ABSTRACT
Objective To investigate the distribution of T follicular helper(Tfh)cell subsets in hepa-titis B patients at different immune stages and to clarify the relationships between the level of CXCL13 and the distribution of Tfh cell subsets. Methods Flow cytometry analysis was performed to detect the distribution of Tfh cells. Enzyme-linked immunosorbent assay(ELISA)was performed to measure the levels of CXCL13 in ser-um samples collected from hepatitis B patients. RT-PCR and Western blot assay were used to analyze the expres-sion of CXCL13 in HepG2 and HepG2. 2. 1. 5 cells. Results The percentages of Tfh1 cells were significantly up-regulated at the immune activation(IA)stage,while those of Tfh2 cells were significantly raised at the im-mune tolerance(IT)stage. The percentages of Tfh17 cells in patients at the stage of IT were similar to those in patients at the stage of IA,but were higher than those in responders with HBsAg seroconversion(RP)or healthy controls(HC). The expression of CXCL13 was positively correlated with the percentage of Tfh2 cells. More over,hepatitis B virus(HBV)enhanced the expression of CXCL13 at both transcriptional and translational lev-els. Conclusion HBV might up-regulate the percentage of Tfh2 cells through promoting the expression of CXCL13,which resulted in the induction of immune tolerance. Elucidating the functions of Tfh1,Tfh2 and Tfh17 cells and understanding the type conversion mechanism among the three subsets are important for further researches on HBV-induced immunosuppression.
ABSTRACT
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-gamma (IFN-gamma), and tumor necrosis factor-alpha (TNF-alpha) to induce the production of human interleukin-15 (hIL-15) and IL-15 receptor (IL-15Ralpha) 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-gamma and TNF-alpha. 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-15Ralpha was detected on the surface of HUVECs by FACS after IFN-gamma and TNF-alpha stimulation, whereas Western blotting revealed that the elevated expression on surface IL-15Ralpha was not due to the increased protein expression. The conclusion demonstrated from our results is that IFN-gamma and TNF-alpha play an important role in regulating the expression of IL-15 and IL-15Ralpha on the surface of HUVECs.
ABSTRACT
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.