EFFECTS OF HUMAN LOW-DENSITY LIPOPROTEINS ON SUPEROXIDE PRODUCTION BYFORMYL-METHIONYL-LEUCYL-PHENYLALANINE ACTIVATED POLYMORPHONUCLEAR LEUKOCYTES

Neutrophils play a major role in the host defence by producing reactiv e oxygen species. These products are liberated by activated cells and are known to cause endothelial cell injury and damage. The present stu dy shows that low-density lipoproteins increase superoxide anion produ ction by twofold in polymorphonuclear leukocytes stimulated by formyl- Met-Leu-Phe in vitro. Moreover, LDL induced a large increase in phosph oinositides and cytosolic-free calcium. Data from experiments performe d on neutrophils treated with pertussis toxin, staurosporine, proprano lol or niflumic acid suggest that modulation of phospholipase D and A( 2) activities could be involved in the modification by LDL of leukocyt e response to formyl-Met-Leu-Phe. LDL lipid moiety could play a key ro le in their action on polymorphonuclear functions because cholesterol was exchanged between lipoproteins and cells that can modify membrane fluidity and interact with the formyl-Met-Leu-Phe receptor.