|
|||||||||
|
|
|
|
|
|
|
|
|
|
|
Blood, 15 September 2008, Vol. 112, No. 6, pp. 2589-2590.
CORRESPONDENCE A mechanism for the HLA-A*01–associated risk for EBV+ Hodgkin lymphoma and infectious mononucleosisTo the editor:Expression of the common class I human leukocyte antigen (HLA) A*01 has recently been shown to increase the risk of developing Epstein-Barr virus (EBV)–positive Hodgkin lymphoma (HL).1 Furthermore, genetic markers closely linked to the HLA-A*01 allele were also shown to be associated with development of acute infectious mononucleosis (IM) upon primary EBV infection.2 It is not surprising that these 2 EBV-associated diseases share the same genetic predisposition because a previous history of IM is a significant risk factor for EBV-associated HL.3 Because HLA-class-I molecules present viral peptides for recognition by CD8+ T cells, and because this T-cell subset is known to play a critical role in the control of EBV infection,4 we investigated the hypothesis that the EBV-specific T-cell response restricted through HLA-A*01 is relatively weak, thereby providing a possible mechanism to explain the link between HLA-A*01 expression and these EBV-associated diseases. Peripheral blood mononuclear cells from 8 HLA-A*01+, EBV-seropositive healthy subjects were stimulated with an irradiated autologous lymphoblastoid cell line (LCL) to expand the EBV-specific T-cell population. The relative strength of the EBV-specific CD8+ T-cell response, restricted through individual HLA alleles, was then assessed using intracellular cytokine staining (ICS) after a brief period of stimulation with the mutant HLA-class-I–negative 721.221 LCLs5 that had been transfected to expressed only HLA-A*01 or other HLA-class-I alleles. Figure 1A shows representative flow cytometric data for one donor (Donor B19: HLA-A*01, A*03, B*08, B*44), which clearly demonstrates that the EBV-specific T-cell response restricted through HLA-A*01 is negligible, while the response restricted through another self-HLA-allele B*08 is very strong (8.18% of CD8+ cells). As expected, the 721.221 LCLs transfected to express the allogeneic HLA-A*02 allele failed to stimulate a significant response. Data from the other 7 HLA-A*01+ donors are summarized in Figure 1B. Although the overall strength of the EBV-specific CD8+ T-cell response varied between the donors, the data confirmed that the EBV-specific T-cell response restricted through HLA-A*01 is negligible, while responses restricted through at least one other self-HLA allele were significant.
As a positive control, to confirm that the HLA-A*01–transfected 721.221 cell line expressed this HLA molecule on the cell surface, a T-cell clone specific for the HLA-A*01–binding human cytomegalovirus epitope YSEHPTFTSQY6 was tested for recognition of 721.221-HLA-A*01 cells that had been preincubated with the YSEHPTFTSQY synthetic peptide and washed extensively. As shown in Figure 1C, these peptide-treated cells stimulated 71.5% of the T cells, confirming expression of functional HLA-A*01 molecules on the surface of the 721.221-HLA-A*01 cells. These data provide strong evidence that HLA-A*01 fails to present highly immunogenic peptides from the EBV latent antigens expressed by LCLs. Although we are not aware of any previous studies that have specifically examined the HLA-A*01-restricted, EBV-specific response, it is notable that no T-cell epitopes that bind to this HLA allele have yet been mapped to any EBV antigens. Thus T-cell control over the proliferation of EBV+ B cells and the malignant, EBV+ Hodgkin Reed Sternberg cells may be relatively inefficient in HLA-A*01+ individuals, particularly those homozygous for this allele, thereby contributing to an increased risk of acute infectious mononucleosis and EBV+ Hodgkin lymphoma. Authorship Contribution: R.M.B. performed research, analyzed data, and wrote the paper; and S.R.B. designed research, analyzed data, and wrote the paper. Conflict-of-interest disclosure: The authors declare no competing financial interests. Correspondence: Scott Burrows, Queensland Institute of Medical Research and School of Medicine, University of Queensland, Herston, Brisbane, Australia; e-mail: scott.burrows{at}qimr.edu.au.
References
  CiteULike  Connotea  Del.icio.us  Digg  Reddit  Technorati What's this?
Related Article in Blood Online:
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
 |
 |
 |
|||||||
 |
 |
 |
 |
 |
 |
 |
 |
||
| Copyright © 2008 by American Society of Hematology Online ISSN: 1528-0020 | |||||||||
–producing T cells after overnight incubation at 37°C in medium supplemented with brefeldin A (BD Pharmingen) and with the HLA-class-I–negative 721.221 cell line that had been transfected to express a single HLA-class-I allele. These cell lines were established as follows: cDNA for each HLA allele was amplified using sequence-specific primers and cloned into the expression vector pEGFP-N1 (Clontech, Palo Alto, CA), which contains a green fluorescent protein (GFP) tag and an antibiotic resistance gene to allow for positive selection. The HLA-EGFP-N1 expression constructs were transfected into 721.221 cells using the Bio-Rad Gene Pulser, and transfectants were cultured in the presence of G418 antibiotic (800 µg/mL) for 3 weeks. GFP-positive cells were sorted using a FACSVantage, and the purified cells were maintained in the presence of G418 (800 µg/mL). HLA class I expression on the transfectants was confirmed using an anti–HLA-class-I monoclonal antibody (W6/32) and flow cytometry. The antibody staining for the ICS flow cytometry analysis involved incubation of the responder-stimulator cell mixtures at 4°C for 30 minutes with peridinin chlorophyll protein–conjugated anti-CD8, and allophycocyanin-conjugated anti-CD3. Cells were then fixed and permeabilized with Cytofix/Cytoperm (BD Pharmingen) at 4°C for 20 minutes, washed and incubated with phycoerythrin (PE)–conjugated anti-interferon-