title: IL-4 synergistically enhances both IL-2- and IL-12-induced IFN-gamma expression in murine NK cells.
abstract: Interleukin-4 (IL-4) is thought to influence T and natural killer (NK) cells by down-regulating T helper 1 (Th1)-type cytokines like interferon-gamma (IFN-gamma). While investigating IL-4 regulation of IFN-gamma expression, we found that IL-4 synergized with IL-2 or IL-12 to enhance IFN-gamma production and mRNA expression in spleen-derived, IL-2-cultured NK cells, as well as negatively sorted fresh DX5+/CD3- NK cells albeit at lower levels. The positive effect of IL-4 on IL-2-induced IFN-gamma production was dependent upon signal transducer and activator of transcription 6 (Stat6) because this response was virtually abrogated in Stat6-/- mice. Notably, though, IL-12 plus IL-4 synergy on IFN-gamma expression was intact in Stat6-/- mice. In exploring possible molecular mechanisms to account for the synergistic effects of IL-4 on murine NK cells, we found that IL-2 plus IL-4 stimulation resulted in a modest increase in tyrosine phosphorylation of Stat5, while IL-12 plus IL-4 treatment resulted in a more substantial increase in tyrosine-phosphorylated Stat4. Finally, to identify regions of the IFN-gamma promoter that may be involved, NK cells from human IFN-gamma promoter/luciferase transgenic mice were treated with cytokines. NK cells from proximal (-110 to +64) promoter region mice did not respond to cytokine stimulation; however, the intact -565 to +64 IFN-gamma promoter responded synergistically to IL-2 plus IL-4 and to IL-12 plus IL-4 in NK cells. These data demonstrate a role for IL-4 in enhancing IFN-gamma expression in murine NK cells that is partially dependent on Stat6 in IL-2 costimulation and completely independent of Stat6 in IL-12 costimulations.
authors.affiliation: Laboratory of Experimental Immunology, Center for Cancer Research, National Cancer Institute, Building 560, Room 31-23, Frederick, MD 21702-1201, USA. breamj@mail.nih.gov
authors.forename: Jay H
authors.initials: JH
authors.lastname: Bream
authors.forename: Rafael E
authors.initials: RE
authors.lastname: Curiel
authors.forename: Cheng-Rong
authors.initials: CR
authors.lastname: Yu
authors.forename: Charles E
authors.initials: CE
authors.lastname: Egwuagu
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Grusby
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Aune
authors.forename: Howard A
authors.initials: HA
authors.lastname: Young
mesh_terms: D000818:Animals; D004268:DNA-Binding Proteins / Q000378:metabolism; D004357:Drug Synergism; D005786:Gene Expression Regulation / Q000187:drug effects; D007371:Interferon-gamma / Q000096:biosynthesis* / Q000235:genetics; D018664:Interleukin-12 / Q000494:pharmacology; D007376:Interleukin-2 / Q000494:pharmacology; D015847:Interleukin-4 / Q000494:pharmacology; D007378:Interleukins / Q000494:pharmacology*; D007694:Killer Cells, Natural / Q000187:drug effects* / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D008894:Milk Proteins; D010766:Phosphorylation; D011401:Promoter Regions, Genetic / Q000502:physiology; D050797:STAT4 Transcription Factor; D050799:STAT5 Transcription Factor; D050800:STAT6 Transcription Factor; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism / Q000502:physiology
chemical_list: D004268:DNA-Binding Proteins; D007376:Interleukin-2; D007378:Interleukins; D008894:Milk Proteins; D050797:STAT4 Transcription Factor; D050799:STAT5 Transcription Factor; D050800:STAT6 Transcription Factor; C494091:Stat4 protein, mouse; C494100:Stat6 protein, mouse; D015534:Trans-Activators; D018664:Interleukin-12; D015847:Interleukin-4; D007371:Interferon-gamma