Secretion of cytokines by natural killer cells primed with interleukin-2 and stimulated with different lipoproteins

Abstract

Natural killer (NK) cells were shown to secrete differentially interleukins (IL), IL-1α, IL-1β, IL-2, IL-8, interferon-γ (IFN-γ), tumour necrosis factor-α (TNF-α), granulocyte-macrophage 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 lipoprotein (AcLDL). CM, VLDL, LDL and AcLDL induced LIF secretion which was absent in non-stimulated cells. CM, VLDL, and LDL did not affect IL-1α secretion. CM stimulated IL-8 > TNF-α > IL-1α > IL-2 = IFN-γ, and decreased seventeenfold GM-CSF secretion. VLDL stimulated IL-8 secretion > IL-1α = IL-2 > IFN-γ > TNF-α and decreased fivefold GM-CSF secretion. LDL stimulated IL-8 secretion > IL-1α > IL-2 = IFN-γ, it did not modify TNF-α and inhibited five hundredfold GM-CSF secretion. HDL stimulated IL-2 secretion = IFN-γ > IL-8, it decreased GM-CSF secretion > IL-1α > IL-1β > TNF-α without affecting LIF. AcLDL stimulated IL-8 secretion > TNF-α > IL-1α > IL-2 = IFN-γ = IL-1β, 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 secretion of cytokines was observed as compared with cells primed with IL-2 only. Differences in cytokine secretion were observed among the diverse type of lipoproteins used for cell stimulus. Thus, lipoproteins may condition NK cytokine secretion and cell activation.