Section outline

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    What are those Y-shaped things floating around the ?
    ::那些Y形的东西是什么 漂浮在周围?

    They are antibodies , which are large . And they signal specific antigens for destruction. It does help that the antigens are usually attached to .
    ::它们是抗体,是巨大的。它们发出特定抗原的信号,要摧毁。这确实有助于抗体通常被附着。

    Humoral Immune Response
    ::应对不道德体重不足反应

    B cells are responsible for the humoral immune response . The humoral immune response takes place in and lymph and involves the production of antibodies. Antibodies are large Y-shaped proteins called immunoglobulins (Ig) that recognize and bind to antigens. In humans (and other mammals) there are five types of immunoglobulins: IgA, IgD, IgE, IgG, and IgM. Antibodies are produced by activated B cells.
    ::B细胞负责幽默性免疫反应,幽默性免疫反应发生在淋巴里和淋巴里,涉及抗体的生产,抗体是大型的Y形蛋白,叫做免疫球蛋白(Ig),识别抗原并与抗原结合,在人类(和其他哺乳动物)中,有五类免疫球蛋白:IgA、IgD、IgE、IgGG和IgM。抗体由活性B细胞产生。

    B Cell Activation
    ::B 细胞激活

    Naïve B cells are activated by an antigen in the sequence of events shown in  Figure . A B cell encounters its matching antigen and engulfs it. The B cell then displays fragments of the antigen on its surface. This attracts a helper T cell (which you will read about below). The helper T cell binds to the B cell at the antigen site and releases cytokines . Cytokines are chemical signals used to communicate between cells. Cytokines from the helper T cell stimulate the B cell to develop into plasma cells or memory cells.
    ::纳伊夫B细胞在图中显示的事件序列中被抗原激活。AB细胞遇到匹配的抗原并吞没它。B细胞然后在表面显示抗原的碎片。这吸引了一个帮助T细胞(下面将看到这一点)。帮助T细胞在抗原现场与B细胞捆绑并释放细胞。Cytokines是用于细胞之间通信的化学信号。从帮助T细胞中激发B细胞发展成等离子细胞或内存细胞。

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    After engulfing an antigen, a naïve B cell presents the antigen to a mature T cell. The T cell, in turn, releases cytokines that activate the B cell. Once activated, the B cell can produce antibodies to that particular pathogen.
    ::在吞没抗原后,天体细胞B向成熟的T型细胞展示抗原。T型细胞反过来释放出激活B型细胞的细胞。B型细胞一旦被激活,就可以产生抗体到该病原体。

    Plasma Cells and Antibody Production
    ::Plasma 细胞和抗体生产

    Plasma cells are activated B cells that secrete antibodies. They are specialized to act like antibody factories. Antibodies produced by plasma cells circulate in the blood and lymph. Each antibody recognizes and binds to a specific antigen, depending on the plasma cell that produced it and other factors. An antibody usually binds to an antigen at an antigenic determinant. The binding of an antibody to its matching antigen forms an antigen-antibody complex , as shown in  Figure . An antigen-antibody complex flags a pathogen or foreign cell for destruction by phagocytosis . The liver removes antigen-antibody complexes from the blood, and the spleen removes them from the lymph.
    ::等离子体细胞是分泌抗体的活性B细胞,它们专门作为抗体工厂。等离子细胞产生的抗体在血液和淋巴体中循环。每种抗体视产生血浆细胞的血浆细胞和其他因素而确认并粘合于特定的抗原。抗体通常在抗原的抗原决定因素与抗原结合。抗体与匹配抗原的抗体结合,形成抗原抗体复合体,如图所示。抗原复合体标记一种病原体或异体细胞,以便用发细胞进行破坏。肝脏从血液中除去抗原体综合体,脾脏将其从淋巴中除去。

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    An antibody molecule has an area that “fits” one particular antigen. This area is where the antigen binds to the antibody, creating an antigen-antibody complex.
    ::抗体分子有一个“适合”一种特定抗原的区域。这个区域是抗原与抗体结合的地方,它创造了一个抗原抗体综合体。

    Memory Cells
    ::内存单元格

    Whereas most plasma cells live just a few days, memory cells live much longer. They may even survive for the lifetime of the individual. Memory cells are activated B (or T) cells that retain a “memory” of a specific pathogen long after an infection is over. They help launch a rapid response against the pathogen if it invades the body in the future. Memory B cells remain in the lymph, ready to produce specific antibodies against the same pathogen if it shows up in body fluids again. Vaccination relies on the longevity of memory cells that remain in the lymph nodes .
    ::大多数等离子细胞只活几天,而内存细胞则活得更长,甚至可以活到个人一生。内存细胞在感染结束很久后仍保留特定病原体“模拟”的B(或T)细胞被激活。如果病原体今后侵入人体,它们有助于对病原体作出迅速反应。内存B细胞留在淋巴中,如果在体液中再次出现,可以产生针对同一病原体的特定抗体。接种取决于淋巴结中残留的内存细胞的寿命。

    Clonal Selection Theory
    ::克隆选择理论

    When a B cell recognizes antigens on the surface of a pathogen, it becomes activated and goes through clonal selection. Clonal selection is a process in which lymphocytes proliferate, producing clones of themselves that all target a specific antigen. The first group of newly cloned cells in the clonal selection of B cells are plasma cells. Each plasma cell can secrete up to 2,000 antibodies per second. The second group of cells produced are memory cells. Memory cells remain in the lymph nodes, awaiting second exposure to the same pathogen. If a second exposure occurs, memory cells initiate the secondary immune response , which is much quicker and stronger than the first. A second round of clonal selection ensues, and a larger number of antibodies are produced, often proving more effective against the pathogen.
    ::当 B 细胞在病原体表面识别抗原时,它就会被激活,并通过阴道选择。 阴道选择是一个过程, 淋巴细胞会扩散, 产生针对特定抗原的克隆体。 在B 细胞的阴道选择中, 第一组新克隆的细胞是血浆细胞。 每个血浆细胞可以每秒隐藏多达2,000个抗体。 产生的第二组细胞是记忆细胞。 内存细胞留在淋巴结中, 等待第二次接触同样的病原体。 如果第二次接触发生, 记忆细胞会引发次免疫反应, 其速度和强度都比第一次要快得多。 第二回合的血浆选择会发生, 并产生更多的抗体, 通常证明对病原体更有效。

      

     

    Summary
    ::摘要

    • B cell activation occurs after a B cell encounters a matching antigen.
      ::B型细胞在B型细胞遇到匹配的抗原后启动。
    • Helper T cells arrive and stimulate the B cell to develop into plasma cells or memory cells.
      ::帮助T细胞到达并刺激B细胞发展成等离子细胞或内存细胞。
    • An antigen-antibody complex flags a pathogen or foreign cell for destruction by phagocytosis. The liver removes antigen-antibody complexes from the blood, and the spleen removes them from the lymph.
      ::抗原抗体复合体会标出一种病原体或外来细胞,以便通过发细胞化而予以销毁。肝脏会从血液中去除抗原抗体复合体,脾脏会将其从淋巴中去除。
    • Memory cells live much longer in the body and are ready to launch a rapid response if the same pathogen appears again.
      ::内存细胞在体内活得更长,如果同一病原体再次出现,随时可以作出快速反应。

    Review
    ::回顾

    1. What role do helper T cells play in the humoral immune response?
      ::帮助T细胞在幽默的免疫反应中扮演什么角色?
    2. What happens after the antibody attaches to the antigen?
      ::抗体附着抗原后会怎样?
    3. If your body encounters a pathogen for a second time, which cells quickly respond?
      ::如果你的身体第二次遇到病原体 哪个细胞会迅速反应?