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Innate immunity (also called natural or native immunity ) provides the early line of defen against microbes. it consists of cellular and biochemical defen mechanisms that are in place even before infection and are poid to respond rapidly to infections .The mechanisms react to microbes and to the products of injured cells . and they respond in esntially the same way to repeated infections .The principal components of innate immunity are (1) physical and chemical barriers. such as epithelia and antimicrobial chemicals Produced at epithelial surfaces: (2) phagocytic cells (neutrophils, macrophages) , dendritic cells. and natural killer (NK) cells: (3) blood proteins, including members of the complement system and other mediators of inflammation; and (4) proteins called cytokines that regulate and coordinate many of the activities of the cells of innate immunity. The mechanisms of innate immunity are specific for structures that are common to groups of related microbes and may not ,distinguish fine differences between microbes.
固有免疫（又叫自然免疫或者先天性免疫）为抵制微生物提供了早期的天然防线。它有细胞
和生化机制构成，他们甚至在感染之前就已经开始运转，随时准备迅速应对感染。这些机制对微生物和受损细胞的产生做出反应，也已基本相同的方式应对重复感染。固有免疫主要成分是1.物理和化学屏障，比如上皮组织和上皮表层产生的抗菌化学物。2.噬菌细胞（嗜中性粒细胞，巨噬细胞），树突状细胞和自然杀伤细胞。3.血蛋白，包括补体系统的成分和其他的炎症介质。4.一种叫做细胞因子的蛋白质能够调节和协调固有免疫的细胞活动。固有免疫机制是专门针对成组的相关联微生物共同拥有的结构的，他们可能无法分辨为生物之间的细小差别。
In contrast to innate immunity. there are other immune respons that stimulated by exposure to infectious agents and increa in magnitude and defensive capabilities with each successive exposure to a particular microbe Becau this form of immunity develops as a respon to infection and adapts to the infection. it is called adaptive immunity. The defining characteristics of adaptive immunity are exquisite specificity for distinct molecules and an ability to "remember" and respond more vigorously to repeated exposures to the same microbe .The adaptive immune邮箱号怎么申请
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中秋节在什么时候system is able lo recognize and react to a large number of microbial and nonmicrobial substances. In addition. it has an extraordinary capacity to distinguish between different , even cloly related, microbes and molecules, and for this reason it IS also called specific immunity. It is also sometimes called acquired immunity. to emphasize that potent protective respons are “acquired" by experience .The main components of adaptive immunity are cells called lymphocytes and their creted products. such as antibodies. Foreign substances that induce specific immune respons or are recognized by Symphocytes or antibodies are called antigens. 与固有免疫相比，因接触感染因子而被激活的其它的免疫反应会因为与某一种微生物的反复接触而体积增大和防御能力增强。因为这种形式的免疫会随着对感染的反应而发展和调整，因此叫做适应性反应。适应性免疫的明确特征是对不同的分子有敏锐的特异性，他有记忆的功能能够对相同微生物的重复感染做出更加激烈的应答。适应性免疫系统能够识别，并对大量的微生物和非微生物产生应答。此外，他有一种卓越的能力，能够区别不同的甚至是关系紧密的微生物和分子。正因为如此，它有被成为特异性免疫，有时候也叫后天免疫，是为了强调这种强大的保护应答是因为（不断）接触而获得的。适应性免疫的主要成分是淋巴细胞和他们的分泌物比如抗体。诱发特异性免疫或者被淋巴细胞或抗体识别的外来物质被称为抗原。
Mechanisms for defending the host against microbes are prent in some form in all multicellular organisms . The mechanisms constitute innate immunity The more specialized defen mechanisms that constitute adaptive immunity are found in vertebrates only. Two functionally similar but molecularly distinct adaptive immune systems developed at different times in evolution. About 500 million years ago, jawless fish. such as lampreys and hagfish. developed a unique immune system containing diver lymphocyte-like cells that may function like lymphocytes in more advanced species and even responded to immunization The antigen receptors on the cells were variable leucine-rich receptors that were capable of recognizing many antigens but were distinct from the antibodies and T cell receptors appeared later in evolution. Most of the components of the adaptive immune system, including lymphocytes with highly diver antigen receptors, antibodies. specialized lymphoid tissues, evolved coordinately within a short time in jawed vertebrates (e. g. , sharks). about 360 million years ago. The immune system has become increasingly specialized with evolution .
保护诉诸抵制微生物的机制在所有的多细胞生物中以某种形式存在着。这些机制构成了
情何归固有免疫。构成适应性免疫的更加特异的防御机制只有在脊椎动物身上才有。在进化过程中两种功能相似但是分子相异的适应性免疫系统在不同时期得到了发展。大约5亿年前，八目鳗和盲鳗这些无颚鱼进化了一种独一无二的免疫系统，它有各种像淋巴细胞一样的细胞，能在更加高级的物种里像淋巴细胞一样发挥作用，甚至能对免疫应答。这些细胞上的抗原受体是多变的亮氨酸受体，能够识别许多的抗原，但是却和后来进化过程中出现的抗体和T细胞不同。适应性免疫系统的大多数成分，包括带有高度多样化抗原受体的淋巴细胞，抗体和特异的淋巴组织，是在3亿6千万年前在有颚脊椎动物（比如鲨鱼）中短时间里协调进化的。免疫系统也在进化过程中日益特异化。
Innate and adaptive immune respons are components of an integrated system of host defen in which numerous cells and molecules function cooperatively. The mechanisms of innate immunity provide effective initial defen against infections. However. many pathogenic microbes have evolved to resist innate immunity. their elimination requires the more powerful mechanisms of adaptive immunity .There are many connections between the Innate and adaptive immune systems. The innate immune respon to microbes stimulates adaptive immune respons and influence natu
re of the adaptive respons Converly. adaptive immune respons often work by enhancing the protective mechanisms of innate immunity, making capable of effectively combating pathogenic microbes. 小月河
