Changes in IL-8 release and intracellular content in DMSO-differentiated HL-60 cells after treatment with 4-hydroxynonenal

4-Hydroxynonenal (HNE), a chemotactic aldehyde produced by lipid peroxidation, has been shown to trigger exocytosis in HL-60 cells induced to differentiate toward the granulocytic cell line by DMSO. In this work we studied HNE effects on the intracellular content of IL-8 and its release in DMSO-differentiated HL-60 cells. Cell incubation at 37 degrees C in the presence of 0.1 microM HNE induced a significant increase of IL-8 release after 30 min; the degree of HNE-induced IL-8 secretion became quite strong after 1 h, whereas the intracellular content showed no statistically significant changes. By contrast, 1 microM HNE induced a low decrease of the chemokine release; however, the used HNE concentrations failed to increase the release of lactate dehydrogenase (LDH), a test used to assay cell viability. The addition of 0.1 microM IL-8 to DMSO-differentiated HL-60 cells induced a strong increase of exocytosis, measured by beta-glucuronidase secretion. Exocytosis stimulation by IL-8 was much higher than that given by the aldehyde; the addition of various HNE concentrations to cells incubated in the presence of IL-8 decreased the secretion given by the cytokine alone. However, HNE-induced exocytosis was likely to be a direct action of the aldehyde and was not mediated through the stimulation of IL-8 release since HNE was unable to modify IL-8 secretion during the short time of 10 min used in the exocytosis assay.