title: Pertussis toxin pretreatment reveals differential effects of adenosine analogs on IgE-dependent histamine and peptidoleukotriene release from RBL-2H3 cells.
abstract: The effects of adenosine (A) and the nonmetabolizable adenosine analogs, N-ethylcarboxamidoadenosine (NECA), L-phenylisopropyladenosine (L-PIA), D-PIA and 2-chloroadenosine (2CHA) were examined on the IgE-dependent mediator release from RBL-2H3 cells, a model for mast-cell function. Adenosine and the adenosine analogs failed to influence mediator release from cells, previously sensitized with monoclonal anti-TNP mouse immunoglobulin E (anti-TNP IgE), when added alone. When added prior to conjugated trinitrophenol-ovalbumin (TNP-OVA), adenosine and the adenosine analogs (10(-8)-10(-4) M) significantly potentiated the release of both histamine (marker for degranulation) and peptidoleukotrienes (LT) (marker for de novo synthesized mediators). The effects were concentration-dependent with the potency order being L-PIA greater than NECA greater than A greater than D-PIA, 2CHA. The stimulatory effect on both histamine and LT release were reversed by prior treatment of the cells with pertussis toxin but not by the purinoceptor antagonists, theophylline and 8-phenyltheophylline, nor adenosine uptake blockers. At higher concentrations (above 10(-5) M), adenosine and adenosine analogs were also inhibitory on LT but not on histamine release. This inhibition was more evident on pertussis-toxin-treated cells in which there was no effect of adenosine or adenosine analogs on histamine release, but a concentration-dependent inhibition of IgE-dependent LT release. These findings demonstrate that adenosine analogs have two distinct mechanisms on mediator release from RBL-2H3 cells; a stimulatory effect on both histamine and LT release, mediated via a pertussis-toxin-sensitive G protein and an inhibitory effect on LT release via a pertussis-toxin-insensitive pathway. An abstract of this work has been published.
authors.affiliation: Department of Pharmacology, Hoffmann-La Roche, Nutley, NJ 07110.
authors.forename: A M
authors.initials: AM
authors.lastname: Gilfillan
authors.forename: G A
authors.initials: GA
authors.lastname: Wiggan
authors.forename: A F
authors.initials: AF
authors.lastname: Welton
mesh_terms: D000241:Adenosine / Q000031:analogs & derivatives / Q000494:pharmacology*; D019830:Adenosine-5'-(N-ethylcarboxamide); D000818:Animals; D003994:Bucladesine / Q000494:pharmacology; D002460:Cell Line; D006632:Histamine / Q000276:immunology / Q000378:metabolism*; D007073:Immunoglobulin E / Q000276:immunology; D007700:Kinetics; D015289:Leukotrienes / Q000378:metabolism*; D008407:Mast Cells / Q000187:drug effects / Q000276:immunology / Q000378:metabolism; D010455:Peptides / Q000378:metabolism*; D037342:Pertussis Toxin; D013806:Theophylline / Q000031:analogs & derivatives / Q000494:pharmacology; D010566:Virulence Factors, Bordetella / Q000494:pharmacology*
chemical_list: D015289:Leukotrienes; D010455:Peptides; D010566:Virulence Factors, Bordetella; D019830:Adenosine-5'-(N-ethylcarboxamide); D007073:Immunoglobulin E; D003994:Bucladesine; D006632:Histamine; D013806:Theophylline; C028322:8-phenyltheophylline; D037342:Pertussis Toxin; D000241:Adenosine