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

1 School of Human Movement Studies, The University of Queensland, St. Lucia, Brisbane, Queensland 4072, Australia; 2 Department of Health Sciences and Social Welfare, School of Human Sciences, Waseda University, Tokorozawa 359-1192; 3 Oyokyo Kidney Research Institute, Aomori 036-8243; and 4 Department of Environmental Science, Exercise and Sports Science, Yokohama City University, Yokohama 236-0014, Japan Submitted 11 December 2003 ; accepted in final form 5 April 2004 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 exercise (MI)] and 85% maximal oxygen consumption [high-intensity exercise (HI)]. Blood was drawn immediately before and after exercise and at 1 h postexercise. Immediately after HI, the expression of the neutrophil receptor CD16 was significantly below preexercise values ( P < 0.01), whereas MI significantly reduced CD35 expression below preexercise 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 with preexercise 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 preexercise values ( P < 0.01), whereas 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 MI and HI reduced neutrophil surface receptor expression. Although CD16 expression was reduced to a greater extent after HI, this reduction did not impair neutrophil degranulation and respiratory burst activity. myeloperoxidase; CD16; receptor shedding; cytokines Address for reprint requests and other correspondence: J. S. Coombes, School of Human Movement Studies, The Univ. of Queensland, St. Lucia, Brisbane, QLD 4072, A