Adenoviral gene transfer into dendritic cells efficiently amplifies the immune response to LMP2A antigen: A potential treatment strategy for Epstein-Barr virus-positive Hodgkin's lymphoma

Abstract

Improvements in radiochemotherapy have correspondingly improved the prognosis of patients with HodgkinЈs lymphoma. 1 However, patients resistant to the standard therapeutic approaches have a poor outcome. Moreover, both life expectancy and quality of life of patients cured of Hodgkin's lymphoma are significantly reduced by treatment-related mortality and morbidity. 2,3 These limitations of current treatment protocols illustrate the need for more effective and less toxic therapeutic approaches.In HodgkinЈs lymphomas, up to 49% of specimens have been shown to carry EBV DNA and to express EBV genes. 4,5 Adoptive immunotherapy with donor-derived, EBV-specific CTLs has significantly improved the clinical outcome of patients with EBV ϩ immunoblastic lymphoma after T cell-depleted allogeneic stemcell transplantation. 6,7 In an ongoing study, our group has successfully generated EBV-specific CTLs in patients with EBV ϩ Hodgkin's lymphoma. 8 After infusion, these CTLs home to the tumor sites, persist in the circulation for up to 9 months and produce transient clinical benefits. In this protocol, LCLs are used as EBV antigen-presenting cells. LCLs activate polyclonal CTL populations that are preferentially directed against the immunodominant EBNA3A, -3B and -3C EBV proteins. 9 These immunogenic proteins are not expressed in HRS cells. Instead, the EBV antigens on HRS cells are restricted to the expression of a subset of latent proteins, EBNA1, LMP1, LMP2A and BARF0. 10 -12 LCLs have limited efficacy at stimulating CTLs directed against these subdominant proteins.Targeting the EBV proteins expressed in EBV ϩ HRS cells is further complicated by their limited immunogenicity. EBNA1 is not processed for HLA class I presentation due to an internal glycine-alanine repeat region. 13 LMP1-specific CTL clones are rare in EBV ϩ donors, 14 and very few LMP1 epitopes have been identified. 15 Moreover, LMP1 displays heterogeneity between viral strains, 16 and CTLs raised against B cell (B95-8 prototype) derived LMP1 may not recognize LMP1 tumor variants. 17 BARF0 is a protein expressed from the BamHI A rightward transcript. Attempts to identify BARF0-specific CTLs have produced lymphocytes that recognized target cells expressing BARF0 at high levels but failed to recognize the antigen expressed at lower levels in LCLs. 18 LMP2A epitopes were shown to be conserved among Hodgkin's lymphoma biopsy samples displaying little heterogeneity between viral strains. 19,20 Also, most donors have a low but measurable frequency of circulating LMP2A-specific CTLs that can be activated and expanded in vitro. 14 Hence, LMP2A may be the protein of choice to be targeted by CTLs in patients with Hodgkin's lymphoma.To stimulate LMP2A-specific CTLs, LMP2A peptide-pulsed DCs have been successfully used, but this approach is limited to known MHC-restricted peptides. 21,22 A more promising strategy is the production of CTLs by genetically modified DCs that direct the CTL response to virally transduced genes. [23][24][25] This approach allows expression of t...

Epstein-Barr Virus Latent Membrane Protein LMP-2A Is Sufficient for Transactivation of the Human Endogenous Retrovirus HERV-K18 Superantigen

“…We did this by infecting BL-41 cells with an adenoviral vector containing LMP-2A driven by the cytomegalovirus (CMV) promoter, AdLMP2 (19). In order to test whether LMP-1 can transactivate HERV-K18, we created an adenoviral vector containing (10) and UpGFP, which carry the enhanced green fluorescence protein (EGFP) gene driven by the CMV or the ubiquitin promoter.…”

Virally targeted therapies for EBV-associated malignancies

“…Clinical trials of EBV-CTL therapy for such tumors are ongoing Chua et al, 2001). CTL responses to LMP-1/2 epitopes can be generated in vitro (Meij et al, 2002), and several groups have addressed in vitro the presumed requirement to enhance CTL response to LMP-2 and/or LMP-1 (Gahn et al, 2001;Su et al, 2001). Nevertheless, the fact that such tumors can develop in hosts with apparently intact CTL function suggests that tumor paracrine effects, such as secreted TGF-b and IL-10, may limit the function of EBV-specific CTLs.…”

Computational Prediction and Identification of Epstein-Barr Virus Latent Membrane Protein 2A Antigen-Specific CD8+ T-Cell Epitopes

“…Recently, there have been many attempts to use genetransfected DCs to sensitize T cells to recognize target cells expressing relative antigen in research of EBV-relative malignancies (23)(24)(25)(26). In a variety of vectors, vaccinia virus has more recently been used as a versatile eukaryotic expression vector and is important in tumor gene transfecting.…”