Immune response to a single bout of exercise in young and elderly subjects

The purpose of this investigation was to examine alterations in lymphocyte proliferation activity and T cell subsets following an acute bout of exercise in young and old subjects. Six young (26 +/- 3 years) and nine old (69 +/- 5 years) male subjects were tested at rest and immediately after 20 min of submaximal exercise at 50% peak work capacity. Arterial blood was sampled from an indwelling catheter for catecholamine and immunology assays. Peripheral blood lymphocytes were isolated for mitogen-induced phytohemagglutinin (PHA) proliferation capacity. Lymphocyte subsets were analyzed by dual-labeled flow cytometry. As has been shown in previous studies, baseline proliferative responsiveness was significantly lower in the old (down arrow 22%) compared to the young subjects. In response to submaximal exercise, proliferative responsiveness to PHA increased significantly in the young subjects (up arrow 55%), however, for the old subjects this response did not differ significantly from resting values (up arrow 18%). The number of total lymphocytes, as well as CD4(+) and CD8(+) T cell subsets, at rest were lower for old subjects compared with young. Exercise-induced increases in T cell subset populations were similar across age groups. It was concluded that, while having lower initial T cell numbers and PHA responsiveness, immunoresponsiveness during a single bout of exercise is, in general, maintained in old when compared to young individuals. (C) 1998 Elsevier Science Ireland Ltd.