Identification of Epstein-Barr virus-specific CD8+ T lymphocytes in the circulation of pediatric transplant recipients.
BACKGROUND
Pediatric transplant recipients are at increased risk for Epstein Barr virus (EBV)-related B cell lymphomas. In healthy individuals, the expansion of EBV-infected B cells is controlled by CD8+ cytotoxic T cells. However, immunosuppressive therapy may compromise antiviral immunity. We identified and determined the frequency of EBV-specific T cells in the peripheral blood of pediatric transplant recipients.


METHODS
HLA-B*0801 and HLA-A*0201 tetramers folded with immunodominant EBV peptides were used to detect EBV-specific CD8+ T cells by flow cytometry in peripheral blood mononuclear cells from 24 pediatric liver and kidney transplant recipients. The expression of CD38 and CD45RO on EBV-specific, tetramer-binding cells was also examined in a subset of patients by immunofluorescent staining and flow cytometry.


RESULTS
Tetramer-binding CD8+ T cells were identified in 21 of 24 transplant recipients. EBV-specific CD8+ T cells were detected as early as 4 weeks after transplant in EBV seronegative patients receiving an organ from an EBV seropositive donor. The frequencies (expressed as a percentage of the CD8+ T cells) of the tetramer-binding cells were HLA-B8-RAKFKQLL (BZLF1 lytic antigen peptide) tetramer, range=0.96 to 3.94%; HLA-B8-FLRGRAYGL (EBNA3A latent antigen peptide) tetramer, range=0.03 to 0.59%; and HLA-A2-GLCTLVAML (BMLF1 lytic antigen peptide) tetramer, range=0.06 to 0.76%. The majority of tetramer reactive cells displayed an activated/memory phenotype.


CONCLUSIONS
Pediatric transplant recipients receiving immunosuppression can generate EBV-specific CD8+ T cells. Phenotypic and functional analysis of tetramer cells may prove useful in defining and monitoring EBV infection in the posttransplant patient.
D036541:ADP-ribosyl Cyclase; D051997:ADP-ribosyl Cyclase 1; D000293:Adolescent; D015703:Antigens, CD; D000943:Antigens, Differentiation / Q000032:analysis; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D002648:Child; D002675:Child, Preschool; D015789:HLA-A2 Antigen / Q000737:chemistry; D015795:HLA-B8 Antigen / Q000737:chemistry; D004854:Herpesvirus 4, Human / Q000276:immunology*; D006801:Humans; D016130:Immunophenotyping; D007223:Infant; D016030:Kidney Transplantation / Q000009:adverse effects*; D016031:Liver Transplantation / Q000009:adverse effects*; D016393:Lymphoma, B-Cell / Q000175:diagnosis*; D008562:Membrane Glycoproteins; D009244:NAD+ Nucleosidase / Q000032:analysis
D015703:Antigens, CD; D000943:Antigens, Differentiation; D015789:HLA-A2 Antigen; D015795:HLA-B8 Antigen; D008562:Membrane Glycoproteins; D036541:ADP-ribosyl Cyclase; C498154:CD38 protein, human; D009244:NAD+ Nucleosidase; D051997:ADP-ribosyl Cyclase 1