title: Inhibitory effect of extracellular purine nucleotide and nucleoside concentrations on T cell proliferation.
abstract: The release of nucleic acids and derivatives after tissue-injury may affect cellular immune-response. We studied the impact of extracellular ribo-, desoxyribonucleotides and nucleosides on T-cell immunity. Peripheral-blood-mononuclear-cells (PBMCs) or isolated CD3+T-cells obtained from 6 healthy donors were stimulated via CD3/CD28 Dynabeads or dendritic cells (DCs) in the presence or absence of pyrimidine-, purine-nucleotides and -nucleosides (range 2-200µM). Addition of deoxy-, guanosine-triphosphate (dGTP, GTP) and guanosine resulted concentration dependent in a complete, adenosine-triphosphate (ATP) in a partial inhibition of the induced T-cell-proliferation. Deoxyadenosine-triphosphate (dATP), adenosine and the pyrimidine-ribo- and -deoxyribonucleotides displayed no inhibitory capacity. Inhibitory effects of dGTP and GTP, but not of guanosine and ATP were culture-media-dependent and could be almost abrogated by use of the serum-free lymphocyte-culture-media X-Vivo15 instead of RPMI1640 with standard-supplementation. In contrast to RPMI1640, X-Vivo15 resulted in a significant down-regulation of the cell-surface-located ectonucleotidases CD39 (Ecto-Apyrase) and CD73 (Ecto-5'-Nucleotidase), critical for the extracellular nucleotides-hydrolysis to nucleosides, explaining the loss of inhibition mediated by dGTP and GTP, but not Guanosine. In line with previous findings ATP was found to exert immunosuppressive effects on T-cell-proliferation. Purine-nucleotides, dGTP and GTP displayed a higher inhibitory capacity, but seem to be strictly dependent on the microenvironmental conditions modulating the responsiveness of the respective T-lymphocytes. Further evaluation of experimental and respective clinical settings should anticipate these findings.
authors.affiliation: Department of Medicine III and Transfusion Medicine, University Hospital Grosshadern, Ludwig-Maximilians-University, Munich, Germany.
authors.forename: Monica
authors.initials: M
authors.lastname: Weiler
authors.affiliation: Helmholtz Center Munich; German Research Center for Environmental Health, Munich, Germany.
authors.forename: Helga
authors.initials: H
authors.lastname: Schmetzer
authors.affiliation: Helmholtz Center Munich; German Research Center for Environmental Health, Munich, Germany; Department of Medicine III and Transfusion Medicine, University Hospital Grosshadern, Ludwig-Maximilians-University, Munich, Germany.
authors.forename: Marion
authors.initials: M
authors.lastname: Braeu
authors.affiliation: Helmholtz Center Munich; German Research Center for Environmental Health, Munich, Germany; Department of Medicine III and Transfusion Medicine, University Hospital Grosshadern, Ludwig-Maximilians-University, Munich, Germany.
authors.forename: Raymund
authors.initials: R
authors.lastname: Buhmann
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology; D015703:Antigens, CD / Q000378:metabolism; D002452:Cell Count; D049109:Cell Proliferation / Q000187:drug effects; D003713:Dendritic Cells / Q000166:cytology / Q000187:drug effects; D005110:Extracellular Space / Q000737:chemistry*; D005434:Flow Cytometry; D006160:Guanosine Triphosphate / Q000494:pharmacology; D006801:Humans; D007166:Immunosuppressive Agents / Q000494:pharmacology; D019169:Jurkat Cells; D007959:Lymphocyte Culture Test, Mixed; D009173:Mycophenolic Acid / Q000494:pharmacology; D009705:Nucleosides / Q000494:pharmacology*; D011685:Purine Nucleotides / Q000494:pharmacology*; D013601:T-Lymphocytes / Q000166:cytology* / Q000187:drug effects
chemical_list: D015703:Antigens, CD; D007166:Immunosuppressive Agents; D009705:Nucleosides; D011685:Purine Nucleotides; D006160:Guanosine Triphosphate; D000255:Adenosine Triphosphate; D009173:Mycophenolic Acid
keywords: Extracellular milieu; Nucleosides; Nucleotides; T cell proliferation