title: Alloreactivity across HLA barriers is mediated by both naïve and antigen-experienced T cells.
abstract: T cell responses to allogeneic targets arise predominantly from the naïve pool. However, in humans, the risk of graft-versus-host disease is increased if the donor has circulating T cells recognizing multiple persistent DNA viruses, suggesting that memory T cells also contribute to the alloresponse. To examine HLA alloreactivity, we used flow cytometry-based proliferation and cytokine production assays. We identified the clonal identity of virus-specific T cells cross-reacting with HLA-disparate targets by sequencing the T cell receptor β chains in virus-specific T cell lines restimulated with cognate and HLA-disparate targets and sorting these chains according to cytokine response. We confirmed that naïve T cells from cord blood and adult individuals responded to HLA-mismatched target cells. In addition, in adults, we identified memory T cells responding by cytokine release to HLA-mismatched targets both in direct assays and after 8 days of culture with allogeneic stimulator cells. Epstein-Barr virus-specific and cytomegalovirus-specific T cells, tested against a panel of 30 T cell antigen-presenting cells with a broad coverage of the most prominent HLA types, displayed specificity for certain mismatched HLA alleles. Sequencing of the T cell receptor β chain demonstrated a clonotypic identity of cells that responded to both viral and allogeneic stimulation. These findings show conclusively that alloresponses in humans are not confined to the naïve T cell subset, and that memory viral antigen-specific T cells can cross-react with specific mismatched HLA-peptide complexes not presenting with cytomegalovirus or Epstein-Barr virus peptides.
authors.affiliation: Hematology Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892-1202, USA. melenhoj@nhlbi.nih.gov
authors.forename: J Joseph
authors.initials: JJ
authors.lastname: Melenhorst
authors.forename: Phillip
authors.initials: P
authors.lastname: Scheinberg
authors.forename: Ann
authors.initials: A
authors.lastname: Williams
authors.forename: David R
authors.initials: DR
authors.lastname: Ambrozak
authors.forename: Keyvan
authors.initials: K
authors.lastname: Keyvanfar
authors.forename: Melody
authors.initials: M
authors.lastname: Smith
authors.forename: J Philip
authors.initials: JP
authors.lastname: McCoy
authors.forename: Nancy F
authors.initials: NF
authors.lastname: Hensel
authors.forename: Daniel C
authors.initials: DC
authors.lastname: Douek
authors.forename: A John
authors.initials: AJ
authors.lastname: Barrett
mesh_terms: D000328:Adult; D000938:Antigen-Presenting Cells / Q000276:immunology; D000956:Antigens, Viral / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D003429:Cross Reactions; D016207:Cytokines / Q000096:biosynthesis*; D003587:Cytomegalovirus / Q000276:immunology; D005260:Female; D005312:Fetal Blood / Q000276:immunology; D005434:Flow Cytometry; D006086:Graft vs Host Disease / Q000276:immunology; D006680:HLA Antigens / Q000276:immunology; D004854:Herpesvirus 4, Human / Q000276:immunology; D006801:Humans; D007156:Immunologic Memory; D011247:Pregnancy; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000737:chemistry / Q000276:immunology*; D017422:Sequence Analysis, DNA
chemical_list: D000956:Antigens, Viral; D016207:Cytokines; D006680:HLA Antigens; D016693:Receptors, Antigen, T-Cell, alpha-beta