The impact of HLA class I and EBV latency-II antigen-specific CD8(+) T cells on the pathogenesis of EBV(+) Hodgkin lymphoma

Classic Hodgkin lymphoma: Pathobiological features that impact emerging therapies

Classic Hodgkin lymphoma (cHL) is defined by distinctive Hodgkin Reed-Sternberg (HRS) cells, which are CD30+/CD15+ multinucleated tumor cells lacking typical B-cell markers. These cells comprise <5 % of tumor mass but orchestrate an extensive immunosuppressive tumor microenvironment (TME). Classic HL was curable with radiation therapy and multi-agent chemotherapy. Despite high cure rates, treatment-related toxicities remain significant. The goals of multimodality therapy are to achieve a cure while minimizing treatment-associated toxicity. Advances in molecular insights into HRS cells have led to transformative therapies, including checkpoint inhibitors, antibody-drug conjugates like brentuximab vedotin, which have shown remarkable efficacy, especially in relapsed or refractory disease. However, challenges persist due to the heterogeneity of cHL, driven by the complex biology of HRS cells and their surrounding tumor microenvironment. Novel approaches such as single-cell RNA sequencing and circulating tumor DNA profiling provide promising strategies to address these challenges. This review examines the origin, morphology, phenotype, and genetic profiles of HRS cells, highlighting key pathobiological features, including biomarkers and Epstein-Barr Virus involvement. It also explores the biological mechanisms underlying HRS cell survival and evaluates standard and emerging therapies, offering insights into the rationale for novel treatment strategies.

Genetics of immune response to Epstein-Barr virus: prospects for multiple sclerosis pathogenesis

Epstein-Barr virus (EBV) infection has been advocated as a prerequisite for developing multiple sclerosis (MS) and possibly the propagation of the disease. However, the precise mechanisms for such influences are still unclear. A large-scale study investigating the host genetics of EBV serology and related clinical manifestations, such as infectious mononucleosis (IM), may help us better understand the role of EBV in MS pathogenesis. This study evaluates the host genetic factors that influence serological response against EBV and history of IM and cross-evaluates them with MS risk and genetic susceptibility in the Swedish population. Plasma IgG antibody levels against EBV nuclear antigen-1 [EBNA-1, truncated = amino acids (aa) (325-641), peptide = aa(385-420)] and viral capsid antigen p18 (VCAp18) were measured using bead-based multiplex serology for 8744 MS cases and 7229 population-matched control subjects. The MS risk association for high/low EBV antibody levels and history of IM was compared to relevant clinical measures along with sex, age at sampling, and associated HLA allele variants. Genome-wide and HLA allele association analyses were also performed to identify genetic risk factors for EBV antibody response and IM history. Higher antibody levels against VCAp18 [odds ratio (OR) = 1.74, 95% confidence interval (CI) = 1.60-1.88] and EBNA-1, particularly the peptide (OR = 3.13, 95% CI = 2.93-3.35), were associated with an increased risk for MS. The risk increased with higher anti-EBNA-1 IgG levels up to 12× the reference risk. We also identified several independent HLA haplotypes associated with EBV serology overlapping with known MS risk alleles (e.g. DRB1*15:01). Although there were several candidates, no variants outside the HLA region reached genome-wide significance. Cumulative HLA risk for anti-EBNA-1 IgG levels, particularly the peptide fragment, was strongly associated with MS. In contrast, the genetic risk for high anti-VCAp18 IgG levels was not as strongly associated with MS risk. IM history was not associated with class II HLA genes but negatively associated with A*02:01, which is protective against MS. Our findings emphasize that the risk association between anti-EBNA-1 IgG levels and MS may be partly due to overlapping HLA associations. Additionally, the increasing MS risk with increasing anti-EBNA-1 levels would be consistent with a pathogenic role of the EBNA-1 immune response, perhaps through molecular mimicry. Given that high anti-EBNA-1 antibodies may reflect a poorly controlled T-cell defence against the virus, our findings would be consistent with DRB1*15:01 being a poor class II antigen in the immune defence against EBV. Last, the difference in genetic control of IM supports the independent roles of EBNA-1 and IM in MS susceptibility.

Geographic EBV variants confound disease-specific variant interpretation and predict variable immune therapy responses

ABSTRACT

Epstein-Barr virus (EBV) is a potent carcinogen linked to hematologic and solid malignancies and causes significant global morbidity and mortality. Therapy using allogeneic EBV-specific lymphocytes shows promise in certain populations, but the impact of EBV genome variation on these strategies remains unexplored. To address this, we sequenced 217 EBV genomes, including hematologic malignancies from Guatemala, Peru, Malawi, and Taiwan, and analyzed them alongside 1307 publicly available EBV genomes from cancer, nonmalignant diseases, and healthy individuals across Africa, Asia, Europe, North America, and South America. These included, to our knowledge, the first natural killer (NK)/T-cell lymphoma (NKTCL) EBV genomes reported outside of East Asia. Our findings indicate that previously proposed EBV genome variants specific to certain cancer types are more closely tied to geographic origin than to cancer histology. This included variants previously reported to be specific to NKTCL but were prevalent in EBV genomes from other cancer types and healthy individuals in East Asia. After controlling for geographic region, we did identify multiple NKTCL-specific variants associated with a 7.8-fold to 21.9-fold increased risk. We also observed frequent variations in EBV genomes that affected peptide sequences previously reported to bind common major histocompatibility complex alleles. Finally, we found several nonsynonymous variants spanning the coding sequences of current vaccine targets BALF4, BKRF2, BLLF1, BXLF2, BZLF1, and BZLF2. These results highlight the need to consider geographic variation in EBV genomes when devising strategies for exploiting adaptive immune responses against EBV-related cancers, ensuring greater global effectiveness and equity in prevention and treatment.

Epstein-Barr virus-associated lymphomas decoded

Epstein-Barr virus (EBV)-associated lymphomas cover a range of histological B- and T-cell non-Hodgkin and Hodgkin lymphoma subtypes. The role of EBV on B-cell malignant pathogenesis and its impact on the tumour microenvironment are intriguing but incompletely understood. Both the International Consensus Classification (ICC) and 5th Edition of the World Health Organization (WHO-HAEM5) proposals give prominence to the distinct clinical, prognostic, genetic and tumour microenvironmental features of EBV in lymphoproliferative disorders. There have been major advances in our biological understanding, in how to harness features of EBV and its host immune response for targeted therapy, and in using EBV as a method to monitor disease response. In this article, we showcase the latest developments and how they may be integrated to stimulate new and innovative approaches for further lines of investigation and therapy.

Hodgkin Lymphoma: A disease shaped by the tumor micro- and macroenvironment

The tumor microenvironment (TMicroE) and tumor macroenvironment (TMacroE) are defining features of classical Hodgkin lymphoma (cHL). They are of critical importance to clinicians since they explain the common signs and symptoms, allow us to classify these neoplasms, develop prognostic and predictive biomarkers, bioimaging and novel treatments. The TMicroE is defined by effects of cancer cells to their immediate surrounding and within the tumor. Effects of cancer cells at a distance or outside of the tumor define the TMacroE. Paraneoplastic syndromes are signs and symptoms due to effects of cancer at a distance or the TMacroE, which are not due to direct cancer cell infiltration. The most common paraneoplastic symptoms are B-symptoms, which manifest as fevers, chills, drenching night sweats, and/or weight loss. Less common paraneoplastic syndromes include those that affect the central nervous system, skin, kidney, and hematological autoimmune phenomena including hemophagocytic lymphohistiocytosis (HLH). Paraneoplastic signs such as leukocytosis, lymphopenia, anemia, and hypoalbuminemia are prognostic biomarkers. The neoplastic cells in cHL are the Hodgkin and Reed Sternberg (HRS) cells, which are preapoptotic germinal center B cells with a high mutational burden and almost universal genetic alterations at the 9p24.1 locus primarily through copy gain and amplification with strong activation of signaling via PD-L1, JAK-STAT, NFkB, and c-MYC. In the majority of cases of cHL over 95% of the tumor cells are non-neoplastic. In the TMicroE, HRS cells recruit and mold non-neoplastic cells vigorously via extracellular vesicles, chemokines, cytokines and growth factors such as CCL5, CCL17, IL6, and TGF-β to promote a feed-forward inflammatory loop, which drives cancer aggressiveness and anti-cancer immune evasion. Novel single cell profiling techniques provide critical information on the role in cHL of monocytes-macrophages, neutrophils, T helper, Tregs, cytotoxic CD8+ T cells, eosinophils, mast cells and fibroblasts. Here, we summarize the effects of EBV on the TMicroE and TMacroE. In addition, how the metabolism of the TMicroE of cHL affects bioimaging and contributes to cancer aggressiveness is reviewed. Finally, we discuss how the TMicroE is being leveraged for risk adapted treatment strategies based on bioimaging results and novel immune therapies. In sum, it is clear that we cannot effectively manage patients with cHL without understanding the TMicroE and TMacroE and its clinical importance is expected to continue to grow rapidly.

Classic Hodgkin lymphoma in young people

Classic Hodgkin lymphoma (CHL) is a unique form of lymphoid cancer featuring a heterogeneous tumor microenvironment and a relative paucity of malignant Hodgkin and Reed-Sternberg (HRS) cells with characteristic phenotype. Younger individuals (children, adolescents and young adults) are affected as often as the elderly, producing a peculiar bimodal age-incidence profile that has generated immense interest in this disease and its origins. Decades of epidemiological investigations have documented the populations most susceptible and identified multiple risk factors that can be broadly categorized as either biological or environmental in nature. Most risk factors result in overt immunodeficiency or confer more subtle alterations to baseline health, physiology or immune function. Epstein Barr virus, however, is both a risk factor and well-established driver of lymphomagenesis in a significant subset of cases. Epigenetic changes, along with the accumulation of somatic driver mutations and cytogenetic abnormalities are required for the malignant transformation of germinal center-experienced HRS cell precursors. Chromosomal instability and the influence of endogenous mutational processes are critical in this regard, by impacting genes involved in key signaling pathways that promote the survival and proliferation of HRS cells and their escape from immune destruction. Here we review the principal features, known risk factors and lymphomagenic mechanisms relevant to newly diagnosed CHL, with an emphasis on those most applicable to young people.

Prognostic Markers within the Tumour Microenvironment in Classical Hodgkin Lymphoma

Classical Hodgkin lymphoma (cHL) accounts for 0.4% of all new cancer cases globally. Despite high cure rates with standard treatment, approximately 15% of patients still experience relapsed or refractory (RR) disease, and many of these eventually die from lymphoma-related causes. Exciting new targeted agents such as anti-PD-1 agents and brentuximab vedotin have changed the therapeutic paradigm beyond chemotherapy and radiotherapy alone. Advances in understanding of the molecular biology are providing insights in the context of novel therapies. The signature histology of cHL requires the presence of scant malignant Hodgkin Reed-Sternberg cells (HRSCs) surrounded by a complex immune-rich tumour microenvironment (TME). The TME cellular composition strongly influences outcomes, yet knowledge of the precise characteristics of TME cells and their interactions with HRSCs is evolving. Novel high-throughput technologies and single-cell sequencing allow deeper analyses of the TME and mechanisms elicited by HRSCs to propagate growth and avoid immune response. In this review, we explore the evolution of knowledge on the prognostic role of immune cells within the TME and provide an up-to-date overview of emerging prognostic data on cHL from new technologies that are starting to unwind the complexity of the cHL TME and provide translational insights into how to improve therapy in the clinic.

Shared Pathogenicity Features and Sequences between EBV, SARS-CoV-2, and HLA Class I Molecule-binding Motifs with a Potential Role in Autoimmunity

Epstein-Barr virus (EBV) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are extraordinary in their ability to activate autoimmunity as well as to induce diverse autoimmune diseases. Here we reviewed the current knowledge on their relation. Further, we suggested that molecular mimicry could be a possible common mechanism of autoimmunity induction in the susceptible individuals infected with SARS-CoV-2. Molecular mimicry between SARS-CoV-2 and human proteins, and EBV and human proteins, are present. Besides, relation of the pathogenicity associated with both coronavirus diseases and EBV supports the notion. As a proof-of-the-concept, we investigated 8mer sequences with shared 5mers of SARS-CoV-2, EBV, and human proteins, which were predicted as epitopes binding to the same human leukocyte antigen (HLA) supertype representatives. We identified significant number of human peptide sequences with predicted-affinities to the HLA-A*02:01 allele. Rest of the peptide sequences had predicted-affinities to the HLA-A*02:01, HLA-B*40:01, HLA-B*27:05, HLA-A*01:01, and HLA-B*39:01 alleles. Carriers of these serotypes can be under a higher risk of autoimmune response induction upon getting infected, through molecular mimicry-based mechanisms common to SARS-CoV-2 and EBV infections. We additionally reviewed established associations of the identified proteins with the EBV-related pathogenicity and with the autoimmune diseases.

The impact of HLA polymorphism on herpesvirus infection and disease

Human Leukocyte Antigens (HLA) are cell surface molecules, central in coordinating innate and adaptive immune responses, that are targets of strong diversifying natural selection by pathogens. Of these pathogens, human herpesviruses have a uniquely ancient relationship with our species, where coevolution likely has reciprocating impact on HLA and viral genomic diversity. Consistent with this notion, genetic variation at multiple HLA loci is strongly associated with modulating immunity to herpesvirus infection. Here, we synthesize published genetic associations of HLA with herpesvirus infection and disease, both from case/control and genome-wide association studies. We analyze genetic associations across the eight human herpesviruses and identify HLA alleles that are associated with diverse herpesvirus-related phenotypes. We find that whereas most HLA genetic associations are virus- or disease-specific, HLA-A*01 and HLA-A*02 allotypes may be more generally associated with immune susceptibility and control, respectively, across multiple herpesviruses. Connecting genetic association data with functional corroboration, we discuss mechanisms by which diverse HLA and cognate receptor allotypes direct variable immune responses during herpesvirus infection and pathogenesis. Together, this review examines the complexity of HLA-herpesvirus interactions driven by differential T cell and Natural Killer cell immune responses.

Comprehensive Analysis of Epstein-Barr Virus LMP2A-Specific CD8+ and CD4+ T Cell Responses Restricted to Each HLA Class I and II Allotype Within an Individual

Latent membrane protein 2A (LMP2A), a latent Ag commonly expressed in Epstein-Barr virus (EBV)-infected host cells, is a target for adoptive T cell therapy in EBV-associated malignancies. To define whether individual human leukocyte antigen (HLA) allotypes are used preferentially in EBV-specific T lymphocyte responses, LMP2A-specific CD8+ and CD4+ T cell responses in 50 healthy donors were analyzed by ELISPOT assay using artificial Ag-presenting cells expressing a single allotype. CD8+ T cell responses were significantly higher than CD4+ T cell responses. CD8+ T cell responses were ranked from highest to lowest in the order HLA-A, HLA-B, and HLA-C loci, and CD4+ T cell responses were ranked in the order HLA-DR, HLA-DP, and HLA-DQ loci. Among the 32 HLA class I and 56 HLA class II allotypes, 6 HLA-A, 7 HLA-B, 5 HLA-C, 10 HLA-DR, 2 HLA-DQ, and 2 HLA-DP allotypes showed T cell responses higher than 50 spot-forming cells (SFCs)/5×105 CD8+ or CD4+ T cells. Twenty-nine donors (58%) showed a high T cell response to at least one allotype of HLA class I or class II, and 4 donors (8%) had a high response to both HLA class I and class II allotypes. Interestingly, we observed an inverse correlation between the proportion of LMP2A-specific T cell responses and the frequency of HLA class I and II allotypes. These data demonstrate the allele dominance of LMP2A-specific T cell responses among HLA allotypes and their intra-individual dominance in response to only a few allotypes in an individual, which may provide useful information for genetic, pathogenic, and immunotherapeutic approaches to EBV-associated diseases.

Killer Cell Immunoglobulin-Like Receptor Haplotype B Modulates Susceptibility to EBV-Associated Classic Hodgkin Lymphoma

Tumor cells of classic Hodgkin lymphoma (cHL) are derived from antigen presenting B cells that are infected by Epstein Barr virus (EBV) in ~30% of patients. Polymorphic Killer cell immunoglobulin-like receptors (KIRs) expressed on NK cells interact with human leukocyte antigen (HLA) class I and play a key role in immune surveillance against virally infected cells and tumor cells. We investigated the effect of KIR types on cHL susceptibility overall (n=211) and in EBV-stratified subgroups using the Dutch GoNL cohort as controls (n=498). The frequency of the KIR haplotype B subgroup was significantly different between EBV+ and EBV− cHL patients (62% vs. 77%, p=0.04) and this difference was more pronounced in nodular sclerosis (NS) cHL (49% vs. 79%, p=0.0003). The frequency of KIR haplotype B subgroup was significantly lower in EBV+ NS cHL compared to controls (49% vs. 67%, p=0.01). Analyses of known KIR – HLA interaction pairs revealed lower carrier frequencies of KIR2DS2 – HLA-C1 (29% vs. 46%, p=0.03) and KIR2DL2 – HLA-C1 (29% vs. 45%, p=0.04) in EBV+ NS cHL patients compared to controls. Carriers of the KIR haplotype B subgroup are less likely to develop EBV+ NS cHL, probably because of a more efficient control over EBV-infected B cells.

HLA Expression in Relation to HLA Type in Classic Hodgkin Lymphoma Patients

Simple Summary

Classic Hodgkin lymphoma (cHL) is a B-cell malignancy with involvement of Epstein–Barr virus (EBV) in about 30% of the European population. The risk to develop cHL is strongly linked to genetic variants in the human leukocyte antigen (HLA) genomic region and to certain HLA alleles. This may be caused by the function of HLA alleles, or by genetic linkage to non-HLA genes. HLA can present EBV-derived and tumour-cell specific antigens and this may lead to anti-tumour immune responses. However, the tumour cells downregulate HLA expression in a proportion of the cases, which may result in immune escape. In this study, we tested whether the loss of HLA expression is related to the presence of certain protective HLA alleles. We found that loss and retention of HLA expression is indeed associated with presence of known susceptibility HLA alleles. These findings suggest that HLA itself is involved in development of cHL.

Abstract

Several human leukocyte antigen (HLA) alleles are strongly associated with susceptibility to classic Hodgkin lymphoma (cHL), also in subgroups stratified for presence of the Epstein–Barr virus (EBV). We tested the hypothesis that the pressure on cHL tumour cells to lose HLA expression is associated with HLA susceptibility alleles. A meta-analysis was carried out to identify consistent protective and risk HLA alleles in a combined cohort of 839 cHL patients from the Netherlands and the United Kingdom. Tumour cell HLA expression was studied in 338 cHL cases from these two cohorts and correlated to the presence of specific susceptibility HLA alleles. Carriers of the HLA-DRB1*07 protective allele frequently lost HLA class II expression in cHL overall. Patients carrying the HLA-DRB1*15/16 (DR2) risk allele retained HLA class II expression in EBV− cHL and patients with the HLA-B*37 risk allele retained HLA class I expression more frequently than non-carriers in EBV+ cHL. The other susceptibility alleles showed no significant differences in expression. Thus, HLA expression by tumour cells is associated with a subset of the protective and risk alleles. This strongly suggests that HLA associations in cHL are related to peptide binding capacities of specific HLA alleles.

Intratumoral T-cell receptor repertoire is predictive of interim PET scan results in patients with diffuse large B-cell lymphoma treated with rituximab/cyclophosphamide/doxorubicin/prednisolone/vincristine (R-CHOP) chemoimmunotherapy

Objectives

A diverse intratumoral T‐cell receptor (TCR) repertoire is associated with improved survival in diffuse large B‐cell lymphoma (DLBCL) treated with rituximab/cyclophosphamide/doxorubicin/prednisolone/vincristine (R‐CHOP) chemoimmunotherapy. We explored the impact of intratumoral TCR repertoire on interim PET (iPET) done after four cycles of R‐CHOP, the relationships between intratumoral and circulating repertoire, and the phenotypes of expanded clonotypes.

Methods

We sequenced the third complementarity‐determining region of TCRβ in tumor samples, blood at pre‐therapy and after four cycles of R‐CHOP in 35 patients enrolled in ALLGNHL21 trial in high‐risk DLBCL. We correlated the TCR diversity metrics with iPET status, gene expression profiles and HLA‐class I genotypes. We then sequenced the FACS‐sorted peripheral blood T cells in six patients, and pentamer‐sorted EBV‐specific CD8⁺ T cells in one patient from this cohort.

Results

Compared with iPET⁻ patients, the intratumoral TCR repertoire in iPET⁺ patients was characterised by higher cumulative frequency of abundant clonotypes and higher productive clonality. There was a variable overlap between circulating and intratumoral repertoires, with the dominant intratumoral clonotypes more likely to be detected in the blood. The majority of shared clonotypes were CD8⁺ PD‐1^HI T cells, and CD8⁺ T cells had the largest clonal expansions in tumor and blood. In a patient with EBV⁺ DLBCL, EBV‐specific intratumoral clonotypes were trackable in the blood.

Conclusion

This study demonstrates that clonally expanded intratumoral TCR repertoires are associated with iPET⁺ and that the blood can be used to track tumor‐associated antigen‐specific clonotypes. These findings assist the rationale design and therapeutic monitoring of immunotherapeutic strategies in DLBCL.

Immunity reloaded: Deconstruction of the PD-1 axis in B cell lymphomas

Over the past decade therapies targeting the PD-1 axis with monoclonal antibodies to reinstate host immune function have revolutionized the clinical management of some cancers but have had minimal impact on others. This dichotomy is exemplified by B cell lymphomas. Whilst striking results are observed in classical Hodgkin Lymphoma (cHL) and Primary Mediastinal B Cell Lymphoma (PMBL), responses in other B cell lymphomas are infrequent. Even with cHL and PMBL, responses are not always durable and adverse effects can result in treatment discontinuation. A more nuanced approach to manipulate the PD-1 axis is required before the full benefits of PD-1 axis blockade can be realised. In this review, we provide an outline of PD-1 axis biology, including the range of cellular expression, the molecular mechanisms underlying regulation and the impacts of downstream signalling. These may permit the development of alternate strategies to PD-1 axis blockade to enhance the therapeutic efficacy in B cell lymphomas.

Interaction between ERAP Alleles and HLA Class I Types Support a Role of Antigen Presentation in Hodgkin Lymphoma Development

Simple Summary

Hodgkin lymphoma (HL) is a common lymphoma in young adults derived from B cells. Emerging evidence suggests that antigen presentation by the malignant B cells is critically involved in HL pathogenesis. In fact, genetic variants of the antigen presenting Human Leukocyte Antigens (HLA) are strongly associated with HL susceptibility. Interestingly, the endoplasmic reticulum aminopeptidase (ERAP)1 and ERAP2 genes, that code for enzymes that process antigens, also appear to be associated. In this study, we show that genetic variants of ERAP genes strongly affect expression levels of ERAP1 and ERAP2. In addition, we find that certain ERAP variants interact with specific HLA class I types in HL patients. This suggests that mechanisms that determine the repertoire of antigens that are presented to the immune system, affect the chance of developing HL. Our findings therefore support a prominent role of antigen presentation in HL susceptibility.

Abstract

Genetic variants in the HLA region are the strongest risk factors for developing Hodgkin lymphoma (HL), suggesting an important role for antigen presentation. This is supported by another HL-associated genomic region which contains the loci of two enzymes that process endogenous proteins to peptides to be presented by HLA class I, i.e., endoplasmic reticulum aminopeptidase 1 (ERAP1) and ERAP2. We hypothesized that ERAP and HLA class I type interact in HL susceptibility, as shown previously for several autoimmune diseases. We detected ERAP1 and ERAP2 expression in tumor cells and cells in the microenvironment in primary HL tissue samples. Seven ERAP SNPs and ERAP1 haplotypes showed strong associations with RNA and protein levels of ERAP1 and ERAP2 in LCLs and HL cell lines. Analysis of HLA class I types, ERAP SNPs and ERAP haplotypes by direct genotyping or imputation from genome-wide association data in 390 HL patients revealed significant interactions between HLA-A11, rs27038 and the rs27038 associated ERAP haplotype, as well as between HLA-Cw2 and rs26618. In conclusion, our results show that ERAP and HLA class I interact in genetic susceptibility to HL, providing further evidence that antigen presentation is an important process in HL susceptibility and pathogenesis.

The Evolving Knowledge on T and NK Cells in Classic Hodgkin Lymphoma: Insights into Novel Subsets Populating the Immune Microenvironment

Simple Summary

In classic Hodgkin lymphoma, T and NK cells constitute a significant fraction of the reactive microenvironment established by malignant Hodgkin Reed–Sternberg cells. Despite their abundance, T and NK cells remain largely ineffective because of two coordinated levels of immune evasion. The first is based on the acquisition of regulatory properties or exhausted phenotypes that cripple their antitumor activity. The second is represented by their peculiar spatial distribution, with the most immunosuppressive subpopulations lying in close proximity of neoplastic cells. Recent discoveries about the functional role and the spatial orientation of T and NK cells in classic Hodgkin lymphoma are the focus of this review.

Abstract

Classic Hodgkin lymphoma (cHL) is a unique lymphoid neoplasm characterized by extensive immune infiltrates surrounding rare malignant Hodgkin Reed–Sternberg (HRS) cells. Different subsets of T and NK cells have long been recognized in the cHL microenvironment, yet their distinct contribution to disease pathogenesis has remained enigmatic. Very recently, novel platforms for high dimensional analysis of immune cells, such as single-cell RNA sequencing and mass cytometry, have revealed unanticipated insights into the composition of T- and NK-cell compartments in cHL. Advances in imaging techniques have better defined specific T-helper subpopulations physically interacting with neoplastic cells. In addition, the identification of novel cytotoxic subsets with an exhausted phenotype, typically enriched in cHL milieu, is shedding light on previously unrecognized immune evasion mechanisms. This review examines the immunological features and the functional properties of T and NK subsets recently identified in the cHL microenvironment, highlighting their pathological interplay with HRS cells. We also discuss how this knowledge can be exploited to predict response to immunotherapy and to design novel strategies to improve PD-1 blockade efficacy.

Genetic aberrations of NLRC5 are associated with downregulated MHC-I antigen presentation and impaired T-cell immunity in follicular lymphoma

Follicular lymphoma (FL) is the most common indolent non-Hodgkin lymphoma. Twenty to twenty-five percent of FL patients have progression of disease within 24 months. These patients may benefit from immunotherapy if intact antigen presentation is present. Molecular mechanisms impairing major histocompatibility complex class-I (MHC-I) in FL remain undefined. Here, by sequencing of 172 FL tumours, we found the MHC-I transactivator NLRC5 was the most frequent gene abnormality in the MHC-I pathway. Pyrosequencing showed that epigenetic silencing of the NLRC5 promoter occurred in 30% of cases and was mutually exclusive to copy number loss (CNL) in NLRC5 (∼6% of cases). Hypermethylation and CNLs ("NLRC5 aberrant") had reduced NLRC5 gene expression compared to wild-type (WT) cases. By NanoString, there was reduced gene expression of the MHC-I pathway in aberrant tissues, including immunoproteasome components (PSMB8 and PSMB9), peptide transporters of antigen processing (TAP1), and MHC-I (HLA-A), compared to WT. By immunofluorescent microscopy, fewer NLRC5 protein-expressing malignant B-cells were observed in NLRC5 aberrant tissue sections compared to NLRC5 WT (P < .01). Consistent with a pivotal role in the activation of CD8+ T-cells, both CD8 and CD137 strongly correlated with NLRC5 expression (both r > 0.7; P < .0001). Further studies are required to determine whether patients with aberrant NLRC5 have a diminished response to immunotherapy.

Classic Hodgkin lymphoma post-transplant lymphoproliferative disorders (PTLD) are often preceded by discordant PTLD subtypes

Classic Hodgkin lymphoma (CHL) is the rarest post-transplant lymphoproliferative disorder (PTLD) subtype. Few cases of patients with metachronous discordant PTLD episodes including CHL-PTLD have been reported, but the incidence of and risk factors for this phenomenon are unknown. Patients with CHL-PTLD were identified from an institutional PTLD database. Of 13 patients identified with CHL-PTLD six (46%) had antecedent non-CHL-PTLD: three had polymorphic PTLD, two monomorphic PTLD, and one nondestructive PTLD. Patients with prior metachronous non-CHL-PTLD were younger at transplant and had a longer latency time to CHL-PTLD post-transplant. The prevalence of EBV seronegativity at transplant was high in both groups, but prolonged high-level EBV DNAemia only occurred in some with metachronous non-CHL-PTLD. In conclusion, patients with CHL-PTLD have metachronous non-CHL-PTLD diagnoses with discordant histology more commonly than previously recognized. Primary EBV infection with chronically elevated EBV viral loads may represent unique risk factors for CHL-PTLD following an initial non-CHL-PTLD event.

Identification of Functional HLA-A*01 :01-Restricted EBV-LMP2-Specific T-cell Receptors

BACKGROUND

Adoptive transfer of genetically engineered T cells expressing antigen-specific T-cell receptors (TCRs), is an appealing therapeutic approach for Epstein-Barr virus (EBV)-associated malignancies of latency type II/III that express EBV-antigens (LMP1/2). Patients who are HLA-A*01:01pos could benefit from such products, since no T cells recognizing any EBV-derived peptide in this common HLA allele have been found thus far.

METHODS

HLA-A*01:01-restricted EBV-(LMP2)-specific T-cells were isolated using peptide-MHC-tetramers. Functionality was assessed by production of IFNγ and cytotoxicity when stimulated with EBV-LMP2-expressing cell-lines. Functionality of primary T cells transduced with HLA-A*01:01-restricted EBV-LMP2-specific TCRs was optimized by knocking out the endogenous TCR of primary T cells (ΔTCR) using CRISPR-Cas9 technology.

RESULTS

EBV-LMP2-specific T cells were successfully isolated and their TCRs were characterized. TCR gene-transfer in primary T cells resulted in specific peptide-MHC-tetramer binding and reactivity against EBV-LMP2-expressing cell-lines. The mean-fluorescence intensity of peptide-MHC-tetramer binding was increased 1.5-2 fold when the endogenous TCR of CD8pos T cells was knocked out. CD8pos/ΔTCR T cells modified to express EBV-LMP2-specific TCRs showed IFNγ secretion and cytotoxicity towards EBV-LMP2-expressing malignant cell-lines.

DISCUSSION

We isolated the first functional HLA-A*01:01-restricted EBV-LMP2-specific T-cell populations and TCRs, which can potentially be used in future TCR gene-therapy to treat EBV-associated latency type II/III malignancies.

LAG3: a novel immune checkpoint expressed by multiple lymphocyte subsets in diffuse large B-cell lymphoma

Blockade of the PD-1 axis has modest efficacy in diffuse large B-cell lymphoma (DLBCL), but data regarding LAG3 are sparse. The impact of LAG3 digital gene expression was tested in 309 patients with DLBCL treated with standard chemoimmunotherapy. Cellular distribution of LAG3 protein was determined by immunohistochemistry and flow cytometry. In tumor-infiltrating lymphocytes (TILs), LAG3 expression was highest on CD4+ regulatory T cells (Tregs) and was also highly expressed on CD8+ T cells compared with CD4+ non-Tregs (both P = .008). LAG3high TILs were enriched in PD-1 and TIM-3. LAG3 was also expressed on a proportion of malignant B cells, and these patients had significantly higher LAG3 messenger RNA in their biopsies (P = .03). LAG3high gene expression was associated with inferior survival in discovery/validation cohorts, independent of cell of origin and the international prognostic index. Patients who were PD-L1high were fivefold more likely to be LAG3high (P < .0001). Patients who were LAG3high/PD-L1high had an inferior progression-free survival (P = .011) and overall survival (P = .005) compared with patients who were LAG3low/PD-L1high. Digital spatial protein analysis confirms LAG3 expression on T cells and, surprisingly, tumor-associated macrophages (TAMs) at higher levels than found on CD20+ B cells in the tumor microenvironment. LAG3 is frequently expressed on CD4+ Tregs and CD8+ TILs, typically with other immune checkpoints, and is also present in a proportion of malignant B cells in DLBCL and in areas enriched for TAMs. LAG3high expression is associated with poor outcome independent of conventional prognosticators.

Progression of Disease Within 24 Months in Follicular Lymphoma Is Associated With Reduced Intratumoral Immune Infiltration

PURPOSE

Understanding the immunobiology of the 15% to 30% of patients with follicular lymphoma (FL) who experience progression of disease within 24 months (POD24) remains a priority. Solid tumors with low levels of intratumoral immune infiltration have inferior outcomes. It is unknown whether a similar relationship exists between POD24 in FL.

PATIENTS AND METHODS

Digital gene expression using a custom code set—five immune effector, six immune checkpoint, one macrophage molecules—was applied to a discovery cohort of patients with early- and advanced-stage FL (n = 132). T-cell receptor repertoire analysis, flow cytometry, multispectral immunofluorescence, and next-generation sequencing were performed. The immune infiltration profile was validated in two independent cohorts of patients with advanced-stage FL requiring systemic treatment (n = 138, rituximab plus cyclophosphamide, vincristine, prednisone; n = 45, rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone), with the latter selected to permit comparison of patients experiencing a POD24 event with those having no progression at 5 years or more.

RESULTS

Immune molecules showed distinct clustering, characterized by either high or low expression regardless of categorization as an immune effector, immune checkpoint, or macrophage molecule. Low programmed death-ligand 2 (PD-L2) was the most sensitive/specific marker to segregate patients with adverse outcomes; therefore, PD-L2 expression was chosen to distinguish immune infiltration^HI (ie, high PD-L2) FL biopsies from immune infiltration^LO (ie, low PD-L2) tumors. Immune infiltration^HI tissues were highly infiltrated with macrophages and expanded populations of T-cell clones. Of note, the immune infiltration^LO subset of patients with FL was enriched for POD24 events (odds ratio [OR], 4.32; c-statistic, 0.81; P = .001), validated in the independent cohorts (rituximab plus cyclophosphamide, vincristine, prednisone: OR, 2.95; c-statistic, 0.75; P = .011; and rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone: OR, 7.09; c-statistic, 0.88; P = .011). Mutations were equally proportioned across tissues, which indicated that degree of immune infiltration is capturing aspects of FL biology distinct from its mutational profile.

CONCLUSION

Assessment of immune-infiltration by PD-L2 expression is a promising tool with which to help identify patients who are at risk for POD24.

The tumour microenvironment is immuno-tolerogenic and a principal determinant of patient outcome in EBV-positive diffuse large B-cell lymphoma

OBJECTIVE

Epstein-Barr virus-positive diffuse large B-cell lymphoma (EBV^-pos DLBCL) is a recently identified entity. Data regarding outcome to frontline immuno-chemotherapy are conflicting. Although the prognostic impact of the tumour microenvironment (TME) in EBV^-neg DLBCL is well-established, it remains untested whether the TME influences survival in EBV^-pos DLBCL. There are no data with new digital gene expression technologies that simultaneously interrogate the virus, B cells and the tumour microenvironment (TME).

METHODS

We used the NanoString™ platform in a population-based cohort of 433 patients to establish if the technology could detect EBV in the tumour biopsies and to investigate the influence that EBV has on the complex tumour microenvironment of DLBCL.

RESULTS

Incidence of EBV^-pos DLBCL was 6.9% with 5-year survival of 65% vs 82% in EBV^-neg DLBCL (P = 0.018). EBV^-pos tissues had similar expression of T-cell genes compared to EBV^-neg DLBCL but higher levels of the antigen-presenting molecule B2M. This was countered by elevated PD-L1, PD-L2, LAG3 and TIM3 immune checkpoints and a higher CD163/CD68 "M2" macrophage score.

CONCLUSION

In EBV^-pos DLBCL, the TME is immuno-tolerogenic and may explain the poor outcomes seen in this subtype of DLBCL.

Epstein-Barr Virus and the Human Leukocyte Antigen Complex

Purpose

While most adults are infected Epstein-Barr virus (EBV), 3-5% remain uninfected. The human leukocyte antigen (HLA) complex, which controls many pathogens, may influence infection and disease associated with EBV.

Recent Findings

Numerous EBV proteins and miRNAs down-regulate HLA class I and II expression on the cell surface. HLA class II functions as a receptor for EBV entry into B cells. Specific HLA class II alleles correlate with the susceptibility of B cells to EBV infection in vitro and with EBV seropositivity or seronegativity of humans. HLA class I polymorphisms correlate with development and severity of EBV infectious mononucleosis and with the risk of several virus-associated malignancies including nasopharyngeal carcinoma, Hodgkin lymphoma, and post-transplant lymphoproliferative disease.

Significance

These findings indicate that while EBV has evolved to use MHC class II as a receptor for virus entry, polymorphisms in MHC class II and class I influence virus infection and disease.

Circulating cell-free miR-494 and miR-21 are disease response biomarkers associated with interim-positron emission tomography response in patients with diffuse large B-cell lymphoma

MicroRNA (miRNA)s are dysregulated in Diffuse large B-cell lymphoma (DLBCL), where they reflect the malignant B-cells and the immune infiltrate within the tumor microenvironment. There remains a paucity of data in DLBCL regarding cell-free (c-f) miRNA as disease response biomarkers. Immunosuppressive monocyte/macrophages, which are enriched in DLBCL, are disease response markers in DLBCL, with miRNA key regulators of their immunosuppressive function. Our aim was to determine whether plasma miRNA that reflect the activity of the malignant B-cell and/or immunosuppressive monocytes/macrophages, have value as minimally-invasive disease response biomarkers in DLBCL.

Quantification of 99 DLBCL tissues, to select miRNA implicated in immunosuppressive monocytes/macrophage biology, found miR-494 differentially elevated. In a discovery cohort (22 patients), pre-therapy c-f miR-494 and miR-21 but not miR-155 were raised relative to healthy plasma. Both miR-494 and miR-21 levels 3-6 months reduced post immuno-chemotherapy. The validation cohort (56 patients) was from a prospective clinical trial. Interestingly, in sequential samples both miRNAs decreased in patients becoming Positron Emission Tomography/Computerized Tomography (PET/CT)-ve, but not in those remaining interim-PET/CT+. Patient monocytes were phenotypically and functionally immunosuppressive with ex-vivo monocyte depletion enhancing T-cell proliferation in patient but not healthy samples. Pre-therapy monocytes showed an immunosuppressive transcriptome and raised levels of miR-494. MiR-494 was present in all c-f nanoparticle fractions but was most readily detectable in unfractionated plasma.

Circulating c-f miR-494 and miR-21 are disease response biomarkers with differential response stratified by interim-PET/CT in patients with DLBCL. Further studies are required to explore their manipulation as potential therapeutic targets.

Proteome-wide analysis of CD8+ T cell responses to EBV reveals differences between primary and persistent infection

Human herpesviruses are antigenically rich agents that induce strong CD8+T cell responses in primary infection yet persist for life, continually challenging T cell memory through recurrent lytic replication and potentially influencing the spectrum of antigen-specific responses. Here we describe the first lytic proteome-wide analysis of CD8+ T cell responses to a gamma1-herpesvirus, Epstein-Barr virus (EBV), and the first such proteome-wide analysis of primary versus memory CD8+ T cell responses to any human herpesvirus. Primary effector preparations were generated directly from activated CD8+ T cells in the blood of infectious mononucleosis (IM) patients by in vitro mitogenic expansion. For memory preparations, EBV-specific cells in the blood of long-term virus carriers were first re-stimulated in vitro by autologous dendritic cells loaded with a lysate of lytically-infected cells, then expanded as for IM cells. Preparations from 7 donors of each type were screened against each of 70 EBV lytic cycle proteins in combination with the donor's individual HLA class I alleles. Multiple reactivities against immediate early (IE), early (E) and late (L) lytic cycle proteins, including many hitherto unrecognised targets, were detected in both contexts. Interestingly however, the two donor cohorts showed a different balance between IE, E and L reactivities. Primary responses targeted IE and a small group of E proteins preferentially, seemingly in line with their better presentation on the infected cell surface before later-expressed viral evasins take full hold. By contrast, target choice equilibrates in virus carriage with responses to key IE and E antigens still present but with responses to a select subset of L proteins now often prominent. We infer that, for EBV at least, long-term virus carriage with its low level virus replication and lytic antigen release is associated with a re-shaping of the virus-specific response.

Hypothesis: Multiple sclerosis is caused by three-hits, strictly in order, in genetically susceptible persons

Multiple Sclerosis is a chronic, progressive and debilitating neurological disease which, despite extensive study for over 100 years, remains of enigmatic aetiology. Drawn from the epidemiological evidence, there exists a consensus that there are environmental (possibly infectious) factors that contribute to disease pathogenesis that have not yet been fully elucidated. Here we propose a three-tiered hypothesis: 1) a clinic-epidemiological model of multiple sclerosis as a rare late complication of two sequential infections (with the temporal sequence of infections being important); 2) a proposal that the first event is helminthic infection with Enterobius Vermicularis, and the second is Epstein Barr Virus infection; and 3) a proposal for a testable biological mechanism, involving T-Cell exhaustion for Epstein-Barr Virus protein LMP2A. We believe that this model satisfies some of the as-yet unexplained features of multiple sclerosis epidemiology, is consistent with the clinical and neuropathological features of the disease and is potentially testable by experiment. This model may be generalizable to other autoimmune diseases.

Characterization of CSF2A fusion gene and its effect on Epstein-Barr virus-positive tumor cells

We build the latent membrane protein gene latent membrane protein 2A (LMP2A) and the granulocyte-macrophase colony-stimulating factor (GM-CSF) gene fusion gene (CSF2A) and discuss how the CSF2A fusion protein influenced the proliferation and apoptosis of Epstein-Barr virus-positive (EBV⁺ ) tumor cells. Reverse-transcription polymerase chain reaction (RT-PCR) method was used to amplify the LMP2A gene and GM-CSF gene fragments, respectively, according to the principle of overlap extension in the coding (Gly4Ser)₃ polypeptide gene fragments of DNA restructured under the connection. The CSF2A gene could be connected with the pIRES2-enhanced green fluorescent protein vector by recombinant DNA technology and identified by enzyme electrophoresis analysis and DNA sequencing. Then, the recombinant vector was transfected into dendritic cells (DCs); RT-PCR and Western blot analysis were used for testing the CSF2A gene messenger RNA and protein expression. The impacts of CSF2A on the proliferation and apoptosis of EBV⁺ tumor cells were determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and Hochest 33342 staining. We successfully obtained the recombinant vector named pIRES2-CSF2A. The expression of CSF2A could be detected by transfecting pIRES2-CSF2A into DCs. The DCs were cocultured with T lymphocytes and then acted on the EBV⁺ CNE2 nasopharyngeal carcinoma cells. MTT assay showed that the inhibiting effect of CSF2A obviously increased and the time dependency (**P < 0.01, *P < 0.05) also existed. Hochest 33342 staining showed apoptosis morphological changes of cells in nucleus staining and generated the apoptotic body. Apoptosis cells of the pIRES2-CSF2A group increased significantly at 48 hours. The results showed that the pIRES2-CSF2A recombinant vector was effectively transfected into DCs and the fusion gene CSF2A could promote EBV⁺ CNE2 cell apoptosis, laying the foundation for the specificity of EBV⁺ tumor targeting immune gene therapy in the future.

Immune evasion via PD-1/PD-L1 on NK cells and monocyte/macrophages is more prominent in Hodgkin lymphoma than DLBCL

Much focus has been on the interaction of programmed cell death ligand 1 (PD-L1) on malignant B cells with programmed cell death 1 (PD-1) on effector T cells in inhibiting antilymphoma immunity. We sought to establish the contribution of natural killer (NK) cells and inhibitory CD163+ monocytes/macrophages in Hodgkin lymphoma (cHL) and diffuse large B-cell lymphoma (DLBCL). Levels of PD-1 on NK cells were elevated in cHL relative to DLBCL. Notably, CD3-CD56hiCD16-ve NK cells had substantially higher PD-1 expression relative to CD3-CD56dimCD16+ cells and were expanded in blood and tissue, more marked in patients with cHL than patients with DLBCL. There was also a raised population of PD-L1-expressing CD163+ monocytes that was more marked in patients with cHL compared with patients with DLBCL. The phenotype of NK cells and monocytes reverted back to normal once therapy (ABVD [doxorubicin 25 mg/m2, bleomycin 10 000 IU/m2, vinblastine 6 mg/m2, dacarbazine 375 mg/m2, all given days 1 and 15, repeated every 28 days] or R-CHOP [rituximab 375 mg/m2, cyclophosphamide 750 mg/m2 IV, doxorubicin 50 mg/m2 IV, vincristine 1.4 mg/m2 (2 mg maximum) IV, prednisone 100 mg/day by mouth days 1-5, pegfilgrastim 6 mg subcutaneously day 4, on a 14-day cycle]) had commenced. Tumor-associated macrophages (TAMs) expressed high levels of PD-L1/PD-L2 within diseased lymph nodes. Consistent with this, CD163/PD-L1/PD-L2 gene expression was also elevated in cHL relative to DLBCL tissues. An in vitro functional model of TAM-like monocytes suppressed activation of PD-1hi NK cells, which was reversed by PD-1 blockade. In line with these findings, depletion of circulating monocytes from the blood of pretherapy patients with cHL and patients with DLBCL enhanced CD3-CD56hiCD16-ve NK-cell activation. We describe a hitherto unrecognized immune evasion strategy mediated via skewing toward an exhausted PD-1-enriched CD3-CD56hiCD16-ve NK-cell phenotype. In addition to direct inhibition of NK cells by the malignant B cell, suppression of NK cells can occur indirectly by PD-L1/PD-L2-expressing TAMs. The mechanism is more prominent in cHL than DLBCL, which may contribute to the clinical sensitivity of cHL to PD-1 blockade.

The Microenvironment in Epstein-Barr Virus-Associated Malignancies

The Epstein–Barr virus (EBV) can cause a wide variety of cancers upon infection of different cell types and induces a highly variable composition of the tumor microenvironment (TME). This TME consists of both innate and adaptive immune cells and is not merely an aspecific reaction to the tumor cells. In fact, latent EBV-infected tumor cells utilize several specific mechanisms to form and shape the TME to their own benefit. These mechanisms have been studied largely in the context of EBV+ Hodgkin lymphoma, undifferentiated nasopharyngeal carcinoma, and EBV+ gastric cancer. This review describes the composition, immune escape mechanisms, and tumor cell promoting properties of the TME in these three malignancies. Mechanisms of susceptibility which regularly involve genes related to immune system function are also discussed, as only a small proportion of EBV-infected individuals develops an EBV-associated malignancy.

The T-cell Receptor Repertoire Influences the Tumor Microenvironment and Is Associated with Survival in Aggressive B-cell Lymphoma

Purpose: To investigate the relationship between the intra-tumoral T-cell receptor (TCR) repertoire and the tumor microenvironment (TME) in de novo diffuse large B-cell lymphoma (DLBCL) and the impact of TCR on survival.Experimental Design: We performed high-throughput unbiased TCRβ sequencing on a population-based cohort of 92 patients with DLBCL treated with conventional (i.e., non-checkpoint blockade) frontline "R-CHOP" therapy. Key immune checkpoint genes within the TME were digitally quantified by nanoString. The primary endpoints were 4-year overall survival (OS) and progression-free survival (PFS).Results: The TCR repertoire within DLBCL nodes was abnormally narrow relative to non-diseased nodal tissues (P < 0.0001). In DLBCL, a highly dominant single T-cell clone was associated with inferior 4-year OS rate of 60.0% [95% confidence interval (CI), 31.7%-79.6%], compared with 79.8% in patients with a low dominant clone (95% CI, 66.7%-88.5%; P = 0.005). A highly dominant clone also predicted inferior 4-year PFS rate of 46.6% (95% CI, 22.5%-76.6%) versus 72.6% (95% CI, 58.8%-82.4%, P = 0.008) for a low dominant clone. In keeping, clonal expansions were most pronounced in the EBV⁺ DLBCL subtype that is known to express immunogenic viral antigens and is associated with particularly poor outcome. Increased T-cell diversity was associated with significantly elevated PD-1, PD-L1, and PD-L2 immune checkpoint molecules.Conclusions: Put together, these findings suggest that the TCR repertoire is a key determinant of the TME. Highly dominant T-cell clonal expansions within the TME are associated with poor outcome in DLBCL treated with conventional frontline therapy. Clin Cancer Res; 23(7); 1820-8. ©2016 AACR.

HLA expression and HLA type associations in relation to EBV status in Hispanic Hodgkin lymphoma patients

A proportion of classical Hodgkin lymphomas harbor the Epstein Barr virus (EBV). We previously demonstrated that associations between Human Leukocyte Antigen (HLA) alleles and susceptibility to EBV+ classical Hodgkin lymphoma differ between European and Chinese populations. Data on Hispanic populations is missing. Here we examined the association between HLA type, tumor cell HLA expression and other characteristics in Hispanic Hodgkin lymphoma patients. Hispanic Hodgkin lymphoma patients diagnosed at the Los Angeles County-University of Southern California Medical Center from 2000–2012 were included (n = 65). Formalin-fixed paraffin-embedded tumor tissue was analyzed for EBV by in situ hybridization and for HLA class I and class II expression by immunohistochemistry. HLA typing was performed by HLA-A specific quantitative PCR of genomic DNA from tissue. Thirty patients (46%) had EBV+ tumors. Expression of HLA class I (p = 0.0006) was significantly associated with EBV+ tumor status in Hispanic patients, similar to Europeans and Chinese. A positive association between HLA class II expression and EBV+ tumor status, as present in large studies in Europeans, was not found (p = 0.06). The prevalences of the specific European HLA-A*01 risk and European HLA-A*02 protective types were not significantly associated with EBV+ tumors among these Hispanic patients, however numbers were too low to draw firm conclusions. The HLA-A*02:07 allele, that is associated with EBV+ Hodgkin lymphoma in Chinese, was absent. In conclusion, the association between EBV positivity in tumor cells and HLA class I expression appears to be consistent across different populations. Larger studies in Hispanics are needed to evaluate HLA allele susceptibility associations.

Thermal Stability of Heterotrimeric pMHC Proteins as Determined by Circular Dichroism Spectroscopy

T cell receptor (TCR) recognition of foreign peptide fragments, presented by peptide major histocompatibility complex (pMHC), governs T-cell mediated protection against pathogens and cancer. Many factors govern T-cell sensitivity, including the affinity of the TCR-pMHC interaction and the stability of pMHC on the surface of antigen presenting cells. These factors are particularly relevant for the peptide vaccination field, in which more stable pMHC interactions could enable more effective protection against disease. Here, we discuss a method for the determination of pMHC stability that we have used to investigate HIV immune escape, T-cell sensitivity to cancer antigens and mechanisms leading to autoimmunity.

Emerging therapies provide new opportunities to reshape the multifaceted interactions between the immune system and lymphoma cells

The acquisition of a complete neoplastic phenotype requires cancer cells to develop escape mechanisms from the host immune system. This phenomenon, commonly referred to as 'immune evasion,' represents a hallmark of cancers and results from a Darwinian selection of the fittest tumor clones. First reported in solid tumors, cancer immunoescape characterizes several hematological malignancies. The biological bases of cancer immunoescape have recently been disclosed and include: (i) impaired human leukocyte antigen-mediated cancer cell recognition (B2M, CD58, CTIIA, CD80/CD86, CD28 and CTLA-4 mutations); (ii) deranged apoptotic mechanisms (reduced pro-apoptotic signals and/or increased expression of anti-apoptotic molecules); and (iii) changes in the tumor microenvironment involving regulatory T cells and tumor-associated macrophages. These immune-escape mechanisms characterize both Hodgkin and non-Hodgkin (B and T cell) lymphomas and represent a promising target for new anti-tumor therapies. In the present review, the principles of cancer immunoescape and their role in human lymphomagenesis are illustrated. Current therapies targeting these pathways and possible applications for lymphoma treatment are also addressed.