Nutrition and Dietetics Department, Monash University, Melbourne, Australia.
Endocrine Centre of Excellence, Department of Medicine, Austin Health, University of Melbourne, Melbourne, Australia.
Immun Ageing. 2013 Aug 5;10:32. doi: 10.1186/1742-4933-10-32. eCollection 2013.
This study examines associations between markers of nutritional status and lymphocyte subsets and seeks to determine if lymphocyte profile is predictive of survival in elderly Australians residing in aged care facilities. Aged yet still ambulatory subjects (n = 88, 73% female) living in low-level care and requiring minimal assistance were studied for 143 weeks. At baseline when participants were aged (mean ± SD) 86.0 ± 5.9 years, dietary intake was determined by 3-day weighed food record, body composition was assessed by dual energy X-ray absorptiometry (DXA) and a venous blood sample was taken.
At baseline assessment, study participants were consuming nutrient-poor diets and most had symptoms of chronic disease. Although overweight, 40% exhibited sarcopenia. Markers of nutritional status did not relate closely to immune cell numbers (absolute or relative), which on average were within the normal range. Men had lower numbers of CD3(+)CD4(+) cells (CD4(+) T cells), a higher proportion of CD3(-) CD16(±) CD56(±) (natural killer (NK) cells) and a higher ratio of NK: CD4(+) T cells than women (all P < 0.05). The main age-related changes evident were decreased T cells, particularly low CD4(+) T cell counts, and increased numbers of CD19(+) (B-cell) and NK cells. During the 143 week duration of follow-up, about one quarter of the study participants died, with death more likely in men than women (P < 0.01). Poor survival was predicted by the presence of decreased numbers of CD4(+) T cells (hazard ratio (HR) 0.919, P < 0.01) and expanded numbers of NK cells (HR 1.085, P < 0.05) in the blood, and therefore the presence of a high NK: CD4(+) T cell ratio (HR 30.521, P < 0.01).
THE NK: CD4(+) T cell ratio may potentially have clinical utility for predicting longevity in elderly populations. Further studies are needed in other elderly populations to confirm this finding.
本研究旨在探讨营养状况标志物与淋巴细胞亚群之间的关系，并确定淋巴细胞谱是否可以预测居住在老年护理机构的澳大利亚老年人的生存情况。研究对象为 88 名仍能行动但年龄较大的（73%为女性）、生活在低水平护理且仅需最低限度帮助的老年人，研究时间为 143 周。在参与者年龄为（平均值±标准差）86.0±5.9 岁时进行基线评估，通过 3 天的称重食物记录确定饮食摄入量，通过双能 X 射线吸收法（DXA）评估身体成分，并采集静脉血样。
在基线评估时，研究参与者的饮食中营养素含量较低，且大多数人患有慢性疾病症状。尽管超重，但 40%的人存在肌肉减少症。营养状况标志物与免疫细胞数量（绝对值或相对值）没有密切关系，平均而言，免疫细胞数量处于正常范围内。男性的 CD3(+)CD4(+)细胞（CD4(+)T 细胞）数量较低，CD3(-) CD16(±) CD56(±)（自然杀伤（NK）细胞）比例较高，NK: CD4(+)T 细胞比值高于女性（均 P<0.05）。最明显的与年龄相关的变化是 T 细胞减少，尤其是 CD4(+)T 细胞计数降低，以及 CD19(+)（B 细胞）和 NK 细胞数量增加。在 143 周的随访期间，约四分之一的研究参与者死亡，男性的死亡率高于女性（P<0.01）。CD4(+)T 细胞数量减少（风险比（HR）0.919，P<0.01）和 NK 细胞数量增加（HR 1.085，P<0.05）预示着预后不良，因此 NK: CD4(+)T 细胞比值升高（HR 30.521，P<0.01）。
NK: CD4(+)T 细胞比值可能对预测老年人群的寿命具有潜在的临床应用价值。需要在其他老年人群中进行进一步研究以证实这一发现。
