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具有超抗原特性的葡萄球菌和链球菌毒素可分为3种氨基酸序列同源组、所有细菌超抗原均具有与MHC Ⅱ类抗原结合的位点,但起抗原中与MHC Ⅱ类抗原受体结合相关的共同结构的特性尚不清楚。在普通抗原识别中,T细胞的共同受体CD4使T细胞抗原受体与MHC Ⅱ类分子的接触稳定,这种CD4的稳定作用在促进低亲和力的相互作用上是至关重要的。已证明葡萄球的超抗原系直接结合于T细胞受体β链,使T细胞抗原受体与MHC Ⅱ类分于交联而产生信号传导。另外,现又提出超抗原是借助于一些内源性配体间接地与T细胞受体结合。
Staphylococcus aureus and streptococcal toxins with superantigen characteristics can be divided into three amino acid sequence homology groups. All bacterial superantigens have a site of binding with MHC class II antigen, but they bind to MHC class II antigen receptor The nature of the associated common structure is not clear. In common antigen recognition, T cell co-receptor CD4 stabilizes contact of T-cell antigen receptors with MHC class II molecules, and the stabilizing effect of CD4 is crucial in promoting low-affinity interactions. It has been proved that the superantigen of the stratum granulosum binds directly to the beta chain of the T cell receptor, so that the T cell antigen receptor is cross-linked with the MHC class II to generate signal transduction. In addition, it is also proposed that the superantigen is indirectly bound to the T cell receptor by means of some endogenous ligand.