The hemolytic activity of homocysteine is increased by the activated polymorphonuclear leukocytes.

Homocysteine is an accepted risk factor when its plasma level exceeds the physiological upper limit of 12 mumol/L. We found in vitro that homocysteine is able to lyse the erythrocytes (RBCs) at higher concentrations than 15 mumol/L only when activated polymorphonuclear leukocytes (PMNL) are present. The hemolytic effect of homocysteine was higher in RBCs obtained from cardiac catheterized patients with 100% stenosis of the coronary arteries. Homocysteine was also able to increase the activation in vitro of PMNLs triggered by opsonized zymosan. The hemolytic action of homocysteine was found to be dependent on the ratio of PMNLs to RBCs. This relationship may help to explain the great individual variations in the hemolytic activity noticed in blood obtained from cardiac catheterized patients, and also may explain the mild anemia in some patients suffering from cardiovascular disease.