Expression of interleukin-15 and its receptor on the surface of stimulated human umbilical vein endothelial cells

Summary： Human interleukin-15 （hIL-15） is an important cytokine to activate endothelial cells and can be regulated by many other cytokines. The aim of this study is to examine the ability of interferon-γ （IFN-γ）, and tumor necrosis factor-or （TNF-α to induce the production of human interleukin-15 （hIL-15） and IL-15 receptor （IL-15Rα by human umbilical vein endothelial cells （HUVECs）. The data are summarized as follows： 1. Northern blot revealed that IL-15 mRNA was up-regulated by IFN-γ and TNF-α 2. Intracellular IL-15 protein was visualized by fluorescence microscopy, whereas the expression of IL-15 on the surface of HUVECs was detected by fluorescence activated cell sorting （FACS）, and no detectable IL-15 in the medium was verified by ELISA. 3. IL-15Rα was detected on the surface of HUVECs by FACS after IFN-α and TNF-α stimulation, whereas Western blotting revealed that the elevated expression on surface IL-15Rα was not due to the increased protein expression. The conclusion demonstrated from our results is that IFN-α and TNF-α play an important role in regulating the expression of IL-15 and IL-15Rα on the surface of HUVECs.     

Modulation of Interleukin-15-induced Suppression of Human Neutrophil Apoptosis by TNFα

Human interleukin-15(IL-15) is a proinflammatory cytokine to suppress neutrophil apoptosis,which is a potential therapeutic agent.The modulatory effect of TNFα was investigated in IL-15-induced suppression of human neutrophil apoptosis.TNFα was shown to reverse the ability of IL-15 to delay neutrophil apoptosis within certain time course.Moreover,this reverse effect by TNFα might be associated with a reduction of the expression of the anti-apoptotic Bcl-Xl protein detected by Western blotting.It is concluded that TNFα can be used to modulate IL-15-induced suppression of neutrophil apoptosis within certain time course.