Masinovsky B, Urdal D, Gallatin W M
Fred Hutchinson Cancer Research Center, Seattle, WA 98104.
J Immunol. 1990 Nov 1;145(9):2886-95.
Adhesion of lymphocytes to endothelial cells (EC) is the requisite first element in the multistep process of transmigration from blood across the postcapillary venules. Selective expression of cell adhesion molecules (CM) by microvascular EC in lymphoid organs (e.g., lymph nodes) and during tissue inflammation modulates this traffic in a site-directed manner. CAM synthesis by EC is regulated in turn by cytokines released in the local microenvironment. Studies done largely with human umbilical vein EC have implicated IL-1, IFN-gamma, and TNF-alpha as cytokines which promote leukocyte adhesion to EC. In the work reported here, the responses of cultured microvascular EC derived from macaque lymph nodes to IL-1beta, IL-2, IFN-gamma, and IL-4 were examined. Increases in lymphocyte adhesion after preculture of microvascular EC in IL-1beta or IFN-gamma were typically 2-to 4-fold above controls and comparable to those reported for human umbilical vein EC. IL-2 had no effect. In contrast, IL-4 markedly enhanced adhesion to microvascular EC. IL-4-induced adhesion was observed as early as 4 h after induction, plateaued by 24 h, was stable through 72 h of culture, but decayed to basal levels within 72 h after removal of IL-4 from the cultures. IL-1beta, but not IL-2 or IFN-gamma, synergistically enhanced the action of IL-4 on cultured microvascular EC to promote lymphocyte binding. Adhesion triggered in this manner required de novo protein synthesis. However, the avidity of IL-4-activated microvascular EC for lymphocytes, and analyses of kinetics, cation and temperature dependence, and/or lack of blockade with mAb to endothelial leukocyte adhesion molecule-1, intra-cellular adhesion molecule-1, and MECA-79 indicated that these CAM were not central to the phenomenon. To aid identification of the relevant CAM, mAb specific to IL-4-induced microvascular EC were produced. One of these, 6G10, blocked up to 90% of lymphocyte adhesion to IL-4-induced microvascular EC, immunoprecipitated an IL-4-induced cell-surface molecule of 110-kDa molecular mass, and reacted specifically with Chinese hamster ovary cells transfected with human vascular cell adhesion molecule-1. Our results suggest that IL-4 may have potent effects on lymphocyte recirculation in vivo.
淋巴细胞与内皮细胞（EC）的黏附是从血液穿过毛细血管后微静脉进行跨膜迁移的多步骤过程中必不可少的首要环节。微血管内皮细胞在淋巴器官（如淋巴结）以及组织炎症期间对细胞黏附分子（CM）的选择性表达，以位点定向的方式调节这种细胞运输。内皮细胞合成细胞黏附分子又受到局部微环境中释放的细胞因子的调控。此前主要针对人脐静脉内皮细胞开展的研究表明，白细胞介素-1（IL-1）、γ干扰素（IFN-γ）和肿瘤坏死因子-α（TNF-α）是促进白细胞与内皮细胞黏附的细胞因子。在本文报道的研究中，检测了源自猕猴淋巴结的培养微血管内皮细胞对IL-1β、IL-2、IFN-γ和IL-4的反应。微血管内皮细胞在IL-1β或IFN-γ中预培养后，淋巴细胞黏附增加，通常比对照高2至4倍，与人脐静脉内皮细胞的报道相当。IL-2没有作用。相反，IL-4显著增强了对微血管内皮细胞的黏附。IL-4诱导的黏附最早在诱导后4小时观察到，24小时达到平台期，在72小时的培养过程中保持稳定，但在从培养物中去除IL-4后72小时内降至基础水平。IL-1β而非IL-2或IFN-γ协同增强了IL-4对培养微血管内皮细胞促进淋巴细胞结合的作用。以这种方式引发的黏附需要从头合成蛋白质。然而，IL-4激活的微血管内皮细胞对淋巴细胞的亲和力，以及对动力学、阳离子和温度依赖性的分析，和/或用针对内皮细胞白细胞黏附分子-1、细胞内黏附分子-1和MECA-79的单克隆抗体进行阻断的实验表明，这些细胞黏附分子并非该现象的核心因素。为了有助于鉴定相关的细胞黏附分子，制备了针对IL-4诱导的微血管内皮细胞的特异性单克隆抗体。其中一种单克隆抗体6G10可阻断高达90%的淋巴细胞与IL-4诱导的微血管内皮细胞的黏附，免疫沉淀出一种分子量为110 kDa的IL-4诱导的细胞表面分子，并与转染了人血管细胞黏附分子-1的中国仓鼠卵巢细胞特异性反应。我们的结果表明，IL-4可能在体内对淋巴细胞再循环有强大作用。
