Effects of plasma lipoproteins on the production of superoxide anion by human polymorphonuclear leukocytes in vitro

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Abstract
Polymorphonuclear leukocytes (PMN) generate highly reactive oxygen derived free radicals that may cause lipoprotein lipid oxidation and so contribute to the pathogenesis of atherosclerosis. On the other hand it has been shown that lipoproteins can alter cell functions in vitro. We therefore studied the effects of atherogenic lipoproteins, VLDL and LDL, on the production of superoxide anion by human PMN in the presence or absence of formyl-methionyl-leucyl-phenylalanine (fMLP). VLDL and LDL stimulate PMN superoxide production and potentialize PMN stimulation by fMLP. The lipid moiety of the lipoproteins might be mainly involved in these effects. The binding of radio-labelled fMLP to its specific membrane receptor was significantly enhanced in the presence of VLDL and only slightly in the presence of LDL. The study of the signal transduction suggests that modulation of phospholipase D and A2 activities could be involved in the modification by LDL of PMN response to fMLP.