B-cell derivation. An extrapolation of these conclusions would point to a lymphoid origin of H-RS cells. Whether H-RS cells can originate from other cell types such as monocytes/macrophages or reticulum cells, cannot be answered with the currently available HD cell lines.     

Hodgkin’s disease: A disorder of dysregulated cellular cross-talk

Hodgkin’s disease (HD) is a peculiar type of human malignant lymphoma characterized by a very low frequency of tumor cells, the so called Hodgkin and Reed-Sternberg (H-RS) cells, embedded in a hyperplastic background of non-neoplastic (reactive) cells recruited and activated by H-RS cells-derived cytokines. H-RS cells can be functionally regarded as antigen-presenting cells (APC) able to elicit an intense, but anergic and ineffective, T-cell mediated immune response along with a hyperplastic inflammatory reaction which involves several cell types including T- and B-cells, neutrophils, eosinophils, plasma cells, fibroblasts and stromal cells. In tissues involved by HD, malignant H-RS cells and their reactive neighboring cells are able to cross-talk via a complex network of cytokine- and cell contact-dependent interactions. As a result of such interactions, mediated by specific surface receptors and adhesion molecules on both tumor and non-neoplastic cells, H-RS cells may receive several proliferative and anti-apoptotic signals favoring the cellular expansion and tumor cell survival in HD. The ineffective T-cell immune response elicited by the abnormal APC function of H-RS cells may further contribute to the biologic and clinical progression of HD. Innovative therapeutic strategies aimed at blocking the pathways of dysregulated cellular cross-talk among H-RS cells and bystander reactive cell populations might be beneficial in the treatment of HD patients. Supported by the Associazione Italiana per la Ricerca sul Cancro; the Associazione Italiana contro le Leucemie, ‘Trenta ore per la vita’ and the Ministero della Sanità, Ricerca Finalizzata I.R.C.C.S., Italy.     

Cytomorphologic differentiation of Hodgkin's lymphoma and Ki-1+ anaplastic large cell lymphoma in fine needle aspirates

OBJECTIVE: To cytomorphologically differentiate Hodgkin's lymphoma (HL) from Ki-1+ anaplastic large cell lymphoma (ALCL) in fine needle aspirates. STUDY DESIGN: We blindly reviewed 63 fine needle aspiration (FNA) smears from histologically and immunophenotypically proven cases of ALCL (n = 15) and HL (n = 48). The smears were reviewed for the following criteria: (1) estimated percentages of abnormal cells, (2) pattern of the smears (polymorphous vs. dimorphous), and (3) presence or absence of multilobated cells. RESULTS: All cases were phenotyped by immunohistochemistry for CD3, CD15, CD20, CD30 and CD45, with flow cytometric immunophenotpyping in 41 cases. Flow cytometric phenotyping was not successful in any of the cases. The smears were polymorphous in all 15 cases of ALCL and in 1 case of HL (2%). The percentage of abnormal cells ranged from 10% to 90% in cases of ALCL (median, 30%) whereas it ranged from 1% to 25% in HL (median 3%; P = .0003). Three cases of HL showed abnormal cells constituting > or = 20% of the smears. They were all grade 2 disease. Multilobated cells were identified in 14 of the 15 cases of ALCL (93%) and in 3 of the 48 cases of HL (6.25%; P = .0008). CONCLUSION: Our findings indicate that the differentiation of ALCL from HL can be achieved in FNA smears through identification of abnormal cells representing > 30% of the population, a spectrum of abnormal cells and the presence of multilobated nuclei. Rare cases of grade 2 HL may be difficult to differentiate from ALCL.     

HD39 (B3), a B lineage-restricted antigen whose cell surface expression is limited to resting and activated human B lymphocytes

The B cell-restricted antigen HD39, whose cell surface expression is limited to resting and activated human B lymphocytes, is described in this report. The monoclonal antibody HD39 detects a two-chain glycoprotein with apparent molecular weights of 130,000 and 140,000. During B cell ontogeny, HD39 is first expressed in the cytoplasm of bone marrow derived pre-B cells, then appears on the cell surface of sIgM+ B cells, and finally on the majority of sIgM+ sIgD+ resting B cells. After activation in vitro, the expression of HD39 on the cell surface first increases, and then the antigen is lost as cells begin to differentiate. HD39 is weakly expressed on very few non-T cell ALL and B cell CLL, on approximately 50% of B cell lymphomas, and not on Waldenstr?m's macroglobulinemias and myelomas. In contrast, it is strongly expressed on all hairy cell leukemias. Its limited cell surface expression in B cell ontogeny suggests that HD39 may be important in the events that regulate the activation of the human resting B lymphocytes.     

Anaplastic large cell lymphoma presenting as a pleural effusion and mimicking primary effusion lymphoma. A report of 2 cases

BACKGROUND: Systemic anaplastic large cell lymphoma (ALCL) is predominantly a nodal disease, but extranodal involvement can occur during the disease course or as the primary presentation. We report two rare cases of ALCL presenting with a pleural effusion, mimicking primary effusion lymphoma (PEL). CASES: Two patients, a 47-year-old woman and an 81-year-old man, presented with a pleural effusion for investigation. The pleural fluid contained abundant, large, lymphoid cells with marked nuclear atypia. These neoplastic cells strongly expressed CD30 and EMA and showed a T-cell phenotype (CD3+CD45RO+ for case 1 and CD4+ for case 2). Case 1, in addition, showed ALK1 expression. The tumor cells in both cases were negative for human herpes virus type 8 (HHV8) and Epstein-Barr virus (EBV). ALCL shows overlapping cytologic features with PEL, but the T-cell phenotype, ALK1 expression in case 1, lack of association with HHV8 and EBV, HIV seronegativity and subsequent discovery of nodal disease in case 2 were all in favor of ALCL over PEL. CONCLUSION: In rare cases a pleural effusion is the presenting feature of ALCL, and distinction from PEL depends on correlation with clinical findings, detailed immunophenotyping and study of the status of HHV8 and EBV.     

Epstein-Barr virus (EBV) and human disease: facts, opinions and problems

The human herpesvirus, Epstein-Barr virus (EBV), has classically been associated with two pathologies with frequencies approaching 100%. One of these, Burkitt's lymphoma (BL), is of B-cell origin and the other, nasopharyngeal carcinoma (NPC), is a tumour of poorly differentiated epithelial cells. More recently, EBV had been identified with frequencies from a few percent to 100% (in one case) with a variety of other malignancies. These include Hodgkin's disease (HD; where in the west, the frequency of association is about 50%), sino-nasal T-cell lymphomas, lymphoepitheliomas, some sarcomas and breast cancers, other cancers from the head and neck, and lymphomas arising in patients with immune dysfunctions. Since EBV is ubiquitous, with the vast majority of the world's population having met and seroconverted to the virus, the diversity of tumours with which it has now been associated represents a substantial health burden. In a recent IARC monograph, EBV was classified as a group 1 carcinogen. Here, the data on BL and NPC, as they relate to geographical restrictions, viral strain variation, co-factors in disease, and genetic components are reexamined. We raise the question whether in their origins, these tumours genuinely reflect distinct and independent events, as deemed at present, or may represent a response by different cell types to common extracellular factors. For example, a situation in Kenya apparently existed in the past, where both BL and NPC were observed in ethnic Africans with roughly equal frequencies; more recently, in Kenya, EBV has been identified in nearly 100% of the tumours in children with HD. We also consider tumours where the viral association is reportedly of low frequency, and offer explanations for these data, including the possibility of loss of the viral genome once malignancy has been initiated. If this phenomenon occurs as a frequent secondary event, EBV could be an even greater health risk than presently believed.     

Endothelial dysfunction in the early- and late-stage type-2 diabetic Goto-Kakizaki rat aorta

Hodgkin and Reed-Sternberg (H-RS) cells of classical Hodgkin lymphoma (cHL) present an impaired expression of immunoglobulin genes, but escape apoptotic death. We investigated whether nitric oxide synthases (NOS) are expressed by H-RS cells, studied their association with EBV status and the expression of apoptotic proteins, and investigated their relationship to the clinical outcome of 171 patients. NOS1 and NOS2 were expressed in a large number of cases, whereas NOS3 expression was not detected. Positive associations were found between NOS1 and p53, bax and NOS2, bcl-2 and NOS2, bax and p53, and between bax and fasL. Inverse correlations were established between EBV and NOS2 and between EBV and bcl-2. A shorter overall survival (OS) was associated with strong expression of NOS2. In conclusion, NOS are expressed by H-RS cells of cHL.     

Human embryonal epithelial cells of the developing small intestinal crypts can express the Hodgkin-cell associated antigen Ki-1 (CD30) in spontaneous abortions during the first trimester of gestation

Background  

Ki-1 (CD30) antigen expression is not found on peripheral blood cells but its expression can be induced in vitro on T and B lymphocytes by viruses and lectins. Expression of CD30 in normal tissues is very limited, being restricted mainly to a subpopulation of large lymphoid cells; in particular, cells of the recently described anaplastic large cell lymphoma (ALCL), the Reed-Sternberg (RS) cells of Hodgkin's lymphoma and scattered large parafollicular cells in normal lymphoid tissues. More recent reports have described CD30 expression in non-hematopoietic and malignant cells such as cultured human macrophages, human decidual cells, histiocytic neoplastic cells, mesothelioma cells, embryonal carcinoma and seminoma cells.     

Involvement of Cot activity in the proliferation of ALCL lymphoma cells

Anaplastic large-cell lymphoma (ALCL) cells overexpress CD30 on their cell surface, show increased levels of activated Erk1/2 and of JunB; participating JunB in the proliferative capacity of these lymphomas. Here, we show that ALCL lymphoma cells also present high expression levels of the proto-oncogenic Cot (MAP3K8). Using pharmacological drugs as well as the RNA interference technique we show that Cot protein is responsible for the constitutive Erk1/2 activation in the ALCL lymphoma cells, SUDHL-1. Besides, inhibition of Cot activity reduces the number of cell divisions which is achieved, at least in part, by the control that Cot exercises on the activation state of p70 S6K and on the expression levels of JunB. Since Cot represents an alternative mode, independently of RAF, to activate Erk1/2, all these data strongly suggest that molecular targeting of Cot may be a potential new specific strategy for ALCL lymphomas therapy, without the fully disturbance of the Erk1/2 function.     

Peripheral T-cell lymphoma or Hodgkin's disease in a HIV seropositive patient: a histopathological study

Malignant lymphomas occurring in patients with AIDS are usually derived from the B-cell lineage while T-cell malignant lymphomas are very rare in these patients. We report a HIV seropositive 29-year-old homosexual man in whom cervical lymph node biopsy showed an atypical lymphoproliferative process. On morphological and paraffin section immunohistochemical grounds the possibility of Hodgkin's disease (HD) mixed cellularity was initially suggested, but frozen section immunohistochemical studies revealed that the cellular infiltrate exhibited an aberrant pan T immunophenotype and consequently the diagnosis of peripheral T-malignant lymphomas (T-ML) was made. However, genotypic studies would be required to definitely confirm this diagnosis, in such cases. In our case, varying numbers of small and medium-sized cells were positive for both Leu 3/CD4 and Leu 2/CD8 whereas some large cells reacted only with Leu 3/CD4 antibody. Some medium-sized, large and giant cells showed cytoplasmic positivity for Leu M1/CD15. Furthermore, the positivity of many large and giant cells with the activation markers BerH2/CD30, Ki-1/CD30, Tac/CD25 and HLA-DR suggested an activation state for these cells. Our findings emphasize the usefulness of frozen section immunohistochemical methods in order to investigate the spectrum of lymphoid malignancies occurring in HIV seropositive patients, and confirm results of previous studies which stressed the diagnostic difficulties that may appear in distinguishing HD from peripheral T-ML.     

Hodgkin's cell lectin, a lymphocyte adhesion molecule and mitogen

We have previously shown a novel galactose/N-acetylgalactosamine specific lectin activity (Hodgkin's disease (HD) lectin) on the surface of cultured HD cells (lines L428, its variants, and line L540) to mediate lymphocyte adhesion. We here demonstrate that both surface membrane-bound and secreted HD lectin activities participate in the activation of agglutinated lymphocytes. Among known adhesion molecules expressed by the HD cells, only the intercellular adhesion molecule-1 (ICAM-1) contributed to this activation as an alternative PBL binding site. As yet we have not identified the cellular ligand(s) for the HD lectin on the lymphocyte surface. Pretreatment of lymphocytes with mAb to the accessory molecules CD2, CD3, CD4, CD8, CD11b, or CD11c did not interfere with their response to HD cells. mAb to CD11a (LFA-1), the alleged ligand of ICAM-1, inhibited the ICAM-1 but not the HD lectin-mediated lymphocyte stimulation. Although lymphocyte binding could proceed via either pathway, lymphocyte activation always depended upon factors secreted by the HD cells, one of which we identified as a soluble form of the HD lectin based on its shared properties with the membrane-bound form including immunologic cross-recognition and carbohydrate-binding specificity. Although HD cell-conditioned medium alone stimulated lymphocytes, HD cell plasma membranes could compensate for low concentrations of this medium. In addition, resting lymphocytes, normally unresponsive, were triggered into DNA synthesis by growth medium when cocultured with HD cell membranes. The unique functions of the surface-expressed HD lectin and its soluble counterpart as lymphocyte adhesion molecule and mitogen might be physiologically relevant to the severe immunodeficiencies occurring in patients with HD.     

Common germinal-center B-cell origin of the malignant cells in two composite lymphomas, involving classical Hodgkin's disease and either follicular lymphoma or B-CLL

BACKGROUND: Classical Hodgkin's disease (HD) and B-cell non-Hodgkin lymphoma (NHL) occasionally occur in the same patient. Such composite lymphomas represent interesting models to study the pathogenesis of B-cell lymphomas and the relationship between HD and B-cell NHL. MATERIALS AND METHODS: We analyzed two composite lymphomas (a combination of classical HD with follicular lymphoma [FL] and a combination of classical HD with B-cell chronic lymphocytic leukemia [B-CLL]) by micromanipulation of single cells from tissue sections and amplification of immunoglobulin V region genes for the clonal relationship of the tumor cells. RESULTS: In both cases, clonally related variable (V) genes with both shared as well as distinct somatic mutations were obtained from the two lymphomas, showing that in each of the cases the distinct tumor cells were members of a common germinal center (GC) B-cell clone. FL cells from two different lymph nodes of patient 1 showed a similar mutation pattern, suggesting that infiltration of these lymph nodes by tumor cells was not restricted to a particular FL cell or subclone. In the FL, a single cell was identified with a mutation signature indicating that premalignant cells can persist in the tissue. CONCLUSIONS: The cases presented here further underline the close relationship between HD and B-cell NHL and the role of the GC in lymphomagenesis. Whereas the latter was already suggested for FL and HD, the present study indicates that also in the B-CLL subset characterized by mutated Ig genes, important steps in malignant transformation happen in the GC, and that HRS cells can derive from CD5-positive B cells.     

Reed-Sternberg cells and "bystander" lymphocytes in lymph nodes affected by Hodgkin's disease are infected with different strains of Epstein-Barr virus.

In most cases of Epstein-Barr virus (EBV)-associated Hodgkin's disease (HD), EBV-positive Reed-Sternberg (RS) cells and rare EBV-positive reservoir lymphocytes coexist in lymph nodes. Here we show that, in two cases of EBV-associated HD, strains infecting RS cells and reservoir lymphocytes of the same patient have different BNLF-1 genes. This suggests that RS cells and reservoir lymphocytes of the same patient are infected by different EBV strains.     

Epstein-Barr virus-associated lymphoproliferative disorders

Epstein-Barr virus (EBV) is a ubiquitous member of the herpesvirus family that is associated with a variety of lymphomas and lymphoproliferative diseases. It encodes a multitude of genes that drive proliferation or confer resistance to cell death. Among these are two key viral proteins which mimic the effects of the activated cellular signaling proteins. EBV-associated lymphomas include Burkitt's lymphoma; natural killer (NK)/T-cell lymphoma, lymphoma and lymphoproliferative diseases in immunocompromized populations, and Hodgkin's lymphoma. The character of the viral association differs among these entities with some consistently associated with EBV in all populations and all parts of the world, and others associated with the virus only in particular circumstances. An example of the former is nasal NK/T-cell lymphoma, while an example of the latter is Burkitt's lymphoma. The pattern of viral gene expression also varies among tumor types with different viral genes playing key roles in different tumors and conferring sensitivity to immune surveillance. Thus some of the post-transplant lymphoproliferative diseases are exquisitely sensitive to CD8 T-cell immunosurveillance, while other tumors such as Burkitt's lymphoma may be nearly impervious to such surveillance. Knowledge of the EBV association is not only important for understanding the pathogenesis of these tumors, but is increasingly important for diagnosis, monitoring and treatment.     

Tyrosine phosphorylation in human lymphomas

In a previous study, we showed that the high level of protein tyrosine phosphorylation present in lymphomas containing an anaplastic lymphoma kinase (ALK) can be demonstrated in routinely processed paraffin tissue sections using immunolabelling techniques. In the present study we investigated whether oncogenic tyrosine kinase activation also occurs in other categories of lymphoma by staining 145 cases of lymphoma covering those tumours with a range of different subtypes including those with morphological similarity to ALK-positive anaplastic large cell lymphoma (ALCL). Twelve cases of the borderline malignant disorder lymphomatoid papulosis were also studied. Twenty seven of the 28 cases of ALK-positive ALCL showed the extensive cytoplasmic labelling for phosphotyrosine in the neoplastic cells. The remaining case containing moesin-ALK exhibited membrane-associated phosphotyrosine expression. There was no nuclear phosphotyrosine labelling in any of the ALK-positive ALCL, even though ALK was present within the cell nuclei in 23 of the tumours. Variable degrees of phosphotyrosine labelling, usually membrane-restricted, were observed in 7/40 cases of ALK-negative ALCL, 9/29 cases of diffuse large B-cell lymphoma, 3/6 cases of mediastinal B-cell lymphoma, 2/7 cases of Hodgkin's lymphoma, 3/6 cases of peripheral T-cell lymphomas unspecified, 4/6 cases of B-cell chronic lymphocytic leukaemia, 2/6 cases of follicular lymphomas and 2/12 cases of lymphomatoid papulosis studied. However none of these phosphotyrosine-positive cases showed the strong cytoplasmic labelling comparable to that seen in ALK-positive lymphoma. We conclude that activation of a tyrosine kinase is probably not a major oncogenic event in lymphomas other than ALK-positive ALCL.     

Correlation between the expression of CD4 and the level of CD4 mRNA in human B-cell lines

Lines of Epstein-Barr virus (EBV)-transformed lymphoblastoid B-cells (B-LCLs) differ in the expression of surface CD4 glycoproteins. The aim of the present study was to correlate the expression of CD4 molecules on B-LCL cells with the synthesis of CD4 mRNA. RT-PCR assays were performed with oligonucleotide primers designed to detect mRNA corresponding to intracellular, transmembrane, or extracellular portions of the CD4 molecule. RT-PCR assays with all sets of primers were positive in T-cell populations, but were negative in various B-cell lymphoma lines. The majority of the LCLs established by EBV transfection of non-selected B-cells yielded positive results with at least some of the primer sets used for detection of CD4 mRNA. A significant positive correlation was found between the proportion of CD4+ cells in various B-LCLs and the concentration of CD4 mRNA. LCLs established from B-cells which synthesized various antibodies did not express CD4 molecules and either failed to synthesize CD4 mRNA or produced very low concentrations. These findings indicate that the expression of CD4 on B-LCLs is directly correlated with the concentration of CD4 mRNA synthesized and with the differentiation stage in which B-cells were immortalized by EBV infection.     

Interferon regulatory factor 7 is associated with Epstein-Barr virus-transformed central nervous system lymphoma and has oncogenic properties

Interferon regulatory factor 7 (IRF-7) is implicated in the regulation of Epstein-Barr virus (EBV) latency. EBV transforms primary B cells, and the major EBV oncoprotein, latent membrane protein 1 (LMP-1), is required for the process. LMP-1 both induces the expression of IRF-7 and activates the IRF-7 protein by phosphorylation and nuclear translocation. Here we report that the expression of IRF-7 is increased in EBV-immortalized B lymphocytes compared with that in primary B cells. IRF-7 was phosphorylated and predominantly localized in the nucleus in the immortalized cells. The expression of IRF-7 was detected in 19 of 27 specimens of primary lymphomas of the human central nervous system by immunohistochemical analysis. The association between LMP-1 and IRF-7 was statistically highly significant for these specimens. An appreciable amount of the IRF-7 expressed in lymphoma cells was localized in the nucleus. Furthermore, IRF-7 promoted the anchorage-independent growth of NIH 3T3 cells. LMP-1 and IRF-7 showed additive effects on the growth transformation of NIH 3T3 cells. IRF-7-expressing NIH 3T3 cells formed tumors in athymic mice. Thus, IRF-7 has oncogenic properties and, along with LMP-1, may mediate or potentiate the EBV transformation process in the pathogenesis of EBV-associated lymphomas.     

Increased CD8+ T Cell Response to Epstein-Barr Virus Lytic Antigens in the Active Phase of Multiple Sclerosis

It has long been known that multiple sclerosis (MS) is associated with an increased Epstein-Barr virus (EBV) seroprevalence and high immune reactivity to EBV and that infectious mononucleosis increases MS risk. This evidence led to postulate that EBV infection plays a role in MS etiopathogenesis, although the mechanisms are debated. This study was designed to assess the prevalence and magnitude of CD8+ T-cell responses to EBV latent (EBNA-3A, LMP-2A) and lytic (BZLF-1, BMLF-1) antigens in relapsing-remitting MS patients (n = 113) and healthy donors (HD) (n = 43) and to investigate whether the EBV-specific CD8+ T cell response correlates with disease activity, as defined by clinical evaluation and gadolinium-enhanced magnetic resonance imaging. Using HLA class I pentamers, lytic antigen-specific CD8+ T cell responses were detected in fewer untreated inactive MS patients than in active MS patients and HD while the frequency of CD8+ T cells specific for EBV lytic and latent antigens was higher in active and inactive MS patients, respectively. In contrast, the CD8+ T cell response to cytomegalovirus did not differ between HD and MS patients, irrespective of the disease phase. Marked differences in the prevalence of EBV-specific CD8+ T cell responses were observed in patients treated with interferon-β and natalizumab, two licensed drugs for relapsing-remitting MS. Longitudinal studies revealed expansion of CD8+ T cells specific for EBV lytic antigens during active disease in untreated MS patients but not in relapse-free, natalizumab-treated patients. Analysis of post-mortem MS brain samples showed expression of the EBV lytic protein BZLF-1 and interactions between cytotoxic CD8+ T cells and EBV lytically infected plasma cells in inflammatory white matter lesions and meninges. We therefore propose that inability to control EBV infection during inactive MS could set the stage for intracerebral viral reactivation and disease relapse.