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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., Conclusion: 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.

As we age, the composition of our peripheral leukocytes changes dramatically. Many of these alterations contribute to the general immune dysfunction that burdens the elderly, which in turn, contributes to increased susceptibility to disease. MDSCs represent a heterogeneous population of immunosuppressive leukocytes that are elevated in the peripheral blood of cancer patients. Given the relation between cancer incidence and age, this study examined the frequency of peripheral blood CD33(+)HLA-DR(-) MDSCs across three cohorts: healthy adults (19-59 years old), community-dwelling seniors (61-76 years old), and frail elderly (67-99 years old). This analysis is the first to demonstrate that MDSCs and specifically the CD11b(+)CD15(+) MDSC subset are increased with age. Proinflammatory cytokines that are required for the differentiation of MDSCs (e.g., TNF-α, IL-6, and IL-1β) were similarly found to be increased in the serum of the frail elderly. Furthermore, the proportion of MDSCs and the CD11b(+)CD15(+) subset were found to be elevated significantly in elderly donors with a history of cancer. This age-related elevation in the frequency of MDSCs may contribute to the increased cancer incidence that occurs with age. Further investigation into the functional consequences of elevated MDSCs will provide valuable insight into the progression of age-related pathologies.

Objectives To determine whether immune phenotypes associated with immunosenescence are predictive of frailty and mortality within 1-year in elderly nursing home residents. Design Cross sectional study of frailty; prospective cohort study of mortality. Setting Thirty-two nursing homes in four Canadian cities between September 2009 and October 2011. Participants Nursing home residents aged 65 and older (N = 1,072, median age 86, 72% female). Measurements After enrollment, peripheral blood mononuclear cells were obtained and analyzed using flow cytometry for CD4+ and CD8+ T-cell subsets (naïve, memory (central, effector, terminally differentiated, senescent), and regulatory T-cells) and cytomegalovirus ( CMV)-reactive CD4+ and CD8+ T-cells. Multilevel linear regression analysis was performed to determine the relationship between immune phenotypes and frailty; frailty was measured at the time of enrollment using the Frailty Index. A Cox proportional hazards model was used to determine the relationship between immune phenotypes and time to death (within 1 year). Results Mean Frailty Index was 0.44 ± 0.13. Multilevel regression analysis showed that higher percentages of naïve CD4+ T-cells ( P = .001) and effector memory CD8+ T-cells ( P = .02) were associated with a lower mean Frailty Index, whereas a higher percentage of CD8+ central memory T-cells was associated with a higher mean Frailty Index score ( P = .02). One hundred fifty one (14%) members of the cohort died within 1 year. Multivariable analysis showed a significant negative multiplicative interaction between age and percentage of CMV-reactive CD4+ T-cells (hazard ratio = 0.87, 95% confidence interval = 0.79-0.96). No other significant factors were identified. Conclusion Immune phenotypes found to be predictive of frailty and mortality in this study can help further understanding of immunosenescence and may provide a rationale for future intervention studies designed to modulate immunity. [ABSTRACT FROM AUTHOR]

Tumor necrosis factor (TNF), a potent inflammatory cytokine, and mitochondrial DNA (mtDNA), a product of inflammation-induced tissue damage, increase with age (“inflammaging”) and many chronic diseases. Peripheral blood neutrophils, a critical component of innate immunity, have also been shown to be altered with age, and are exceptionally sensitive to external stimuli. Herein, we describe that the phenotype of neutrophils from the advanced-age, frail elderly (ELD) is determined by levels of circulating TNF and mtDNA. Neutrophils from ELD donors are morphologically immature, and have higher levels of intracellular reactive oxygen species (ROS) and expression of the activation markers CD11b and HLA-DR. The frequency of CD11b ++ neutrophils correlated with plasma TNF, and recombinant TNF elevated neutrophil CD11b ex vivo and in vivo . Furthermore, neutrophils from aged TNF-deficient mice expressed CD11b similar to young counterparts. The frequency of HLA-DR + neutrophils, on the other hand, positively correlated with circulating mtDNA, which increased neutrophil HLA-DR expression in a dose-dependent manner ex vivo . Cell-surface TLR-9 expression, however, was unaltered on neutrophils from ELD donors. In summary, we provide novel evidence that products of age-related inflammation modulate neutrophil phenotype in vivo . Given this, anti-inflammatory therapies may prove beneficial in improving neutrophil functionality in the elderly. [ABSTRACT FROM AUTHOR]