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T细胞活化不仅需要抗原特异性T细胞受体 (TCR)与抗原递呈细胞 (APC)上的抗原肽 MHC分子复合物的相互作用 ,同时还需要协同刺激信号。如果只有TCR介导的抗原特异性信号 ,而没有协同刺激信号 ,T细胞不但不能有效活化 ,而且会处于无能 (anergy)状态。协同刺激信号是通过T细胞上的协同刺激受体与相应配体相互作用而介导的。这些协同刺激配体和受体在结构上非常相似 ,同属于免疫球蛋白超家族 ,分别组成B7和CD2 8分子家族。其中经典的B7 1/B7 2—CD2 8/CTLA 4协同刺激途径对细胞的活化和耐受起关键性调节作用。而近年来新发现的协同刺激途径则对已经活化的效应性T细胞具有重要的调节作用。这些新的B7样协同刺激分子 ,除表达于专职APC (professionalAPC)上外 ,大多数还诱导性表达于非淋巴组织细胞上 ,可能对外周组织中的T细胞反应具有调节作用。对协同刺激分子的深入研究 ,可以加深对免疫相关性疾病发生、发展机制的认识 ,从而为临床提供新的免疫治疗途径。
T cell activation requires not only the interaction of the antigen-specific T cell receptor (TCR) with the antigen peptide MHC molecule complex on antigen presenting cells (APCs), but also synergistic stimulation signals. If only TCR-mediated antigen-specific signal, and no costimulatory signal, T cells not only can not be effectively activated, and will be in anergy (anergy) state. Costimulatory signals are mediated through the interaction of costimulatory receptors on T cells with the corresponding ligands. These costimulatory ligands and receptors are structurally very similar and belong to the immunoglobulin superfamily, forming the B7 and CD2 8 family of molecules, respectively. Among them, the classical B7 1 / B7 2 -CD2 8 / CTLA 4 costimulatory pathway plays a key regulatory role on cell activation and tolerance. In recent years, the newly discovered costimulatory pathway has an important regulatory effect on activated effector T cells. In addition to being expressed on the professional APC, most of these novel B7-like costimulatory molecules are also inducibly expressed on non-lymphoid cells and may have a regulatory effect on T cell responses in peripheral tissues. In-depth research on costimulatory molecules can deepen the understanding of the pathogenesis and development of immune-related diseases and provide a new immunotherapy approach for clinical practice.