title: A role for IL-18 in neutrophil activation.
abstract: IL-18 expression and functional activity has been identified in several autoimmune and infectious diseases. To clarify the potential role of IL-18 during early innate immune responses, we have explored the capacity of IL-18 to activate neutrophils. Human peripheral blood-derived neutrophils constitutively expressed IL-18R (alpha and beta) commensurate with the capacity to rapidly respond to IL-18. IL-18 induced cytokine and chemokine release from neutrophils that was protein synthesis dependent, up-regulated CD11b expression, induced granule release, and enhanced the respiratory burst following exposure to fMLP, but had no effect upon the rate of neutrophil apoptosis. The capacity to release cytokine and chemokine was significantly enhanced in neutrophils derived from rheumatoid arthritis synovial fluid, indicating differential responsiveness to IL-18 dependent upon prior neutrophil activation in vivo. Finally, IL-18 administration promoted neutrophil accumulation in vivo, whereas IL-18 neutralization suppressed the severity of footpad inflammation following carrageenan injection. The latter was accompanied by reduction in tissue myeloperoxidase expression and suppressed local TNF-alpha production. Together, these data define a novel role for IL-18 in activating neutrophils and thereby promoting early innate immune responses.
authors.affiliation: Department of Immunology and Bacteriology, Western Infirmary, University of Glasgow, Glasgow, United Kingdom.
authors.forename: B P
authors.initials: BP
authors.lastname: Leung
authors.forename: S
authors.initials: S
authors.lastname: Culshaw
authors.forename: J A
authors.initials: JA
authors.lastname: Gracie
authors.forename: D
authors.initials: D
authors.lastname: Hunter
authors.forename: C A
authors.initials: CA
authors.lastname: Canetti
authors.forename: C
authors.initials: C
authors.lastname: Campbell
authors.forename: F
authors.initials: F
authors.lastname: Cunha
authors.forename: F Y
authors.initials: FY
authors.lastname: Liew
authors.forename: I B
authors.initials: IB
authors.lastname: McInnes
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001172:Arthritis, Rheumatoid / Q000276:immunology; D001483:Base Sequence; D015550:Cell Degranulation / Q000187:drug effects; D016207:Cytokines / Q000096:biosynthesis / Q000235:genetics; D017931:DNA Primers / Q000235:genetics; D006801:Humans; D066298:In Vitro Techniques; D007249:Inflammation / Q000209:etiology / Q000276:immunology / Q000517:prevention & control; D020382:Interleukin-18 / Q000276:immunology* / Q000494:pharmacology / Q000502:physiology; D053727:Interleukin-18 Receptor alpha Subunit; D016177:Macrophage-1 Antigen / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D008809:Mice, Inbred C3H; D009504:Neutrophils / Q000166:cytology / Q000187:drug effects / Q000276:immunology* / Q000502:physiology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D018123:Receptors, Interleukin / Q000235:genetics; D053724:Receptors, Interleukin-18; D016897:Respiratory Burst / Q000187:drug effects; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D016207:Cytokines; D017931:DNA Primers; C508572:IL18R1 protein, human; C508573:Il18r1 protein, mouse; D020382:Interleukin-18; D053727:Interleukin-18 Receptor alpha Subunit; D016177:Macrophage-1 Antigen; D012333:RNA, Messenger; D018123:Receptors, Interleukin; D053724:Receptors, Interleukin-18