株落失能

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株落失能英语:Clonal anergy)是一個免疫學名詞。描述的是周邊淋巴球對於外來物質失去產生免疫反應的能力,而導致耐受性。失能的淋巴球株落將無法對於特定的抗原產生免疫反應,通常此抗原為自身抗原。株落失能為誘導產生抗原耐受性的方法之一(另外為clonal deletion英语clonal deletion免疫系统),以避免免疫系統攻擊自身抗原,而導致自體免疫疾病[1]

機制[编辑]

此現象最早是Gustav Nossal英语Gustav Nossal於B細胞上面發現,並被命名為「株落失能」。此株B細胞仍然存活,但已經失去產生免疫反應的功能。後來Ronald Schwartz英语Ronald SchwartzMarc Jenkins英语Marc Jenkins也在T細胞身上發現了此現象。許多病毒(如HIV)和細菌(如痲瘋桿菌)會利用此系統誘導免疫系統對於這些病原菌產生耐受性。[2]

就細胞層及來說,株落失能象徵的是免疫細胞無法對於目標進行完整的反應。在免疫系統中,在血液中循環的淋巴球是抵擋病毒細菌,和寄生蟲的基本防線。但在這些淋巴球中,真正可以辨識特定抗原的實在少之又少。當受到感染時,這些具有辨識抗原能力的細胞會迅速活化增生,這種現象稱為「株落增殖」(clonal expansion),使個體可以快速產生免疫反應

Such immune response is anticipatory and its specificity is assured by pre-existing clones of lymphocytes, which expand in response to specific antigen (process called "clonal selection"). This specific clonal army then combats the pathogen until the body is free of the infection. Following clearance of the infection, the clones that are no longer needed die away naturally.

However, a small number of the body's army of lymphocytes are able to react with proteins that are normally present in a healthy body. The clonal expansion of those cells can lead to autoimmune diseases, wherein the body attacks itself. In order to prevent this process, lymphocytes possess an intrinsic quality-control mechanism. This machinery shuts down the lymphocytes' ability to expand, if the trigger for the expansion turns out to be the body's own protein. T-cell anergy can arise when the T-cell does not receive appropriate co-stimulation in the presence of specific antigen recognition.[2] B-cell anergy can be induced by exposure to soluble circulating antigen, and is often marked by a downregulation of surface IgM expression and partial blockade of intracellular signaling pathways.[2]

臨床意義[编辑]

株落失能可以用於減緩器官移植後所產生的排斥現象。且相較於其他免疫抑制劑副作用更低。

另外也可能可以用於治療自體免疫疾病,如糖尿病風濕性關節炎,和多發性硬化症[1],也可以用於治療過敏[3]。反之,如果可以成功抑制身體對於腫瘤細胞的株落失能反應,則可以再次啟動身體對於腫瘤的免疫作用。[4]

試驗[编辑]

一般檢驗細胞免疫的方法為皮下英语intradermal測試,有「Multitest Mérieux」和 「CMI Multitest系統」兩種。

It is an intradermal test of skin reactivity (similar to tuberculin tests) in which a control (glycerol) is used with seven antigens of bacterial or fungal origin (tetanus toxoid, tuberculin, diphtheria, streptococcus, candida, trichophyton, and proteus). In this test reactions are categorized according to the number of antigens provoking a response and the summed extent of the skin response to all seven antigens. Here anergy is defined as a region of skin reactivity of 0–1 mm, hypoergy as a reaction of 2–9 mm in response to fewer than three antigens, normergic as a reaction of 10–39 mm or to three or more antigens, and hyperergy for a reaction of 40 mm or more.[5][6][7]

參考文獻[编辑]

  1. ^ 1.0 1.1 Schwartz, Ronald H. T Cell Anergy. Scientific American. 1993, 269 (2): 61–71. 
  2. ^ 2.0 2.1 2.2 Janeway, Charles; Travers, Paul; Walport, Mark; Shlomchik, Mark. Immunobiology; Fifth Edition. New York and London: Garland Science. 2001. ISBN 0-8153-4101-6. 
  3. ^ Rolland, J; O'Hehir, R. Immunotherapy of allergy: anergy, deletion, and immune deviation. Curr Opin Immunol. Dec 1998, 10 (6): 640–5. doi:10.1016/s0952-7915(98)80082-4. 
  4. ^ Saibil, Samuel D.; Deenick, Elissa K.; Ohashi, Pamela S. The sound of silence: modulating anergy in T lymphocytes. Current Opinion in Immunology. 2007, 19 (6): 658–664. PMID 17949964. doi:10.1016/j.coi.2007.08.005. 
  5. ^ Müller, Nicole; Schneider, Th; Zeitz, M; Marth, Th. Whipple's disease: new aspects in pathogenesis and diagnoses (PDF). Acta Endoscopica. 2001, 31: 243–253. 
  6. ^ Spornraft, P.; Fröschl, M.; Ring, J.; Meurer, M.; Goebel, F.-D.; Ziegler-Heitbrock, H.W.L.; Riethmüller, G.; Braun-Falco, O. T4/T8 ratio and absolute T4 cell numbers in different clinical stages of Kaposi's sarcoma in AIDS (PDF). British Journal of Dermatology. 1988, 139: 1–9. (原始内容 (PDF)存档于2011-06-11). 
  7. ^ De Flora, S.; Grassi, C.; Carati, L. Attenuation of influenza-like symptomatology and improvement of cell-mediated immunity with long-term N-acetylcysteine treatment (PDF). Eur Respir J. 1997, 10 (7): 1535–1541. PMID 9230243. doi:10.1183/09031936.97.10071535. 

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