Leukocytes and the Risk of Ischemic Diseases

Abstract

Predictive indexes for atherosclerotic risk are imperfect, suggesting that there are predictive factors not commonly considered. Such a factor may be the white blood cell (WBC) count. Epidemiologic studies have shown correlations between the WBC count and the risk of myocardial infarction and stroke. The risk of acute myocardial infarction is approximately four times as great in persons with WBC counts high in the normal range (greater than 9000/microL [9 X 10(9)/L]) as in persons with WBC counts low in the normal range (less than 6000/microL [6 X 10(9)/L]); only 50% to 65% of the excess risk of the high-count individuals is explainable by tobacco smoking (which covaries with WBC count). A high WBC count also predicts greater risk of reinfarction and of in-hospital death. Less rigorously studied, the constitutional neutropenia of Yemenite Jews appears to afford protection against atherosclerotic disease. Among WBC types, the strongest epidemiologic association has been with the neutrophil count. Such a predictive value of WBC count is plausible and satisfying, because WBCs make a major contribution to the rheologic properties of blood; alter adhesive properties under stress--including the stress of ischemia, enhancing their rheologic importance; and participate in endothelial injury, both acutely and chronically, by adhering to endothelium and damaging it with toxic oxygen compounds and proteolytic enzymes. Techniques newly developed or under development may allow us to refine the predictive value of the WBC count by combining it with measures of cell activation and/or activatability.

Lifestyle Effects on Hematopoiesis and Atherosclerosis

“…Despite our growing understanding of macrophages’ importance in atherosclerosis and blood monocyte levels’ impressive correlation with cardiovascular mortality 21, 22 , less is known about how monocyte production changes in cardiovascular disease. During atherosclerosis, monocyte levels increase progressively 23 , and more abruptly after acute myocardial infarction, which implies that acceleration of myelopoiesis associates with disease progression 24 .…”

Distant Effects of Experimental Renal Ischemia/Reperfusion Injury

“…Leukocytes have long been thought to be important in cardiac dysfunction after ischemia (10), and agents that block leukocyte function or localization protect against injury (11)(12)(13). An elevated white cell (WBC) count markedly increases the risk of acute myocardial infarction in humans (14), and removing WBC from cardioplegia solution improves myocardial function in stressed piglet hearts (15).…”

Lifestyle Factors and Coronary Artery Calcification

“…Atherosclerosis is a major cause of CHD and stroke. Monocyte-derived macrophages and other phagocytes are believed to contribute to vascular injury and atherosclerotic progression [18]. The plaque formation and calcium deposition is associated with an accumulation of microphages, smooth muscle cells, fibrosis, necrosis, and lipids in the artery [19].…”