吞噬體(phagosome)也稱為吞噬小體,是一種在胞吞作用中在被吞噬物質周圍形成的囊泡,這種囊泡由細胞膜細胞內凹陷產生。吞噬體是一種在免疫過程中常見的細胞結構,入侵機體內的病原微生物可在吞噬體中被殺滅、消化。在成熟過程中吞噬體需與溶酶體融合,生成兼具隔離與分解異己物質能力的吞噬溶酶體,這種經兩種囊泡融合而成的新囊泡只曾在動物細胞中發現。

病原體躲避分解

一些通過胞吞作用進入病原體細菌能躲避分解,其中一部分(如考克斯氏體屬細菌)可以在融合後的吞噬溶酶體中繼續繁殖[1]而另一部分(如立克次氏體屬細菌)則能通過破壞吞噬體膜在吞噬體與溶酶體融合之前逃逸到細胞質基質中。[2]

包括結核分支桿菌Mycobacterium tuberculosis[3] [4]鳥副結核分支桿菌Mycobacteria avium paratuberculosis[5]的許多分支桿菌屬細菌還可以操縱寄主巨噬細胞,使含有亞硝酸的溶酶體不能與吞噬體融合成吞噬溶酶體。這種在成熟過程中被阻斷的吞噬體反而會成為其中的病原體繁殖的適宜環境。[6]

參考文獻

  1. ^ Hackstadt T and Williams J C "Biochemical stratagem for obligate parasitism of eukaryotic cells by Coxiella burnetii." Proc Natl Acad Sci U S A. 1981 May; 78(5): 3240–3244.
  2. ^ Winkler H H "Rickettsia Species (As Organisms)" Annual Review of Microbiology Vol. 44: 131-153
  3. ^ MacMicking, JD; Taylor, GA; McKinney, JD. Immune control of tuberculosis by IFN-γ –inducible LRG-47. Science. 2003, 302: 654–659. PMID 14576437. 
  4. ^ Vandal, OH; Pierini, LM; Schnappinger, D; Nathan, CF; Ehrt, S. A membrane protein preserves intrabacterial pH in intraphagosomal Mycobacterium tuberculosis. Nat Med. August 2008, 14 (8): 849–854. PMID 18641659. 
  5. ^ Kuehnel, MP; Goethe R, Habermann A, Mueller E, Rohde M, Griffiths G, Valentin-Weigand P. Characterization of the intracellular survival of Mycobacterium avium ssp. paratuberculosis: phagosomal pH and fusogenicity in J774 macrophages compared with other mycobacteria.. Cell Microbiol. August 2001, 3 (8): 551–566. PMID 11488816. 
  6. ^ Tessema, MZ; Koets AP, Rutten VP, Gruys E. How does Mycobacterium avium subsp. paratuberculosis resist intracellular degradation?. Vet Q. 2001 month=November, 23 (4): 153–162. PMID 11765232. 

外部連結

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