Higher antibody, but not cell-mediated, responses to vaccination in high physically fit elderly

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.