title: Research on stress-induced apoptosis of natural killer cells and the alteration of their killing activity in mouse liver.
abstract: OBJECTIVE
  To investigate the stress-induced apoptosis of natural killer (NK) cells and the changes in their killing activity in mouse livers.
  
  
  METHODS
  A restraint stress model was established in mice. Flow cytometry was employed to measure the percentage of NK cells and the changes in their absolute number in mouse liver. The cytotoxicity of hepatic and splenic NK cells was assessed against YAC-1 target cells via a 4 h 51Cr-release assay.
  
  
  RESULTS
  The restraint stress stimulation induced the apoptosis of NK cells in the liver and the spleen, which decreased the cell number. The number and percentage of NK cells in the spleen decreased. However, the number of NK cells in the liver decreased, whereas the percentage of NK cells was significantly increased. The apoptosis of NK cells increased gradually with prolonged stress time, and the macrophage-1 (Mac-1)(+) NK cells were more susceptible to apoptosis than Mac-1(-) NK cells. Large numbers of Mac-1(-) NK cells in the liver, which are more resistant to stress-induced apoptosis, were observed than the Mac-1(-) NK cells in the spleen. The stress stimulation diminished the killing activity of NK cells in the spleen was significantly decreased, but the retention of numerous Mac-1(-) NK cells in the liver maintained the killing ability.
  
  
  CONCLUSIONS
  Significant stress-induced apoptosis was observed among Mac-1(+) NK cells, but not Mac-1(-) NK cells in the mouse liver. Stress stimulation markedly decreased the killing activity of NK cells in the spleen but remained unchanged in the liver.
authors.affiliation: Zhen Ma, Xin Zhou, Hai-Long Yu, Ming-Qi Li, Xue-Feng Bai, Department of Colorectal Surgery, Harbin Medical University Cancer Hospital, Harbin 150040, Heilongjiang Province, China.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Ma
authors.forename: Yang
authors.initials: Y
authors.lastname: Liu
authors.forename: Xin
authors.initials: X
authors.lastname: Zhou
authors.forename: Hai-Long
authors.initials: HL
authors.lastname: Yu
authors.forename: Ming-Qi
authors.initials: MQ
authors.lastname: Li
authors.forename: Chikako
authors.initials: C
authors.lastname: Tomiyama-Miyaji
authors.forename: Toru
authors.initials: T
authors.lastname: Abo
authors.forename: Xue-Feng
authors.initials: XF
authors.lastname: Bai
mesh_terms: D000818:Animals; D017209:Apoptosis; D015415:Biomarkers / Q000032:analysis; D007694:Killer Cells, Natural / Q000276:immunology / Q000473:pathology*; D008099:Liver / Q000276:immunology / Q000473:pathology*; D016177:Macrophage-1 Antigen / Q000032:analysis; D051379:Mice; D008810:Mice, Inbred C57BL; D012149:Restraint, Physical / Q000523:psychology*; D013154:Spleen / Q000276:immunology / Q000473:pathology*; D013315:Stress, Psychological / Q000276:immunology / Q000473:pathology*
chemical_list: D015415:Biomarkers; D016177:Macrophage-1 Antigen
keywords: Cell apoptosis; Killing activity; Natural killer cells; Restraint stress