Expression of lymphocyte subsets after exercise and dexamethasone in high and low stress responders

Purpose: Recent work indicates that among the normal population, persons ca n be classified as low (LR) or high (HR) stress responders based on hypotha lamic-pituitary-adrenal (HPA) axis responses to high-intensity exercise. We studied whether differential activation of the HPA axis affected cytokine production and expression of selected lymphocyte subsets in HR and LR in re sponse to high-intensity exercise after placebo and dexamethasone (DEX; 4 m g). Methods: Healthy HR (N = 12) and LR (N = 10) underwent two exercise tes ts at 90% of VO2max 8 h after placebo or DEX. Expression of lymphocyte surf ace markers (CD3(+), CD4(+), CD8(+), CD56(+)), adhesion molecule markers (i ntercellular adhesion molecule-1/ICAM-1: CD54(+) and L-selectin: CD62L(+)), and concentrations of plasma interleukin 6 (IL-6) were examined before and after exercise. Results: Baseline percentages of CD8(+) and CD56(+) cells were significantly higher, and concentrations of IL-6 and percentages of CD 4(+) cells were significantly lower in HR as compared with LR. The percenta ge of CD54(+) and CD62L(+) cells was not significantly different in HR and LR. DEX significantly reduced the percentage of CD3(+) and CD4(+) and incre ased the percentage of CDS' and CD56(+) subsets; the percent of cells expre ssing CD54(+) increased, whereas CD62L(+) decreased. Exercise-induced chang es in the percentage of lymphocyte subsets were similar to those induced by DEX. Conclusion: In summary, HR and LR have different baseline patterns of IL-6 and lymphocyte subsets, which may reflect differential sensitivity to endogenous glucocorticoids. However, exogenous glucocorticoids induced sim ilar patterns of lymphocyte expression in HR and LR.