Functional Characterization of EBV-Encoded Nuclear Antigen 1–Specific CD4+ Helper and Regulatory T Cells Elicited byIn vitroPeptide Stimulation

Abstract

CD4+ helper and regulatory T (Treg) cells play important but opposing roles in regulating host immune responses against cancer and other diseases. However, very little is known about the antigen specificity of CD4 + Treg cells. Here we describe the generation of a panel of EBV-encoded nuclear antigen 1 (EBNA1)-specific CD4 + T-cell lines and clones that recognize naturally processed EBNA1-P 607-619 and -P 561-573 peptides in the context of HLA-DQ2 and HLA-DR11, -DR12, and -DR13 molecules, respectively. Phenotypic and functional analyses of these CD4 + T cells revealed that they represent EBNA1-specific CD4 + T helper as well as Treg cells. CD4 + Treg cells do not secrete interleukin (IL)-10 and transforming growth factor h cytokines but express CD25, the glucocorticoid-induced tumor necrosis factor receptor-related protein (GITR), and Forkhead Box P3 (Foxp3), and are capable of suppressing the proliferative responses of naïve CD4 + and CD8 + T cells to stimulation with mitogenic anti-CD3 antibody. The suppressive activity of these CD4 + Treg cells is mediated via cell-cell contact or in part by a cytokine-dependent manner. Importantly, these Treg cells suppress IL-2 secretion by CD4 + effector T cells specific for either EBNA1 or a melanoma antigen, suggesting that these CD4 + Treg cells induce immune suppression. These observations suggest that the success of peptide-based vaccines against EBV-associated cancer and other diseases may likely depend upon our ability to identify antigens/ peptides that preferentially activate helper T cells and/or to design strategies to regulate the balance between CD4 + helper and Treg cells. (Cancer Res 2005; 65(4): 1577-86)

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

“…Both EBNA1 and LMP1 are known to encode for antigenic peptides that expand IL‐10‐secreting regulatory CD4 + T cells 38, 39. However, no correlations were found between the EBV latency II genes and expression of either CD4 or the regulatory T cell markers IL‐10, lymphocyte‐activation gene 3 (LAG3) and forkead box protein 3 (FoxP3) [ P  = not significant (n.s.…”

Potent Dendritic Cell Vaccine Loaded with Latent Membrane Protein 2A (LMP2A)

“…This implies that these malignancies are able to develop despite the presence of circulating tumor-specific T cells. Secretion of immunosuppressive chemokines and cytokines and the presence of regulatory T cells at the tumor site may contribute to this escape from immune surveillance (21). Immunotherapeutic strategies that enhance the LMP2-specific immune response may overcome this immunosuppressive environment.…”

“…In addition to its potential role in the pathogenesis of NPC, EBV also provides a possible target for immunotherapy of NPC, since a limited number of viral genes are expressed in the neoplastic cells, including EBNA1, LMP1 and LMP2 (16,17,19,20). Although EBNA1 appears to be an immunogen for reactivating EBNA1-specific CD4 + T cell clones, the majority of such clones fail to recognize lymphoblastoid B cell lines (LCL) target cells (21). LMP1 has been confirmed to be consistent with its ability to transform rodent fibroblasts, and its target epitopes recognized by virus-specific CTL are easy to mutate (22).…”

Functional Analysis of Birch Pollen Allergen Bet v 1-Specific Regulatory T Cells

“…7). Recently, Voo et al (28) reported that EBV-encoded nuclear Ag 1 peptide-reactive Treg cells required cell-cell contact or an unidentified soluble factor (not IL-10 nor TGF-␤) to exert their suppressive activity.…”

“…These Treg cells express several characteristic markers such as CD25, glucocorticoid-induced TNF receptor (GITR), and the Forkhead Box P3 (Foxp3) transcription factor (22)(23)(24)(25)(26)(27)(28). Although Foxp3 may be a relatively specific intracellular marker compared with other cell surface molecules, a definitive maker for Treg cells has not been found yet.…”