Gómez M, Luque A, del Pozo M A, Hogg N, Sánchez-Madrid F, Cabañas C
Servicio de Immunología, Hospital de la Princesa-U.A.M., Madrid, Spain.
Eur J Immunol. 1997 Jan;27(1):8-16. doi: 10.1002/eji.1830270103.
The state of integrin activation can be assessed by monoclonal antibodies (mAb) that selectively recognize integrins in their active form. We demonstrate herein that the expression of the epitope recognized by mAb HUTS-21 is induced on T lymphoblasts upon binding of soluble vascular cell adhesion molecule (VCAM)-1 and an 80-kDa tryptic fragment of fibronectin (FN80) to the beta1 integrins very late activation antigen (VLA)-4 and VLA-5, and that this effect is dependent on ligand concentration and is specific for beta1 integrins. On T lymphoblasts adhering to immobilized fibronectin, the HUTS-21 epitope localized exclusively to sites of integrin binding to fibronectin. These results indicate that mAb HUTS-21 recognizes a ligand-induced binding site (LIBS) on the common beta1 subunit of VLA proteins. Engagement of beta1 integrins through this LIBS epitope inhibited T lymphoblast movement on fibronectin, as determined by quantitative time-lapse video microscopy studies. Furthermore, the HUTS-21 mAb also prevented T lymphoblast-directed migration through gradients of substratum-immobilized beta1 integrin ligands such as fibronectin or VCAM-1, whereas it did not affect migration on intercellular adhesion molecule (ICAM)-1. This anti-LIBS mAb stimulated cell adhesion through postreceptor events, without affecting receptor affinity for ligand, and appears to interfere with cell migration by a mechanism distinct from that of other anti-beta1 activating antibodies.
整联蛋白的激活状态可通过选择性识别处于活性形式的整联蛋白的单克隆抗体（mAb）来评估。我们在此证明，当可溶性血管细胞黏附分子（VCAM）-1和纤连蛋白的一个80 kDa胰蛋白酶片段（FN80）与β1整联蛋白极晚期活化抗原（VLA）-4和VLA-5结合时，mAb HUTS-21识别的表位在T淋巴母细胞上被诱导表达，且这种效应依赖于配体浓度，并且对β1整联蛋白具有特异性。在黏附于固定化纤连蛋白的T淋巴母细胞上，HUTS-21表位仅定位于整联蛋白与纤连蛋白结合的部位。这些结果表明，mAb HUTS-21识别VLA蛋白共同β1亚基上的一个配体诱导结合位点（LIBS）。通过定量延时视频显微镜研究确定，通过这个LIBS表位使β1整联蛋白结合可抑制T淋巴母细胞在纤连蛋白上的移动。此外，HUTS-21 mAb还可阻止T淋巴母细胞通过基质固定化的β1整联蛋白配体（如纤连蛋白或VCAM-1）梯度进行定向迁移，而它不影响在细胞间黏附分子（ICAM）-1上的迁移。这种抗LIBS mAb通过受体后事件刺激细胞黏附，而不影响受体对配体的亲和力，并且似乎通过一种不同于其他抗β1激活抗体的机制干扰细胞迁移。
