title: [Effect of the two types of TNF-alpha on the biological functions of monocytic cell line U937].
abstract: OBJECTIVE
  To compare the effect of the two types of TNF-alpha, transmembrane TNF-alpha (TM-TNF-alpha) and secreted TNF-alpha (sTNF-alpha) on the biological functions of monocytic cell line U937 so as to explore the role of TM-TNF-alpha in inflammation.
  
  
  METHODS
  Effect of the two types of TNF-alpha on the functions of U937 cells, such as phagocytosis, accumulation of cytokines' mRNA, the level of cytoplasmic IkappaB-alpha and expression of ICAM-1, was compared by phagocytosis, RT-PCR, Western blot and FACS.
  
  
  RESULTS
  sTNF-alpha was found to be able to promote markedly phagocytosis by monocytic U937 cells, enhance the mRNA accumulation of cytokines, such as TNF-alpha, IL-1beta and IL-8 mRNA, induce the degradation of IkappaB-alpha and the expression of adhesion molecule ICAM-1; while TM-TNF-alpha was shown to have no effect on the functions above of U937 cells. Furthermore, it seemed TM-TNF-alpha did not have a synergic action with sTNF-alpha when U937 cells was treated with both types of TNF-alpha.
  
  
  CONCLUSIONS
  The data above shows that sTNF-alpha can activate U937 cells, while TM-TNF-alpha has no influence. It suggests that the two types of TNF-alpha may play the different role in inflammation.
authors.affiliation: Department of Immunology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030,China.
authors.forename: Li-Jun
authors.initials: LJ
authors.lastname: Xin
authors.forename: Zhuo-Ya
authors.initials: ZY
authors.lastname: Li
authors.forename: Xiao-Dan
authors.initials: XD
authors.lastname: Jiang
authors.forename: Wei
authors.initials: W
authors.lastname: Feng
authors.forename: Yong
authors.initials: Y
authors.lastname: Xu
authors.forename: Ping
authors.initials: P
authors.lastname: Xiong
authors.forename: Fei-Li
authors.initials: FL
authors.lastname: Gong
mesh_terms: D006801:Humans; D018799:Intercellular Adhesion Molecule-1; D016209:Interleukin-8 / Q000378:metabolism; D009000:Monocytes / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics; D020298:U937 Cells
chemical_list: D016209:Interleukin-8; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D018799:Intercellular Adhesion Molecule-1