Montufar-Solis Dina, Garza Tomas, Klein John R
Department of Diagnostic Sciences, Dental Branch, University of Texas Health Science Center at Houston, Houston, TX, USA.
Immunol Rev. 2007 Feb;215:189-201. doi: 10.1111/j.1600-065X.2006.00471.x.
The vast majority of peripheral T cells exist as resting lymphocytes until a signal for activation has been received. In response to antigen, this activation involves ligation of the T-cell receptor (TCR) and signal transmission through the CD3 complex, which then initiates a cascade of intracellular events that lead to the expression of genes used in T-cell activation. T-cell activation also requires soluble mediators in the form of cytokines and chemokines that regulate the process in both positive and negative ways, and costimulatory signals received in conjunction with TCR/CD3 signaling are important in the activation of T cells. Unlike T cells in other peripheral immune compartments, small and large intestinal intraepithelial lymphocytes (IELs) bear some but not all properties of activated T cells, suggesting that they constitute a large population of 'partially activated' effector cells. Thus, regulation of the IEL activation process must be held in tight check, yet it must be ready to respond to foreign antigen rapidly and effectively. We discuss how costimulatory molecules may hold the key to controlling IEL activation through a multiphase process beginning with cells that have already entered into the early stage of activation.
绝大多数外周T细胞以静息淋巴细胞的形式存在，直到接收到激活信号。响应抗原时，这种激活涉及T细胞受体（TCR）的连接以及通过CD3复合物的信号传递，进而启动一系列细胞内事件，导致T细胞激活相关基因的表达。T细胞激活还需要细胞因子和趋化因子形式的可溶性介质，它们以正负两种方式调节该过程，并且与TCR/CD3信号传导一起接收的共刺激信号在T细胞激活中很重要。与其他外周免疫区室中的T细胞不同，小肠和大肠上皮内淋巴细胞（IEL）具有一些但并非全部激活T细胞的特性，这表明它们构成了大量“部分激活”的效应细胞群体。因此，IEL激活过程的调节必须严格控制，但它必须准备好快速有效地对外来抗原作出反应。我们讨论了共刺激分子如何通过一个多阶段过程来控制IEL激活，这个过程从已经进入激活早期阶段的细胞开始。
