The increase in life expectancy of the populations has fostered the interest in the understanding of the ageing process. This process, called immunosenescence, is associated with an immunedysregulation, notably of the Th-1/Th-2 balance, with progressive predominance of Th-2 responses. Decreased IFN-g secretion and increased IL-4 and IL-10 secretion are seen in lymphocytes from aged as compared with young adults. The production of IL-1, IL-6, IL-8 e TNF- is also increased, contrasting with the decreased production of IFN-g and IL-2. The reduced efficacy of vaccination and the increased rate of infections in this population are likely due to the decreased number of naïve T cells. In the elderly, the accumulation of T CD8+CD28- cells (the loss of CD28 expression being a marker of replicative senescence) is also associated with the lack of control of infections. The detrimental impact of ageing and immunosenescence led to the development of protocols aiming at reducing this impact. One of such protocols is the regular practice of exercises. This study aims to verify whether aged people undergoing regular moderate physical activity (participation in training for competition of up to 10.000 meters) have improvement in immunological parameters and, genotypically, with slowing of the shortening of telomere length. For this, 40 healthy aged athletes (>65 years) will be studied in comparison with 40 healthy aged (>65 years) sedentary individuals. Telomere length of several subpopulations (TCD8+CD28+ and TCD8+CD28- cells, naïve and memory TCD4+ cells) will be studied by the Flow-FISH method. In parallel, the proliferative and cytokine responses (IL-2, IL-10, TNF-± e INF-g) and markers of apoptosis of these cells will be evaluated.
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