Semester of Graduation

Spring 2019


Master of Science (MS)



Document Type



Evidence suggests high-intensity exercise training increases incidence of upper respiratory infection in young-adult athletes (Spence et al. 2007). Collegiate athletes experience chronic stress, which has been shown to result in increased proportions of late-differentiated CD8+ T-cells of a dysfunctional phenotype (Bosch et al. 2009). However, many studies fail to consider possible moderators such as psychological stress and cytomegalovirus (CMV) infection. Purpose: To examine the impact of psychological stress, CMV infection, and exercise on proportions of early- and late-differentiated CD4+ and CD8+ T-cells in collegiate swimmers over a 7-month training period. Methods: Data were collected from NCAA Division 1 swimmers (13 M, 12 F: 19.7 ± 0.8 yrs) at 3 timepoints: early-season (October, n=18), immediate post-season (April, n=23), and off-season (June, n=10). Participants performed an in-water anaerobic capacity power test, consisting several 25-yard swims with increasing resistance. Early-morning serum samples were taken before (resting) and immediately following exercise. Flow cytometry after monoclonal antibody staining determined proportions of CD4+ and CD8+ T-cells categorized as early- (CD57-/KLRG1-) or late- (CD57+/KLRG1+) differentiated. ELISA determined resting serum cortisol concentration and CMV serostatus (CMV+ or CMV-). Data presented as mean ± SE. Results: Proportions of resting early- and late-differentiated CD4+ (p=0.025 and p=0.001, respectively) and late-differentiated CD8+ (p=0.006) T-cells differed between April and October timepoints. In April, exercise induced a preferential mobilization (% change) of late- (111.77 ± 32.5 %) compared to early- (-5.72 ± 1.6 %) differentiated CD4+ T-cells and late- (54.75 ± 7.9 %) compared to early- (-25.35 ± 3.2 %) differentiated CD8+ T-cells. Similar mobilization patterns occurred at October and June timepoints. Serum cortisol concentration had no effect on immune cell proportions. CMV+ had lower resting proportions of early-differentiated CD4+ (p=0.007) and CD8+ (p=0.045) T-cells compared to CMV-. Conclusions: Training status partially regulates T-cell proportions over time. CMV infection results in unfavorable changes in the CD4+ T-cell repertoire, which may compromise immune protection against novel pathogens.



Committee Chair

Spielmann, Guillaume