ABSTRACT
Human interleukin-15 (hlL-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-ct (TNF-α) to induce the production of human interleukin-15 (hlL-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. lntracellular IL-15 protein was visualized by fluorescence microscopy, whereas the expres-sion 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-γ 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-γ and TNF-α play an important role in regulating the expres-sion of IL-15 and IL-15Rα on the surface of HUVECs.