Frequent participation in high volume exercise throughout life is associated with a more differentiated adaptive immune response

Exercise induces changes in the immune system depending on its intensity and duration. For example, transient states of immunodepression can be induced after acute intense physical activity whereas beneficial anti-inflammatory effects of moderate chronic exercise on many diseases and longevity have been described. To study the impact of high volume exercise over a lifetime on aspects of immunity we compared immunological features of 27 young and 12 elderly athletes with 30 young and 26 elderly non-athletes stratified by their CMV serostatus. We characterized blood leukocyte and lymphocyte subpopulations by flow cytometry, quantified TREC content, and measured activation and proliferation ability of T-lymphocytes in the presence of anti-CD3. NK-cells functionality was determined in response to K-562, 721.221 and 721.221-AEH cell-lines. High volume physical activity reduced the total number of circulating leukocytes, neutrophils, and lymphocytes. In the lymphocyte compartment, athletes had higher frequencies of NK-cells and CD8+ T-lymphocytes, whereas CD4+ T-lymphocytes were present at significantly lower levels in CMV-seropositive athletes. We found, in the high volume physical activity individuals, a higher degree of differentiation in CD4+ T-lymphocytes. CD8+ T-lymphocytes from young athletes had reduced TREC content and lower frequencies of recent thymic emigrants. Furthermore, the functional ability of CD4+ and CD8+ T-lymphocytes was significantly impaired in young but not in elderly athletes, and may be compensated for significantly higher activation and degranulation of NK-cells. In conclusion, high volume exercise throughout life appears to be associated with increased levels of biomarkers that are associated with an aging immune system, which are partially reduced with physiological aging.