Changes In Functional Activation Of Memory T Cells Following Exercise

Abstract

Memory T (TM) cells function to provide long-lasting protection against re-exposure to pathogens. The recall response of TM cells to foreign antigen is quicker and of a greater magnitude than a naïve T cell. How functional activation is altered in TM cells following a bout of exercise is not well known. PURPOSE: To quantify exercise induced changes in surface markers of early, middle, and late stage activation in memory T cells (CD4+CD45RO+CD45RA−) obtained from human subjects. METHODS: Utilizing a cross over design, untrained subjects completed a control and exercise visit. The control visit consisted of 30 min of seated rest while the exercise session entailed 3 sets x 10 reps squat at 70% 1-RM, 3x10 leg press at 70% 1-RM, and 3x10 leg extensions at 70% 1-RM with 2 min rest between sets. Venous blood samples were obtained pre and post each visit. CD4+ T cell isolation from peripheral blood was conducted through negative selection using a Human CD4+ T cell enrichment kit. CD4+ T cells were plated at 1.5 x 106 cells/ml in 200 μl of ImmunoCult T-cell expansion media directly after isolation and costimulated through CD3+CD28 or no stimulation. Cells were incubated for 1 and 3 d at 37°C in a humidified incubator with 5% CO2 and then analyzed by flow cytometry. Early (CD69), middle (CD25), and late (HLA-DR) markers of activation within the CD45RO+CD45RA− subset were quantified at days 0, 1, and 3. Data were analyzed using two-way RMANOVAs. RESULTS: There were no significant differences in any markers of activation at the pre measure (p > .05). Preliminary data suggests exercise does not alter functional activation in non-stimulated CD45RO+CD45RA− cells. There does appear to be a functional impact related to the TM cells ability to respond to stimuli post-exercise with two-fold increases observed in HLA-DR expression for cells co-stimulated through CD3+CD28. CONCLUSIONS: Exercise-induced alterations in functional activation of TM cells will need to be better quantified to determine not only the magnitude of change, but also to identify a kinetic profile of marker expression. Quantification of changes in this subset of cells will aid in our understanding how immune responses following vaccination are affected by exercise stress. Supported by an award through the Dr. George F. Haddix President’s Faculty Research Fund at Creighton University.