title: An absolute requirement for STAT4 and a role for IFN-gamma as an amplifying factor in IL-12 induction of the functional IL-18 receptor complex.
abstract: IL-12 and IL-18 are both proinflammatory cytokines that contribute to promoting Th1 development and IFN-gamma expression. However, neither IL-12R nor IL-18R is expressed as a functional complex on most resting T cells. This study investigated the molecular mechanisms underlying the induction of an IL-18R complex in T cells. Resting T cells expressed IL-18Ralpha chains but did not exhibit IL-18 binding sites as detected by incubation with rIL-18 followed by anti-IL-18 Ab, suggesting a lack of IL-18Rbeta expression in resting T cells. Although they also failed to express IL-12R, stimulation with anti-CD3 plus anti-CD28 generated IL-12R. Exposure of these cells to IL-12 led not only to up-regulation of IL-18Ralpha expression but also to induction of IL-18R binding sites on both CD4(+) and CD8(+) T cells concomitant with IL-18Rbeta mRNA expression. The IL-18 binding site represented a functional IL-18R complex capable of exhibiting IL-18 responsiveness. IL-12 induction of an IL-18R complex and IL-18Rbeta mRNA expression was not observed in STAT4-deficient (STAT4(-/-)) T cells and was substantially decreased in IFN-gamma(-/-) T cells. However, the failure of STAT4(-/-) T cells to induce an IL-18R complex was not corrected by IFN-gamma. These results indicate that STAT4 and IFN-gamma play an indispensable role and a role as an amplifying factor, respectively, in IL-12 induction of the functional IL-18R complex.
authors.affiliation: Department of Oncology, Biomedical Research Center, Osaka University Graduate School of Medicine, 2-2 Yamada-oka, Suita, Osaka 565-0871, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Nakahira
authors.forename: M
authors.initials: M
authors.lastname: Tomura
authors.forename: M
authors.initials: M
authors.lastname: Iwasaki
authors.forename: H J
authors.initials: HJ
authors.lastname: Ahn
authors.forename: Y
authors.initials: Y
authors.lastname: Bian
authors.forename: T
authors.initials: T
authors.lastname: Hamaoka
authors.forename: T
authors.initials: T
authors.lastname: Ohta
authors.forename: M
authors.initials: M
authors.lastname: Kurimoto
authors.forename: H
authors.initials: H
authors.lastname: Fujiwara
mesh_terms: D000276:Adjuvants, Immunologic / Q000096:biosynthesis / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D000818:Animals; D001665:Binding Sites / Q000235:genetics / Q000276:immunology; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D007371:Interferon-gamma / Q000096:biosynthesis / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D018664:Interleukin-12 / Q000378:metabolism / Q000502:physiology*; D053727:Interleukin-18 Receptor alpha Subunit; D007399:Interphase / Q000235:genetics / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D018345:Mice, Knockout; D016328:NF-kappa B / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis; D011948:Receptors, Antigen, T-Cell / Q000502:physiology; D018123:Receptors, Interleukin / Q000096:biosynthesis* / Q000378:metabolism; D053724:Receptors, Interleukin-18; D050797:STAT4 Transcription Factor; D015398:Signal Transduction / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology / Q000378:metabolism; D015534:Trans-Activators / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D015854:Up-Regulation / Q000276:immunology
chemical_list: D000276:Adjuvants, Immunologic; D004268:DNA-Binding Proteins; C508573:Il18r1 protein, mouse; D053727:Interleukin-18 Receptor alpha Subunit; D016328:NF-kappa B; D012333:RNA, Messenger; D011948:Receptors, Antigen, T-Cell; D018123:Receptors, Interleukin; D053724:Receptors, Interleukin-18; D050797:STAT4 Transcription Factor; C494091:Stat4 protein, mouse; D015534:Trans-Activators; D018664:Interleukin-12; D007371:Interferon-gamma