Aerobic training increases the stimulated percentage of CD4+CD25+ in older men but not older women

The purpose of the present study was to determine whether 12 months of moderate intensity cycling would increase the expression of IL-2 (CD25+) receptors in T helper (CD4+) lymphocytes in men and women aged 65-75 years. Fourteen men and 10 women completed 52 weeks of moderate intensity cycling (60% VO2peak). Subjects trained (TR) three times per week for 45 min per session. Eight age-matched untrained (UT) male and eight UT female subjects acted as controls. Resting blood samples were taken from TR and UT subjects every 4 weeks. Leukocyte concentration was measured using a full blood count. PHA-stimulated CD4+ lymphocytes were analysed for changes in the expression of CD25+, by flow cytometry. Training significantly increased VO2peak (l min...1, ml kg...1 min...1) in male (+14.3, +16%) and female (+16.7, +27.8%) groups. The TR male group showed a significantly lower percentage of CD4+CD25+ than the male UT in January but the TR male percentage was significantly higher than the UT male group during February, March, April, May, June, September B and December. The female TR group showed a significantly higher percentage CD4+CD25+ than the female UT only during July. There were also significant sequential monthly changes in the percentage ofCD4...CD25... for male and female UT and TR groups. Significant increases in the percentage of CD4+CD25+ in the male TR group suggest training-enhanced lymphocyte mitogenic responsiveness. Moderate intensity long-term training may increase the recruitment of active memory CD4+CD25+ in men rather than women.