两型TNF-α对单核细胞系U937细胞功能的影响

目的：比较两型TNF—α对单核细胞系U937细胞功能的影响，以探讨跨膜型TNF—α在炎症中的作用。方法：通过吞噬、RT-PCR、Western blot及FACS等方法，比较两型TNF—α对U937细胞生物学功能(包括吞噬、细胞因子mRNA、胞质IκB—α及ICAM—1表达等)的影响。结果：分泌型TNF—α可明显促进U937细胞吞噬功能，使TNF—α、IL—1β及IL—8 mRNA积累增加，促进胞质IκB—α降解及提高黏附分子ICAM—1的表达；而跨膜型TNF—α对上述U937细胞的生物学功能则无明显影响：当二者联用时，跨膜型TNF—α与分泌型TNF—α亦无协同作用。结论：分泌型TNF—α对U937细胞具有明显地激活作用；而跨膜型TNF—α则无影响，提示两型TNF—α在炎症过程中的作用不同。

Effect of the two types of TNF-α on the biological functions of monocytic cell line U937

AIM: 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. CONCLUSION: 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.