The Effect of Exercise on Natural Killer Cell Activity in Young and Old Subjects

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Abstract
Alterations in immune function have been commonly reported in elderly persons. We have examined the effect of age on the responsiveness of natural killer (NK) cells to in vitro stimulation with recombinant interleukin-2 (rll-2) and in vivo stimulation with exercise in 17 healthy subjects (8 young and 9 old). The old subjects were found to have NK cell numbers and function that were not significantly different from the young subjects at baseline. They also responded as well as the young subjects to rlL-2 stimulation of NK cells in vitro. In response to maximal bicycle ergometry exercise, there was a marked rise in NK activity in the old (7.52 ± 1.71LU/106 pre-exercise vs 15.20 ± 3.27 Lu/106 post-exercise, p < .03) and the young (6.29 ± .48 LU 106 vs 14.56 ± 1.86 lu 106, p < .005) subjects. Lymphocytes bearing the NK marker leu LLa also rose significantly post-exercise in both old and young subjects. We conclude that healthy elderly subjects increase their NK activity in response to the acute stressor, exercise, at least as effectively as do young subjects.