Endurance-training effects on intracellular calcium and iron in CD4+ lymphocytes in young and old men
Broadbeant, S 2013, 'Endurance-training effects on intracellular calcium and iron in CD4+ lymphocytes in young and old men', paper presented to the 60th ACSM Annual Meeting and 4th World Congress on Exercise is Medicine, Indianapolis, Indiana, 28 May - 1 June.
Regular exercise is thought to maintain or improve the adaptive immune (lymphocyte) response but there is little data on the long-term exercise effects on CD4+ activation in young and older individuals.
PURPOSE: To investigate if 12 months of aerobic/endurance training would enhance CD4+ activation via increased CD25 receptor expression and density in trained older and young men compared to sedentary controls.
METHODS: We compared young (30±5 yr) trained (TRY, n = 14) and sedentary (UTY, n = 12) men to older (69±5 yr) trained (TRO, n = 14) and sedentary (UTO, n = 10) men for 12 months. Older men cycled for three 50 min sessions per week (60-70% VO2peak) while the TRY group completed daily endurance training (90-120 min per day, 60-80% VO2peak). Venous blood was analysed every month for resting lymphocyte count and CD4+CD25+ expression and density by flow cytometry. Results were analysed by repeated measures two-way ANOVA (time vs group) with Bonferroni post hoc test (between-group and between-month), with p<0.05.
RESULTS: The TRY group had a significantly higher concentration of CD4+ than the UTY for 4 months (37±7%); there was no difference in lymphocyte count between TRO and UTO. The TRO group had a significantly greater percentage of CD4+CD25+ than the UTO group (39±16%) for 8 months, and TRY (52±20%) and UTY (57±19%) groups for 6 months. The TRO, TRY and UTY groups showed a significantly different % of CD4+CD25+ compared to the previous month in April, May, October and November. CD25 density was significantly greater in the TRY compared to UTY group (34±11%) for 10 months, and in TRY compared to TRO (39±13%) and UTO (44±12%) groups for 10 months. CD25 density was significantly different to the previous month for TRY and UTY in April, May, July, August, September, October; for TRO and UTO, in February, September.
CONCLUSION: Moderate intensity/duration endurance training increased the percentage of CD4+ expressing CD25+ in older men, possibly by increasing memory cells. Endurance training in young athletes increased CD4+CD25+ density rather than the number/percentage of lymphocytes positive for the receptor. Exercise may increase the CD4+ response through different mechanisms depending upon age. Furthermore, there are seasonal differences in CD4+CD25+ expression which may affect adaptive immunity.