title: Purine metabolites suppress proliferation of human NK cells through a lineage-specific purine receptor.
abstract: NK cell proliferation is suppressed in some patients with cancer by unknown mechanisms. Because purine metabolites released into the extracellular space during cell lysis may affect cell function, we hypothesized that these metabolites could serve as feedback regulators of NK cell proliferation. Sorted NK (CD56+/CD3-) cells were incubated with IL-2 (1000 U/ml) in a 4-day thymidine uptake assay with or without 10-10,000 microM of nucleotides. Adenine nucleotides inhibited NK cell proliferation, with ATP = ADP > 5'-adenylylimidodiphosphate > AMP = adenosine; ADP-ribose and nicotinamide adenine dinucleotide, but not nicotinamide or UTP, caused a dose-dependent suppression of thymidine uptake. A total of 100 microM ATP, a concentration that induced a maximal (80%) inhibition of thymidine uptake, did not inhibit cytotoxic activity against K562 targets. Because NK cells retained the ability to lyse K562 targets 4 days after exposure to 500 microM ATP or 1000 microM adenosine, inhibition of thymidine uptake was not due to cell death. Incubation of NK cells with dibutyryl cAMP and forskolin also suppressed thymidine uptake. Cholera toxin and pertussis toxin suppressed NK cell proliferation. Pertussis toxin did not block the adenine nucleotide effects. Further, ATP, but not adenosine or other nucleotides, markedly increased intracellular cAMP in a dose-dependent manner. The ATP-induced increase in cAMP was specific to cytolytic cells, because CD19+ B cells and CD4+ T cells did not increase their intracellular cAMP. These studies demonstrate that NK proliferation is regulated through purine receptors by adenine nucleotides, which may play a role in decreased NK cell activity. The response to adenine nucleotides is lineage-specific.
authors.affiliation: Department of Medicine, University of Minnesota Cancer Center, Minneapolis 55455, USA. mille011@tc.umn.edu
authors.forename: J S
authors.initials: JS
authors.lastname: Miller
authors.forename: T
authors.initials: T
authors.lastname: Cervenka
authors.forename: J
authors.initials: J
authors.lastname: Lund
authors.forename: I J
authors.initials: IJ
authors.lastname: Okazaki
authors.forename: J
authors.initials: J
authors.lastname: Moss
mesh_terms: D000244:Adenosine Diphosphate / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000494:pharmacology; D001402:B-Lymphocytes / Q000166:cytology / Q000276:immunology; D019002:CD56 Antigen / Q000096:biosynthesis; D019070:Cell Lineage / Q000276:immunology; D002469:Cell Separation; D000242:Cyclic AMP / Q000378:metabolism; D016207:Cytokines / Q000096:biosynthesis; D003602:Cytotoxicity, Immunologic / Q000187:drug effects / Q000276:immunology; D006131:Growth Inhibitors / Q000494:pharmacology* / Q000633:toxicity; D006801:Humans; D007166:Immunosuppressive Agents / Q000494:pharmacology* / Q000633:toxicity; D007424:Intracellular Fluid / Q000378:metabolism; D020014:K562 Cells; D007694:Killer Cells, Natural / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D008213:Lymphocyte Activation / Q000187:drug effects / Q000276:immunology*; D011685:Purine Nucleotides / Q000378:metabolism / Q000494:pharmacology* / Q000633:toxicity; D018047:Receptors, Purinergic P1 / Q000502:physiology*; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology
chemical_list: D019002:CD56 Antigen; D016207:Cytokines; D006131:Growth Inhibitors; D007166:Immunosuppressive Agents; D011685:Purine Nucleotides; D018047:Receptors, Purinergic P1; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D000242:Cyclic AMP