[Effects of leukocytes on vascular tonus]

Numerous epidemiologic studies described an association between the risk of cardiovascular complications and the blood leukocyte count. In addition, an abnormal activation of leukocytes obtained from the coronary venous blood has been found in patients with unstable angina pectoris and acute myocardial infarction. These observations suggest that the elevated leukocyte count and activation is not an epiphenomenon but instead that leukocytes play a role in the pathogenesis of cardiovascular complications. Several in vitro and in vivo experiments were presented demonstrating that activated leukocytes (granulocytes and mononuclear cells) may influence vascular tone by direct and indirect mechanisms. Under certain conditions, activated leukocytes induce a significant vasoconstriction, a phenomenon which is not yet fully understood. This direct contractile effect of activated leukocytes on vascular tone may contribute to the pathogenesis of cardiovascular complications e.g. in patients with coronary artery disease.