Abstract
The purpose of this study was to examine whether cardiovascular fitness, independent of confounding factors, was associated with immune responsiveness to clinically relevant challenges in older adults (60-76 yr). Thirteen sedentary, low-fit (LF; maximal O2 uptake = 21.1 ± 1.1 ml·kg -1·min-1) and 13 physically active, high-fit (HF; maximal O2 uptake = 46.8 ± 3.4 ml·kg -1·min-1) older adults participated in this study. Dietary intake was assessed, and a battery of psychosocial tests was administered. In vivo antibody and ex vivo proliferative and cytokine responses to influenza (Fluzone) and tetanus toxoid (TT) vaccination and delayed-type hypersensitivity skin tests were performed. HF elderly individuals displayed a higher antibody response to two of the three strains included in the Fluzone vaccine as measured by hemagluttination inhibition, but there was no difference between groups in influenza-specific ex vivo proliferation or IFN-γ or IL-10 production. HF elderly individuals exhibited a lower IgG1 response and a tendency for a higher IgG2 response to the TT vaccine. There were, however, no differences in TT-specific ex vivo proliferation or IFN-γ or IL-10 production. In contrast, HF subjects had higher proliferative responses to phytohemagluttinin. In addition, there were no differences in delayed-type hypersensitivity responses to fungal antigens between groups. These results suggest that, after accounting for confounding factors, HF elderly individuals have higher antibody responses to Fluzone vaccine and a Th2 skewing of the antibody response to TT. There was little evidence that HF mounted better cell-mediated immune responses to the Fluzone or TT vaccine measured in peripheral blood cells or to other recall antigens in vivo. Copyright © 2007 the American Physiological Society.