Aerobic fitness is associated with lower proportions of senescent blood T-cells in man

Senescent T-cells accumulate with age, lowering the naive T-cell repertoire and increasing host infection risk. As this response is likely to be influenced by certain lifestyle factors, we examined the association between aerobic fitness (VO2max) and the age-related accumulation of senescent T-cells. Blood lymphocytes from 102 healthy males (18-61 yr) were analyzed for KLRG1, CD57, CD28, CD45RA, CD45RO surface expression on CD4+ and CD8+ T-cells by 4-color flow cytometry. Advancing age (yr) was positively associated with the proportion (%) of senescent (KLRG1+/CD57+; KLRG1+/CD28-) CD4+ (B = 1.00; 1.02) and CD8+ (B = 0.429; 1.02) T-cells and inversely associated with naive (KLRG1-/CD28+) CD4+ (B = 1.000) and CD8+ (B = -0.993) T-cells. VO2max was inversely associated with senescent CD4+ (B = -0.97) and CD8+ (B = -0.240). Strikingly, age was no longer associated with the proportions of senescent or naive T-cells after adjusting for VO2max, while the association between VO2max and these T-cell subsets. with-stood adjustment for age, BMI and percentage body fat. Ranking participants by age-adjusted VO2max revealed that the highest tertile had 17% more naive CD8+ T-cells and 57% and 37% less senescent CD4+ and CD8+ T-cells, respectively, compared to the lowest tertile. VO2max was not associated with latent cytomegalovirus (CMV), Epstein-Barr virus (EBV) or herpes simplex virus-1 (HSV-1) infection, indicating that the moderating associations of VO2max were not confounded by persistent viral infections. This is the first study to show that aerobic fitness is associated with a lower age-related accumulation of senescent T-cells, highlighting the beneficial effects of maintaining a physically active lifestyle on the aging immune system. (C) 2011 Elsevier Inc. All rights reserved.