[Effect of the two types of TNF-alpha on the biological functions of monocytic cell line U937].
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.
Xin
Li-Jun
LJ
Department of Immunology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030,China.
Li
Zhuo-Ya
ZY
Jiang
Xiao-Dan
XD
Feng
Wei
W
Xu
Yong
Y
Xiong
Ping
P
Gong
Fei-Li
FL
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
D016209:Interleukin-8; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D018799:Intercellular Adhesion Molecule-1