Beekhuizen H, Blokland I, van Furth R
Department of Infectious Diseases, University Hospital, Leiden, The Netherlands.
J Immunol. 1993 Feb 1;150(3):950-9.
The myeloid differentiation protein CD14 that is expressed on the surface of mature monocytes contributes to the adherence of monocytes to cytokine-stimulated monolayers of human macrovascular endothelial cells (EC). It has also been observed that the initial adherence of monocytes to cultured cytokine-stimulated EC eventually results in an ICAM-1- and LFA-1 (CD11a/CD18)-dependent adherence, which coincides with stretching and lateral migration of the monocytes over the surface of EC. Recently, it was reported that CD14 mediates monocyte activation and can induce a change in the avidity of CD11a/CD18 for its ligand ICAM-1. The aim of the present study was to investigate whether activation of monocytes by CD14 elicits a CD11/CD18-dependent adhesion of monocytes to ICAM-1 on rIL-1 alpha-stimulated EC. Incubation of monocytes with murine anti-CD14 mAb alone did not mobilize intracellular calcium but the subsequent addition of F(ab')2 anti-mouse Ig, which caused cross-linking of CD14 on the surface of monocytes, induced a transient rise in cytosolic free calcium concentration and enhanced the percentage monocytes that adhered to monolayers of macrovascular venous EC stimulated with rIL-1 alpha for 24 h, but not to nonstimulated EC. The elevated adhesion was decreased with monocytes were preincubated with staurosporine, an inhibitor of intracellular protein kinase activity and was markedly inhibited by mAb against the common beta 2-subunit (CD18) of the CD11/CD18 molecules on monocytes and by mAb against ICAM-1 on 24-h rIL-1 alpha-stimulated venous EC. These studies provide evidence for the hypothesis that the binding of monocytes via CD14 to rIL-1 alpha-stimulated EC generates an intracellular response in monocytes and triggers an adhesion mechanism that allows CD11/CD18 molecules on monocytes to bind to ICAM-1 on EC.
在成熟单核细胞表面表达的髓样分化蛋白CD14有助于单核细胞黏附于细胞因子刺激的人大血管内皮细胞（EC）单层。还观察到，单核细胞对培养的细胞因子刺激的EC的初始黏附最终导致依赖细胞间黏附分子-1（ICAM-1）和淋巴细胞功能相关抗原-1（LFA-1，CD11a/CD18）的黏附，这与单核细胞在EC表面的伸展和横向迁移相吻合。最近，有报道称CD14介导单核细胞活化，并可诱导CD11a/CD18对其配体ICAM-1的亲和力发生变化。本研究的目的是探讨CD14激活单核细胞是否会引发单核细胞对rIL-1α刺激的EC上ICAM-1的CD11/CD18依赖性黏附。单独用鼠抗CD14单克隆抗体孵育单核细胞不会动员细胞内钙，但随后添加F(ab')2抗小鼠Ig，其导致单核细胞表面CD14交联，诱导胞质游离钙浓度短暂升高，并增加了黏附于rIL-1α刺激24小时的大血管静脉EC单层的单核细胞百分比，但不增加黏附于未刺激EC的单核细胞百分比。用细胞内蛋白激酶活性抑制剂星形孢菌素预孵育单核细胞可降低升高的黏附，并且用针对单核细胞上CD11/CD18分子的共同β2亚基（CD18）的单克隆抗体以及针对24小时rIL-1α刺激的静脉EC上ICAM-1的单克隆抗体可显著抑制黏附。这些研究为以下假说提供了证据：单核细胞通过CD14与rIL-1α刺激的EC结合在单核细胞中产生细胞内反应，并触发一种黏附机制，使单核细胞上的CD11/CD18分子能够与EC上的ICAM-1结合。
