title: Immunosenescence in the nursing home elderly.
abstract: BACKGROUND
  To describe T-cell and natural killer (NK) cell phenotypes within nursing home elderly.
  
  
  METHODS
  Nursing home elderly were recruited from four nursing homes in Hamilton, Ontario between September 2010 and December 2011. Healthy adults were recruited from McMaster University between September 2011 and December 2011. Nursing home elderly ≥65 years were eligible; those on immunosuppressive medications were excluded. Healthy adults ≥18-64 years were eligible. CD8+ and CD4+ T-cells% and their subsets, T-regs% and NK cell subset% were compared between the nursing home elderly and healthy adults.
  
  
  RESULTS
  262 nursing home elderly were enrolled; median age 87 years and 81% were female. 16 healthy adults were enrolled; median age 31 and 50% were female. There was no significant difference between CD8+ T-cell% in nursing home and healthy adults (median 17.1 versus 18.0, p = 0.56), however there were fewer naïve CD8 + T-cell% (median 0.9 versus 5.2, p < 0.001), more terminally differentiated CD8 + T-cell% (median 7.3 versus 4.1, p = 0.004) and more senescent T-cell% (median 5.3 versus 3.1, p = 0.04) in the nursing home elderly. There were more CD4+ T-cell% in the nursing home elderly compared to healthy adults (median 45.5 versus 37.1, p = 0.001). Nursing home elderly had a higher CD4+/CD8+ ratio than healthy adults (2.6 versus 1.9, p = 0.048), higher T-reg% (median 1.8 versus 0.8, p < 0.001) and increased mature NK cell% (median 12.1 versus 5.4, p = 0.001) compared to healthy adults.
  
  
  CONCLUSIONS
  Differences in naïve CD8+ T-cells, terminally differentiated and senescent CD8+ T-cells, T-regs and NK cell subsets were similar to studies involving community dwelling elderly. In contrast, the CD4+/CD8+ ratio was higher in nursing home elderly.
authors.affiliation: Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, ON L8S 4 K1, Canada. johnsj48@mcmaster.ca.
authors.forename: Jennie
authors.initials: J
authors.lastname: Johnstone
authors.forename: Jamie
authors.initials: J
authors.lastname: Millar
authors.forename: Alina
authors.initials: A
authors.lastname: Lelic
authors.forename: Chris P
authors.initials: CP
authors.lastname: Verschoor
authors.forename: Stephen D
authors.initials: SD
authors.lastname: Walter
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Devereaux
authors.forename: Jonathan
authors.initials: J
authors.lastname: Bramson
authors.forename: Mark
authors.initials: M
authors.lastname: Loeb
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000276:immunology*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology* / Q000378:metabolism / Q000473:pathology; D003430:Cross-Sectional Studies; D005260:Female; D016330:Frail Elderly; D006707:Homes for the Aged / Q000639:trends*; D006801:Humans; D007694:Killer Cells, Natural / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D008297:Male; D009735:Nursing Homes / Q000639:trends*; D009864:Ontario / Q000453:epidemiology
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