STUDIES ON THE EFFECTS OF NUTRITION AND EXERCISE ON THE DECREASED CELLULAR IMMUNITY IN THE AGED

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It is estimated that one fourth of Japanese population in the 21st century will be older than 65 years of age. Accompanying this increased percentage of elderly people will be an increased incidence of life-related diseases and infectious diseases associated with the reduced cellular immunity that occurs during aging. If this decrease of cellular immunity can be minimized, it might improve the health of older persons and prolong life expectancy. This study was conducted to investigate the effect of nutrition and exercise on decreased cellular immunity in the aged. Obesity (BMI>30) in the aged induced marked decreases of T cell proliferation following in vitro activation with PHA or Con A and natural killer cell (NK) activity. In contrast, exercise training improved not only the decreased phagocytic activity but also the responsiveness to macrophage-activating factor (MAF) produced from activated T cells among alveolar macrophages (AM) in aged rats (24 months old). In addition, reductio … More n in the activities of daily life (ADL) was closely associated with decreased NK activity in elderly people admitted to health service facilities for the aged. This study suggests that obesity is one of the risk factors for deteriorating health in the aged, and that maintenance of physical activity in the aged is important for retaining cellular immunity in this population group.Another study was conducted to investigate the relationship between cellular immunity and nutritional state in the aged. Subjects were 68 men (aged 66 to 89) and 127 women (aged 65 to 88) living in Yamaguchi prefecture. Nutritional state was evaluated by prognostic nutritional index (PNI), which was calculated by using biochemical parameters such as serum albumin and transferrinm triceps skin-fold thickness and total lymphocyte count. Proliferation of peripheral blood lymphocytes with PHA or Con A was decreased with aging, which was closely associated with the decreased percentage of CD3ィイD1+ィエD1 T cells. Although the percentage of CD56+ T cells in peripheral blood was significantly increased with aging, NK activity was inversely decreased. As it is known that vitamin E has an ability to modulate cellular immune functions, we measured vitamin E level in their bloods. In addition, macrophages have an important role in the maintenance of cellular immunity in the aged. Especially, nitric oxide (NO) produced from macrophages is known to have an inhibitory effect on lymphocyte proliferation following in vitro simulation with mitogens. In this study we tried to investigate relationship between NO production and the decreased cellular immunity in the aged. As its result, we have found that there is a positive correlation between α-tocopherol/VLDL choloesterol and proliferation of peripheral blood lymphocytes with Con A and there is a negative correlation between NO concentration and proliferation of peripheral blood lymphocytes with Con A. in addition, we have also found that there is a negative correlation between NO concentration and α-tocopherol/VLDL cholesterol. These results suggest that the decreased cellular immunity in the aged is associated with increased NO production and that it is important for the maintenance of cellular immunity in the aged to keep a high vitamin E state. Less