Campanero M R, del Pozo M A, Arroyo A G, Sánchez-Mateos P, Hernández-Caselles T, Craig A, Pulido R, Sánchez-Madrid F
Servicio de Inmunologìa, Hospital de la Princesa, Madrid, Spain.
J Cell Biol. 1993 Nov;123(4):1007-16. doi: 10.1083/jcb.123.4.1007.
The interaction of lymphocyte function-associated antigen-1 (LFA-1) with its ligands mediates multiple cell adhesion processes of capital importance during immune responses. We have obtained three anti-ICAM-3 mAbs which recognize two different epitopes (A and B) on the intercellular adhesion molecule-3 (ICAM-3) as demonstrated by sequential immunoprecipitation and cross-competitive mAb-binding experiments. Immunoaffinity purified ICAM-3-coated surfaces were able to support T lymphoblast attachment upon cell stimulation with both phorbol esters and cross-linked CD3, as well as by mAb engagement of the LFA-1 molecule with the activating anti-LFA-1 NKI-L16 mAb. T cell adhesion to purified ICAM-3 was completely inhibited by cell pretreatment with mAbs to the LFA-1 alpha (CD11a) or the LFA-beta (CD18) integrin chains. Anti-ICAM-3 mAbs specific for epitope A, but not those specific for epitope B, were able to trigger T lymphoblast homotypic aggregation. ICAM-3-mediated cell aggregation was dependent on the LFA-1/ICAM-1 pathway as demonstrated by blocking experiments with mAbs specific for the LFA-1 and ICAM-1 molecules. Furthermore, immunofluorescence studies on ICAM-3-induced cell aggregates revealed that both LFA-1 and ICAM-1 were mainly located at intercellular boundaries. ICAM-3 was located at cellular uropods, which in small aggregates appeared to be implicated in cell-cell contacts, whereas in large aggregates it appeared to be excluded from cell-cell contact areas. Experiments of T cell adhesion to a chimeric ICAM-1-Fc molecule revealed that the proaggregatory anti-ICAM-3 HP2/19 mAb was able to increase T lymphoblast attachment to ICAM-1, suggesting that T cell aggregation induced by this mAb could be mediated by increasing the avidity of LFA-1 for ICAM-1. Moreover, the HP2/19 mAb was costimulatory with anti-CD3 mAb for T lymphocyte proliferation, indicating that enhancement of T cell activation could be involved in ICAM-3-mediated adhesive phenomena. Altogether, our results indicate that ICAM-3 has a regulatory role on the LFA-1/ICAM-1 pathway of intercellular adhesion.
淋巴细胞功能相关抗原-1（LFA-1）与其配体的相互作用介导了免疫反应过程中多个至关重要的细胞黏附过程。我们获得了三种抗ICAM-3单克隆抗体，通过连续免疫沉淀和交叉竞争单克隆抗体结合实验证明，它们识别细胞间黏附分子-3（ICAM-3）上的两个不同表位（A和B）。免疫亲和纯化的ICAM-3包被表面在用佛波酯和交联的CD3刺激细胞时，以及通过用活化的抗LFA-1 NKI-L16单克隆抗体使LFA-1分子结合单克隆抗体时，能够支持T淋巴母细胞附着。用针对LFA-1α（CD11a）或LFA-β（CD18）整合素链的单克隆抗体对细胞进行预处理，可完全抑制T细胞与纯化的ICAM-3的黏附。针对表位A的抗ICAM-3单克隆抗体能够触发T淋巴母细胞同型聚集，而针对表位B的单克隆抗体则不能。如用针对LFA-1和ICAM-1分子的单克隆抗体进行阻断实验所示，ICAM-3介导的细胞聚集依赖于LFA-1/ICAM-1途径。此外，对ICAM-3诱导的细胞聚集体进行的免疫荧光研究表明，LFA-1和ICAM-1主要位于细胞间边界。ICAM-3位于细胞尾足，在小聚集体中似乎参与细胞间接触，而在大聚集体中似乎被排除在细胞间接触区域之外。T细胞与嵌合ICAM-1-Fc分子黏附的实验表明，具有促聚集作用的抗ICAM-3 HP2/19单克隆抗体能够增加T淋巴母细胞与ICAM-1的附着，这表明该单克隆抗体诱导的T细胞聚集可能是通过增加LFA-1对ICAM-1的亲和力来介导的。此外，HP2/19单克隆抗体与抗CD3单克隆抗体共同刺激T淋巴细胞增殖，表明T细胞活化的增强可能参与ICAM-3介导的黏附现象。总之，我们的结果表明ICAM-3在细胞间黏附的LFA-1/ICAM-1途径中具有调节作用。
