Leukocyte Adhesion Molecule Expression in Health and Cardiovascular Disease: What is the Significance of Changes Induced by Acute Bouts of Exercise? pp. 187-221
Authors: John M. Saxton
Abstract: Moderate or intense aerobic exercise causes a transient redistribution of circulating leukocytes. This is characterized by lymphocytosis and granulocytosis during exercise and a more pronounced granulocytosis, accompanied by lymphocytopenia during recovery. The exercise-induced redistribution of circulating leukocytes is mediated by hemodynamic factors and increases in the circulating levels of catecholamines during exercise and cortisol during late exercise and recovery. Quantitative changes in the numbers of circulating leukocytes during exercise are accompanied by changes in functional capacity of neutrophils and monocytes at the cellular level and an improvement in natural killer (NK) cell function that is largely attributable to the increased proportion of circulating NK cells. Changes in the expression of immune cell surface proteins such as adhesion molecules could be implicated in the immunomodulatory effects of acute exercise and may be a factor in the reduced susceptibility to infections in humans undertaking regular moderate exercise. However, exercise-induce changes in immune cell microbicidal function and adhesion molecule expression can be interpreted in a number of different ways and future studies should investigate how changes in immune function relate to the incidence of subsequent infections and other robust indicators of health status. The inflammatory milieu underpinning the development of atherosclerotic lesions is reflected by elevated concentrations of circulating adhesion molecules and activated peripheral blood leukocytes. Moderate and intense aerobic exercise can activate cells of the immune system in patients with atherosclerotic conditions, such as peripheral arterial disease and coronary heart disease. This may be indicative of a systemic inflammatory response, which could potentially contribute to the atherosclerotic disease process. However, participation in regular aerobic exercise training can have positive effects on resting and post exercise inflammatory markers, including soluble and leukocyte adhesion molecules, in patients with atherosclerotic conditions. Future studies that examine changes in resting inflammatory markers evoked by exercise training in relation to the progression/regression of atherosclerosis and cardiovascular mortality will provide more insight into the beneficial effects of exercise on arterial function in patients with cardiovascular disease.