Mondino A, Khoruts A, Jenkins M K
Department of Microbiology and the Center for Immunology, University of Minnesota Medical School, Minneapolis 55455, USA.
Proc Natl Acad Sci U S A. 1996 Mar 19;93(6):2245-52. doi: 10.1073/pnas.93.6.2245.
The mammalian immune system must specifically recognize and eliminate foreign invaders but refrain from damaging the host. This task is accomplished in part by the production of a large number of T lymphocytes, each bearing a different antigen receptor to match the enormous variety of antigens present in the microbial world. However, because antigen receptor diversity is generated by a random mechanism, the immune system must tolerate the function of T lymphocytes that by chance express a self-reactive antigen receptor. Therefore, during early development, T cells that are specific for antigens expressed in the thymus are physically deleted. The population of T cells that leaves the thymus and seeds the secondary lymphoid organs contains helpful cells that are specific for antigens from microbes but also potentially dangerous T cells that are specific for innocuous extrathymic self antigens. The outcome of an encounter by a peripheral T cell with these two types of antigens is to a great extent determined by the inability of naive T cells to enter nonlymphoid tissues or to be productively activated in the absence of inflammation.
哺乳动物的免疫系统必须特异性地识别并清除外来入侵者，同时避免损伤宿主。这项任务部分是通过产生大量的T淋巴细胞来完成的，每个T淋巴细胞都带有不同的抗原受体，以匹配微生物世界中存在的种类繁多的抗原。然而，由于抗原受体的多样性是通过随机机制产生的，免疫系统必须容忍偶然表达自身反应性抗原受体的T淋巴细胞的功能。因此，在早期发育过程中，对胸腺中表达的抗原具有特异性的T细胞会被物理性清除。离开胸腺并定植于次级淋巴器官的T细胞群体中，既包含对微生物抗原具有特异性的有益细胞，也包含对无害的胸腺外自身抗原具有特异性的潜在危险T细胞。外周T细胞与这两种抗原相遇的结果在很大程度上取决于初始T细胞在没有炎症的情况下无法进入非淋巴组织或被有效激活。
