Wyer J R, Willcox B E, Gao G F, Gerth U C, Davis S J, Bell J I, van der Merwe P A, Jakobsen B K
Nuffield Department of Clinical Medicine, Institute of Molecular Medicine, John Radcliffe Hospital, Oxford, United Kingdom.
Immunity. 1999 Feb;10(2):219-25. doi: 10.1016/s1074-7613(00)80022-9.
The T cell surface glycoprotein CD8 enhances T cell antigen recognition by binding to MHC class I molecules. We show that human CD8 alphaalpha binds to the MHC class I molecule HLA-A2 with an extremely low affinity (Kd approximately 0.2 mM at 37 degrees C) and with kinetics that are between 2 and 3 orders of magnitude faster than reported for T cell receptor/peptide-MHC interactions. Furthermore, CD8 alphaalpha had no detectable effect on a T cell receptor (TCR) binding to the same peptide-MHC class I complex. These binding properties provide an explanation as to why the CD8/MHC class I interaction is unable to initiate cell-cell adhesion and how it can enhance TCR recognition without interfering with its specificity.
T细胞表面糖蛋白CD8通过与MHC I类分子结合来增强T细胞对抗原的识别。我们发现，人CD8αα以极低的亲和力（37℃时Kd约为0.2 mM）与MHC I类分子HLA - A2结合，其动力学比报道的T细胞受体/肽 - MHC相互作用快2至3个数量级。此外，CD8αα对T细胞受体（TCR）与同一肽 - MHC I类复合物的结合没有可检测到的影响。这些结合特性解释了为什么CD8/MHC I类相互作用无法启动细胞间粘附，以及它如何在不干扰其特异性的情况下增强TCR识别。
