Tominaga Y, Kita Y, Satoh A, Asai S, Kato K, Ishikawa K, Horiuchi T, Takashi T
New Product Research Laboratories III, Daiichi Pharmaceutical Co., Tokyo, Japan.
J Immunol. 1998 Oct 15;161(8):4016-22.
LFA-1 is a member of the beta2 integrin family, and interacts with ICAM-1, a member of the Ig superfamily containing five Ig-like domains. Interaction of LFA-1 with ICAM-1 is important in a number of cellular events, including Ag-specific T cell activation and leukocyte transendothelial migration, which are known to be typically transient and highly regulated. In this study, we have used surface plasmon resonance technology to study the ICAM-1/LFA-1 interaction at the molecular level. A soluble form of LFA-1 (sLFA-1), normally expressed as two noncovalently associated membrane-bound subunits, has been produced, and its interaction with ICAM-1 has been examined. The kinetic analysis of a monomeric sLFA-1 binding to the first two domains of ICAM-1 expressed as a chimeric IgG fusion protein (D1D2-IgG) revealed that sLFA-1 was bound to the D1D2-IgG chimera with a Kd of 500 nM and dissociated with a k(diss) of 0.1 s(-1). Monomeric membrane-bound LFA-1 purified from plasma membranes showed a similar kinetic to sLFA-1. These results suggest that the monovalent interaction between ICAM-1 and LFA-1 has a primarily high affinity and a slow dissociation rate constant as compared with other adhesion molecules, suggesting a potential mechanism for firm adhesion.
淋巴细胞功能相关抗原-1（LFA-1）是β2整合素家族的成员，可与细胞间黏附分子-1（ICAM-1）相互作用，ICAM-1是免疫球蛋白（Ig）超家族的成员，含有五个Ig样结构域。LFA-1与ICAM-1的相互作用在许多细胞事件中很重要，包括抗原特异性T细胞活化和白细胞跨内皮迁移，这些过程通常是短暂的且受到高度调控。在本研究中，我们使用表面等离子体共振技术在分子水平上研究ICAM-1/LFA-1的相互作用。已经制备了通常以两个非共价结合的膜结合亚基形式表达的可溶性LFA-1（sLFA-1），并检测了其与ICAM-1的相互作用。对与作为嵌合IgG融合蛋白（D1D2-IgG）表达的ICAM-1的前两个结构域结合的单体sLFA-1的动力学分析表明，sLFA-1以500 nM的解离常数（Kd）与D1D2-IgG嵌合体结合，并以0.1 s(-1)的解离速率常数（k(diss)）解离。从质膜纯化的单体膜结合LFA-1显示出与sLFA-1相似的动力学。这些结果表明，与其他黏附分子相比，ICAM-1和LFA-1之间的单价相互作用具有主要的高亲和力和缓慢的解离速率常数，这表明了一种牢固黏附的潜在机制。
