Physical Activity and Immune Senescene in Men

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A cross-sectional survey examined whether habitual endurance exercisers retained a higher level of T cell function than sedentary individuals in old age. Subjects, all male, comprised 17 elderly runners, 16 young controls and 19 elderly controls (mean ages <plus-minus> SD : 63.8 <plus-minus> 3.3,23.6 <plus-minus> 1.6, and 65.8 <plus-minus> 3.5, yr, respectively) . Samples of peripheral blood were collected at least 36 h after exercise. Group comparisons were made on data from non-smokeres only, using one-way ANOVA and a Bonferroni adjustment for post-hoc multiple comparisons. Lymphocyte functions were assessed as adjusted activity per major responding cell as well as the usual unadjusted activity. In comparison wtih the young subjects, both elderly groups had lower circulating CD3^+ and CD8^+ counts (group effects : P=.029, P=.001, respectively) , with a trend to a higher CD4/CD8 ratio, but higher percentages of activated CD3^+, and "memory" CD4^+ and CD8^+ cells (all, P<.001) . Prolif … More erative responses to phytohemagglutinin (PHA) , pokeweed mitogen (PWM) and alloantigens (mixed lymphocyte reaction) were markedly reduced in the elderly (for unadjusted activities, P<.001, P<.001 and P=.024, respectively). IL-2 production tended to be decreased in the elderly sedentary subjects (P=.058 vs young subjects) . However, natural killer cell activity was not impaired, and IL-1beta, IFN-gamma and IL-4 production remained unchanged in the elderly sedentary subjects. Comparison between the active and sedentary elderly groups showed no differences in circulating counts of immunocompetent cells. However, the active elderly subjects demonstrated significantly greater proliferative responses to PHA (P=.016 for unadjusted and P=.034 for adjusted activity) , and to PWM(P=.011 and P=.040, respectively) , and higher rates of IL-2 (P=.021), IFN-gamma (P=.015) and IL-4 production (P=.012) . These results suggest that endurance training in later life is associated with a lesser age-related decline in certain aspects of circulating T cell function and related cytokine production. Less