SECRETION OF CYTOKINES BY NATURAL-KILLER-CELLS PRIMED WITH INTERLEUKIN-2 AND STIMULATED WITH DIFFERENT LIPOPROTEINS

Natural killer (NK) cells were shown to secrete differentially interle ukins (IL), IL-1 alpha, IL-1 beta, IL-2, IL-8, interferon-gamma (IFN-g amma), tumour necrosis factor-alpha (TNF-alpha), granulocyte-macrophag e colony-stimulating factor (GM-CSF), and leukaemia inhibitory factor (LIF) upon stimulation with optimal concentrations of chylomicrons (CM ), very-low-density lipoprotein (VLDL), low-density lipoprotein (LDL), high-density lipoprotein (HDL) or acetyl-modified low-density lipopro tein (AcLDL). CM, VLDL, LDL and AcLDL induced LIF secretion which was absent in non-stimulated cells. CM, VLDL, and LDL did not affect IL-lc r secretion. CM stimulated IL-8 > TNF-alpha > IL-1 alpha > IL-2 = IFN- gamma, and decreased seventeenfold GM-CSF secretion. VLDL stimulated I L-8 secretion > IL-1 alpha = IL-2 > IFN-gamma > TNF-alpha and decrease d fivefold GM-CSF secretion. LDL stimulated IL-8 secretion > IL-1 alph a > IL-2 = IFN-gamma, it did not modify TNF-alpha and inhibited five h undred-fold GM-CSF secretion. HDL stimulated IL-2 secretion = IFN-gamm a > IL-8, it decreased GM-CSF secretion > IL-1 alpha > IL-1 beta > TNF -alpha without affecting LIF. AcLDL stimulated IL-8 secretion > TNF-al pha > IL-1 alpha > IL-2 = IFN-gamma = IL-1 beta, and decreased GM-CSF secretion eightfold. When NK cells were primed with 10, 100 or 500 IU/ ml of IL-2 before the addition of lipoproteins, a decrease in the secr etion of cytokines was observed as compared with cells primed with IL- 2 only. Differences in cytokine secretion were observed among the dive rse type of lipoproteins used for cell stimulus. Thus, lipoproteins ma y condition NK cytokine secretion and cell activation.