β2整合素介导的人中性粒细胞在ICAM-1裱衬表面的铺展动力学

Spreading dynamics of β2 integrin-expressed human neutrophils onto ICAM-1-immobilized substrate

目的研究由表达于人中性粒细胞表面的β2整合素与胞间黏附分子-1(intercellular adhesion molecule-1,ICAM-1)裱衬表面相互作用介导人中性粒细胞铺展的动力学过程。方法以裱衬2%人血清白蛋白(human serumalbumin,HSA)和空白的底板为对照,分别考察裱衬了10、20和100μg/mL ICAM-1的底板上人中性粒细胞铺展比例随时间的变化规律。通过流式细胞仪检测人中性粒细胞β2整合素的表达量,以及采用抗体阻断β2整合素的CD11a或CD11b亚基,观察其在100μg/mL ICAM-1裱衬表面细胞铺展比例随时间的改变情况。结果中性粒细胞在裱衬2%HSA的表面不铺展,在裱衬ICAM-1表面的铺展动力学依赖于ICAM-1浓度,并与β2整合素表达量相关;抗CD11b抗体阻断后,中性粒细胞在裱衬ICAM-1表面的铺展明显减少。结论人中性粒细胞在ICAM-1表面的铺展是由β2整合素与其配体ICAM-1特异性相互作用介导的,并且CD11b亚基对铺展过程起主要调控作用。

Objective To elucidate the spreading dynamics of β2 integrin-expressed human neutrophils（PMNs） on ICAM-1-immobilized substrate.Methods The fraction of PMN spreading on the substrate pre-coated by 10,20,or 100 μg/mL intercellular adhesive molecule-1（ICAM-1） was quantified when that on 2% human serum albumin（HSA）-immobilized or that on blank substrate was served as control.The site density of β2 integrin expressing on PMNs was determined using flow cytometry and the regulation of β2 integrin subunits was defined using the fraction of PMN spreading on 100 μg/mL ICAM-1 substrate by blocking CD11a or CD11b subunit of β2 integrin.Results PMN spreading was presented on ICAM-1-immobilized substrate but absent on 2% HSA-immobilized substrate,supporting the specificity of β2 integrin-induced spreading.Time course of neutrophil spreading on ICAM-1 substrate was density-dependent of both ICAM-1 and β2 integrin molecules.The fraction of PMN spreading was reduced significantly when the expression of CD11b subunit was blocked.Conclusions PMN spreading was mediated specifically by β2 integrin-ICAM-1 interactions and determined by the expression of β2 integrin and ICAM-1,in which CD11b subunit played a dominate role.