title: Adenosine inhibits activation-induced T cell expression of CD2 and CD28 co-stimulatory molecules: role of interleukin-2 and cyclic AMP signaling pathways.
abstract: Adenosine is an immunosuppressive molecule that is associated with the microenvironment of solid tumors. Mouse T cells activated with anti-CD3 antibody in the presence of adenosine with or without coformycin (to prevent adenosine breakdown by adenosine deaminase) exhibited decreased tyrosine phosphorylation of some intracellular proteins and were inhibited in their ability to proliferate and synthesize interleukin (IL)-2. In addition, adenosine interfered with activation-induced expression of the co-stimulatory molecules CD2 and CD28. Activation-induced CD2 and CD28 expression was also diminished when T cells were activated in the presence of anti-IL-2 and anti-CD25 antibodies to neutralize IL-2 bioactivity. Collectively, these data suggest that CD2 and CD28 up-regulation following T cell activation is IL-2-dependent; and that adenosine inhibits activation-induced T cell expression of CD2 and CD28 by interfering with IL-2-dependent signaling. The inhibitory effect of adenosine on activation-induced CD2 and CD28 expression could not be attributed to cyclic AMP (cAMP) accumulation resulting from the stimulation of adenylyl cyclase-coupled adenosine receptors, even though cAMP at concentrations much higher than those generated following adenosine stimulation was inhibitory for both CD2 and CD28 expression. We conclude that adenosine interferes with IL-2-dependent T cell expression of co-stimulatory molecules via a mechanism that does not involve the accumulation of intracellular cAMP.
authors.affiliation: Department of Microbiology & Immunology, Faculty of Medicine, Sir Charles Tupper Medical Building, Dalhousie University, Halifax, Nova Scotia B3H 1X5, Canada.
authors.forename: Jared J
authors.initials: JJ
authors.lastname: Butler
authors.forename: Jamie S
authors.initials: JS
authors.lastname: Mader
authors.forename: Carrie L
authors.initials: CL
authors.lastname: Watson
authors.forename: Hong
authors.initials: H
authors.lastname: Zhang
authors.forename: Jonathan
authors.initials: J
authors.lastname: Blay
authors.forename: David W
authors.initials: DW
authors.lastname: Hoskin
mesh_terms: D000241:Adenosine / Q000031:analogs & derivatives* / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology / Q000494:pharmacology; D018801:CD2 Antigens / Q000096:biosynthesis*; D018106:CD28 Antigens / Q000096:biosynthesis*; D017252:CD3 Complex / Q000276:immunology; D002110:Caffeine / Q000031:analogs & derivatives* / Q000494:pharmacology; D002453:Cell Cycle / Q000187:drug effects; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism / Q000502:physiology*; D005260:Female; D005415:Flavins / Q000494:pharmacology; D007376:Interleukin-2 / Q000276:immunology / Q000378:metabolism / Q000502:physiology*; D008213:Lymphocyte Activation / Q000187:drug effects / Q000502:physiology; D051379:Mice; D008810:Mice, Inbred C57BL; D010627:Phenethylamines / Q000494:pharmacology; D015375:Receptors, Interleukin-2 / Q000276:immunology; D018047:Receptors, Purinergic P1 / Q000187:drug effects / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D013601:T-Lymphocytes / Q000166:cytology / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D014443:Tyrosine / Q000378:metabolism
chemical_list: D000911:Antibodies, Monoclonal; D018801:CD2 Antigens; D018106:CD28 Antigens; D017252:CD3 Complex; D005415:Flavins; D007376:Interleukin-2; D010627:Phenethylamines; D015375:Receptors, Interleukin-2; D018047:Receptors, Purinergic P1; C061282:2-(4-(2-carboxyethyl)phenethylamino)-5'-N-ethylcarboxamidoadenosine; C081320:8-(3-chlorostyryl)caffeine; D005576:Colforsin; D002110:Caffeine; D014443:Tyrosine; C008173:isoalloxazine; D000242:Cyclic AMP; D000241:Adenosine