The development of the mucosal immune system pre- and post-weaning: balancing regulatory and effector function
The development of the mucosal immune system pre- and post-weaning: balancing regulatory and effector function
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DOI：
10.1079/pns2005452
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发表时间：
2005-11-01
影响因子：
7
通讯作者：
Stokes, C
中科院分区：
文献类型：
--
作者：
Bailey, M;Haverson, K;Stokes, C
粘膜免疫系统履行防御可能穿过脆弱的表面上皮进入的潜在病原体的主要功能。然而，肠道免疫系统的第二功能是区分病原体相关抗原和“无害”抗原，表达对前者的主动应答和对后者的耐受性。免疫应答的控制似乎是一个主动过程，涉及伊加和调节性和/或调节性T淋巴细胞的局部产生。两个重要的时期，最大暴露于新的抗原发生在年轻的动物，出生后立即和断奶。在这两种情况下，由于新的饮食和新的菌株和细菌种类的定植，肠内容物的抗原组成可能突然发生变化。人类生活方式和动物饲养的变化，导致断奶变得比以前在进化中更加突然，增加了必须同时由新生儿评估的抗原的数量。因此，出生和断奶可能代表对病原体和无害的饮食和肠道抗原的适当反应的发展中的危险和关键控制点。新生儿出生时粘膜免疫系统相对不发达。出生时，这种因子可能会阻止主动免疫反应的表达和耐受性的发展。然而，肠道植物群的定殖以抗原特异性和非特异性方式扩大粘膜免疫系统。在断奶时，可以检测到对喂食蛋白质的抗体，表明对喂食蛋白质的主动免疫应答。有人提出，在正常条件下，粘膜免疫系统对外来抗原产生主动应答的能力与控制和调节这种应答的能力同时发展。当免疫系统的一个或另一个手臂发育不适当时，就会出现问题，导致对无害食物蛋白质的不适当的效应反应（过敏）或对病原体的反应不足（疾病易感性）。
The mucosal immune system fulfils the primary function of defence against potential pathogens that may enter across vulnerable surface epithelia. However, a secondary function of the intestinal immune system is to discriminate between pathogen-associated and 'harmless' antigens, expressing active responses against the former and tolerance to the latter. Control of immune responses appears to be an active process, involving local generation of IgA and of regulatory and/or regulated T lymphocytes. Two important periods of maximum exposure to novel antigens occur in the young animal, immediately after birth and at weaning. In both cases the antigenic composition of the intestinal contents can shift suddenly, as a result of a novel diet and of colonisation by novel strains and species of bacteria. Changes in lifestyles of man, and husbandry of animals, have resulted in weaning becoming much more abrupt than previously in evolution, increasing the number of antigens that must be simultaneously evaluated by neonates. Thus, birth and weaning are likely to represent hazard and critical control points in the development of appropriate responses to pathogens and harmless dietary and commensal antigens. Neonates are born with relatively undeveloped mucosal immune systems. At birth this factor may prevent both expression of active immune responses and development of tolerance. However, colonisation by intestinal flora expands the mucosal immune system in antigen-specific and non-specific ways. At weaning antibody to fed proteins can be detected, indicating active immune responses to fed proteins. It is proposed that under normal conditions the ability of the mucosal immune system to mount active responses to foreign antigens develops simultaneously with the ability to control and regulate such responses. Problems arise when one or other arm of the immune system develops inappropriately, resulting in inappropriate effector responses to harmless food proteins (allergy) or inadequate responses to pathogens (disease susceptibility).