title: Antigen-activated human T lymphocytes express cell-surface NKG2D ligands via an ATM/ATR-dependent mechanism and become susceptible to autologous NK- cell lysis.
abstract: Recent evidence indicates that natural killer (NK) cells can negatively regulate T-cell responses, but the mechanisms behind this phenomenon as a consequence of NK-T-cell interactions are poorly understood. We studied the interaction between the NKG2D receptor and its ligands (NKG2DLs), and asked whether T cells expressed NKG2DLs in response to superantigen, alloantigen, or a specific antigenic peptide, and if this rendered them susceptible to NK lysis. As evaluated by FACS, the major histocompatibility complex (MHC) class I chain-related protein A (MICA) was the ligand expressed earlier on both CD4(+) and CD8(+) T cells in 90% of the donors tested, while UL16-binding protein-1 (ULBP)1, ULBP2, and ULBP3 were induced at later times in 55%-75% of the donors. By carboxyfluorescein diacetate succinimidyl ester (CFSE) labeling, we observed that NKG2DLs were expressed mainly on T cells that had gone through at least one division. Real-time reverse-transcription polymerase chain reaction confirmed the expression of all NKG2DLs, except ULBP4. In addition, T-cell activation stimulated phosphorylation of ataxia-telangiectasia mutated (ATM), a kinase required for NKG2DLs expression after DNA damage, and ATM/Rad3-related kinase (ATR) inhibitors blocked MICA induction on T cells with a mechanism involving NF-kappaB. Finally, we demonstrated that activated T cells became susceptible to autologous NK lysis via NKG2D/NKG2DLs interaction and granule exocytosis, suggesting that NK lysis of T lymphocytes via NKG2D may be an additional mechanism to limit T-cell responses.
authors.affiliation: Department of Experimental Medicine, Istituto Pasteur-Fondazione Cenci Bolognetti, University La Sapienza, Rome, Italy.
authors.forename: Cristina
authors.initials: C
authors.lastname: Cerboni
authors.forename: Alessandra
authors.initials: A
authors.lastname: Zingoni
authors.forename: Marco
authors.initials: M
authors.lastname: Cippitelli
authors.forename: Mario
authors.initials: M
authors.lastname: Piccoli
authors.forename: Luigi
authors.initials: L
authors.lastname: Frati
authors.forename: Angela
authors.initials: A
authors.lastname: Santoni
mesh_terms: D001329:Autolysis / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology; D002470:Cell Survival; D005434:Flow Cytometry; D058851:GPI-Linked Proteins; D005786:Gene Expression Regulation; D015395:Histocompatibility Antigens Class I / Q000276:immunology; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D007519:Isoantigens / Q000276:immunology*; D007694:Killer Cells, Natural / Q000166:cytology / Q000276:immunology*; D007963:Leukocytes, Mononuclear / Q000276:immunology; D008213:Lymphocyte Activation; D016328:NF-kappa B / Q000235:genetics; D016133:Polymerase Chain Reaction; D012313:RNA / Q000235:genetics; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D058851:GPI-Linked Proteins; D015395:Histocompatibility Antigens Class I; D036341:Intercellular Signaling Peptides and Proteins; D007519:Isoantigens; D016328:NF-kappa B; C423230:ULBP2 protein, human; D012313:RNA