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三種巨噬細胞(我只是做翻譯)



It used to be easy.
本來事情很單純的



In the old days (~8 years ago),
以前 



activated macrophages were simply defined as cells that secreted inflammatory mediators and killed intracellular pathogens.
巨噬細胞被認為只會分泌發炎介質還有殺掉細胞內的病源體


Things are becoming progressively more complicated in the world of leukocyte biology.
近來發現

Activated macrophages may be a more heterogenous group of cells than originally appreciated,
被活化的巨噬細胞分成了幾類,跟原來預期的不同 


with different physiologies and performing distinct immunological functions.
他們有不同的生理特性,並且有特殊的免疫功能。 


The first hint of this heterogeneity came with the characterization of the "alternatively activated macrophage" .
第一類要說的是 alternatively activated macrophage


The exposure of macrophages to interleukin (IL)-4 or glucocorticoids induced a population of cells that up-regulated certain phagocytic receptors but failed to produce nitrogen radicals and as a result, were relatively poor at killing intracellular pathogens.
只要把巨噬細胞暴露在其他細胞所製造的IL-4或是葡萄糖皮質素下就會產生
這種細胞雖然提升吞噬受器的數目,但是失去製造自由基的功能
暗示這種巨噬細胞去除病源體的能力很爛


Recent studies have shown that these alternatively activated cells produce several components involved in the synthesis of the extracellular matrix (ECM) , suggesting their primary role may be involved in tissue repair rather than microbial killing.
最近的研究指出,這種特殊的活化細胞,會合成一些胞外物質
表示他們的角色可能是以組織修復為主


It turns out that the name alternatively activated macrophage may be unfortunate for a few reasons.
叫他 alternatively activated macrophage,是因為以下原因


First, although these cells express some markers of activation, they have not been exposed to the classical, activating stimuli, interferon-{gamma} (IFN-{gamma}) and lipopolysaccharide (LPS).
第一,雖然這些細胞表現一些可被活化的標記,但是他們沒有被暴露在一般激發巨噬細胞的物質中。



[ 這些物質包括 ( IFN-gamma、LPS ) ]
Second, and more importantly, the name implies that this is the only other way to activate a macrophage.
第二,這個名字暗示她是特殊路徑所活化的。


Recent studies suggest that this may not be the case. Exposure of macrophages to classical activating signals in the presence of immunoglobulin G (IgG) immune complexes induced the production of a cell type that was fundamentally different from the classically activated macrophage.
最近研究指出,把巨噬細胞暴露在免疫複合物(Ag-Ab complex)中,可以產生另外一種的活化細胞。


These cells generated large amounts of IL-10 and as a result, were potent inhibitors of acute inflammatory responses to bacterial endotoxin [4 ].
這種活化的巨噬細胞,會釋出IL-10,IL-10主要是抑制細菌所造成的發炎反應。 


These activated macrophages have been called type 2-activated macrophages [5 ] because of their ability to induce T helper cell type 2 (Th2) responses that were predominated by IL-4 [6 ], leading to IgG class-switching by B cells.
這種活化的巨噬細胞被稱為type 2-activated macrophages ,他們可以活化Th 2 細胞,
也可以造成B 細胞的抗體的重組---------->走向體液免疫。

 
Thus, at this time, there appears to be at least three different populations of activated macrophages with three distinct biological functions. The first and most well described is the classically activated macrophage whose role is as an effector cell in Th1 cellular immune responses. The second type of cell, the alternatively activated macrophage, appears to be involved in immunosuppression and tissue repair.The most recent addition to this list is the type 2-activated macrophage, which is anti-inflammatory and preferentially induces Th2-type humoral-immune responses to antigen.

所以現在巨噬細胞有三種型態、三種功能啦~


第一種是最為人所熟知的classically activated macrophage,主要誘導Th1細胞免疫
第二種是alternatively activated macrophage,主要會壓制免疫系統,但是幫助組織修復
第三種是type 2-activated macrophage,壓制發炎,並且誘導Th2體液免疫




 Together, these three populations of cells may form their own regulatory network to prevent a well-intentioned immune response from progressing to immunopathology.

這三種細胞之間會互相調控,去避免完全的某種免疫反應
(例如100%的體液免疫、或是100%的細胞免疫)


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