title: [Effects of simulated weightlessness on biological activity of human NK cells induced by IL-2].
abstract: OBJECTIVE
  To investigate the effects of simulated weightlessness on the activity of human natural killer (NK) cells induced by interleukin 2 (IL-2).
  
  
  METHODS
  Primary human NK cells were cultured under simulated weightlessness condition. The viability of NK cells was determined by CCK-8 assay; cell apoptosis was analyzed by flow cytometry combined with annexin V-FITC/PI staining; the level of interferon γ (IFN-γ) was examined by ELISA; the mRNA levels of IL-12 receptor genes were detected by reverse transcription PCR.
  
  
  RESULTS
  Compared with control cells cultured in normal gravity, IL-2-induced cell proliferation rate of NK cells cultured in simulated weightlessness decreased by 13.6% and 31% at 24 and 48 hours, respectively; the cell apoptotic rate increased by 8% and 19%; IL-2-induced IFN-γ production was inhibited by 25.2% and 47.8%; the cytotoxicity of NK cells induced by IL-2 was reduced by 7% and 18%; IL-12-induced IFN-γ production was suppressed by 21.8% and 58.8% in IL-2 pretreated cells at 24 and 48 hours, respectively. In addition, the mRNA levels of IL-12 β1 and β2 receptor genes were significantly down-regulated in the cells cultured in simulated weightlessness.
  
  
  CONCLUSIONS
  Simulated weightlessness can inhibit the proliferation of NK cells induced by IL-2, promote NK cell apoptosis, impair IL-2-induced IFN-γ production and cytotoxicity in NK cells, and inhibit IL-12-induced IFN-γ production through down-regulating IL-12 receptor gene expression in NK cells.
authors.affiliation: Hospital of North West Agriculture and Forestry University, Yangling 712100; Department of Medical Psychology, Fourth Military Medical University, Xi'an 710032, China.
authors.forename: Wenli
authors.initials: W
authors.lastname: Liu
authors.affiliation: Department of Medical Psychology, Fourth Military Medical University, Xi'an 710032, China.
authors.forename: Xia
authors.initials: X
authors.lastname: Zhu
authors.affiliation: Hospital of North West Agriculture and Forestry University, Yangling 712100, China.
authors.forename: Li
authors.initials: L
authors.lastname: Zhao
authors.affiliation: Hospital of North West Agriculture and Forestry University, Yangling 712100, China.
authors.forename: Xiling
authors.initials: X
authors.lastname: Yang
authors.affiliation: Department of Medical Psychology, Fourth Military Medical University, Xi'an 710032, China.
authors.forename: Fei
authors.initials: F
authors.lastname: Cao
authors.affiliation: College of Veterinary Medicine, North West Agriculture and Forestry University, Yangling 712100, China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Huang
authors.affiliation: Hospital of North West Agriculture and Forestry University, Yangling 712100, China.
authors.forename: Peihong
authors.initials: P
authors.lastname: Mu
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D007371:Interferon-gamma / Q000096:biosynthesis; D018664:Interleukin-12 / Q000494:pharmacology; D007376:Interleukin-2 / Q000494:pharmacology*; D007694:Killer Cells, Natural / Q000187:drug effects* / Q000276:immunology; D008297:Male; D008875:Middle Aged; D012333:RNA, Messenger / Q000032:analysis; D053707:Receptors, Interleukin-12 / Q000235:genetics; D014893:Weightlessness
chemical_list: D007376:Interleukin-2; D012333:RNA, Messenger; D053707:Receptors, Interleukin-12; D018664:Interleukin-12; D007371:Interferon-gamma