Jones L A, Izon D J, Nieland J D, Linsley P S, Kruisbeek A M
Division of Immunology, Netherlands Cancer Institute, Amsterdam.
Int Immunol. 1993 May;5(5):503-12. doi: 10.1093/intimm/5.5.503.
Activation of antigen specific T cells requires more than stimulation through the TCR-CD3 complex. A second or costimulatory signal is also required, and this second signal can be delivered by interactions between CD28 and B7, ligands expressed on T cells and antigen presenting cells respectively. We have examined the role of the CD28-B7 interaction in superantigen mediated T cell activation and intrathymic negative selection by blocking B7 molecules with a high affinity soluble ligand, CTLA4lg. In vitro T cell activation mediated by both virally encoded endogenous and exogenous bacterial superantigens was significantly blocked by the addition of CTL4Alg to cultures. However, intrathymic clonal deletion in vivo and in fetal thymic organ cultures was not inhibited by blocking B7 molecules. Therefore, although the CD28-B7 costimulation pathway is necessary for T cell activation, it does not appear to play a role in intrathymic clonal deletion.
抗原特异性T细胞的激活需要的不仅仅是通过TCR-CD3复合物的刺激。还需要第二个或共刺激信号，这个第二个信号可以通过CD28与B7之间的相互作用传递，CD28和B7分别是T细胞和抗原呈递细胞上表达的配体。我们通过用高亲和力可溶性配体CTLA4lg阻断B7分子，研究了CD28-B7相互作用在超抗原介导的T细胞激活和胸腺内阴性选择中的作用。向培养物中添加CTL4Alg可显著阻断由病毒编码的内源性和外源性细菌超抗原介导的体外T细胞激活。然而，体内和胎儿胸腺器官培养中的胸腺内克隆缺失并未因阻断B7分子而受到抑制。因此，尽管CD28-B7共刺激途径对于T细胞激活是必需的，但它似乎在胸腺内克隆缺失中不起作用。
