Changes in neutrophil surface receptor expression , degranulation , and respiratory burst activity following moderate and high intensity exercise

Intense exercise stimulates the systemic release of a variety of factors that alter neutrophil surface receptor expression and functional activity. These alterations may influence resistance to infection after intense exercise. The aim of this study was to examine the influence of exercise intensity on neutrophil receptor expression, degranulation (measured by plasma and intracellular myeloperoxidase concentrations), and respiratory burst activity. Ten well-trained male runners ran on a treadmill for 60 min at 60% (moderate intensity, MI) and 85% VO 2max (high intensity, HI). Blood was drawn immediately before and after exercise, and 1 h post-exercise. Immediately after HI, the expression of the neutrophil receptor CD16 was significantly below pre-exercise values (P<0.01), while MI significantly reduced CD35 expression below pre-exercise values (P<0.05). One hour after exercise at both intensities, there was a significant decline in CD11b expression (P<0.05), and a further decrease in CD16 expression compared to pre-exercise values (P<0.01). CD16 expression was lower 1 h after HI than 1 h after MI (P<0.01). Immediately after HI, intracellular myeloperoxidase concentration was less than pre-exercise values (P<0.01), while plasma myeloperoxidase concentration was greater (P<0.01), indicating that HI stimulated neutrophil degranulation. Plasma myeloperoxidase concentration was higher immediately after HI than after MI (P<0.01). Neutrophil respiratory burst activity increased after HI (P<0.01). In summary, both moderate and high intensity exercise reduced neutrophil surface receptor expression. Although CD16 expression was reduced to a greater extent after high intensity exercise, this reduction did not impair neutrophil degranulation and respiratory burst activity.