Hentzen E R, Neelamegham S, Kansas G S, Benanti J A, McIntire L V, Smith C W, Simon S I
Speros Martel Section of Leukocyte Biology, Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA.
Blood. 2000 Feb 1;95(3):911-20.
The relative contributions of CD11a/CD18 and CD11b/CD18 to the dynamics and strength of neutrophil adhesion to intercellular adhesion molecule (ICAM)-1-transfected cells were examined over the time course of chemotactic stimulation. Suspensions of neutrophils and transfectants were sheared in a cone-plate viscometer, and formation of heterotypic aggregates was measured by 2-color flow cytometry. The 2-body collision theory was used to compute adhesion efficiency, defined as the proportion of collisions between neutrophils and target cells that resulted in capture. ICAM-1 surface density and shear rate both regulated adhesion efficiency. Target cells expressing approximately 1000 ICAM-1 sites/microm(2) (I(low)) were captured with an efficiency of 0.15 at 100 s(-1), which decreased to zero at 300 s(-1). At 8-fold higher ICAM-1 expression (I(high)) corresponding to levels measured on interleukin-1-stimulated endothelium, efficiency was 0.3 at 100 s(-1) and remained above background to 900 s(-1). Shear alone was sufficient for CD11a/CD18-mediated adhesion to ICAM-1, and stimulation with formyl-methionyl-leucyl-phenylalanine boosted capture efficiency through CD11a/CD18 by 4-fold. In comparison, CD11b/CD18 supported one third of this efficiency, but was necessary for aggregate stability over several minutes of shear and at shear stresses exceeding 5 dyne/cm(2). Hydrodynamics influenced capture efficiency predominantly through the collisional contact duration, predicted to be approximately 9 milliseconds for successful capture of I(low) and 4 milliseconds for I(high). The implication is that an increase in ICAM-1 from resting levels to those on inflamed endothelium effectively increases the permissible shear in which capture through beta(2)-integrins may occur. Neutrophil adhesion to ICAM-1 appears to be a cooperative and sequential process of CD11a-dependent capture followed by CD11b-mediated stabilization.
在趋化刺激的时间进程中，研究了CD11a/CD18和CD11b/CD18对中性粒细胞与细胞间黏附分子（ICAM）-1转染细胞黏附的动力学和强度的相对贡献。将中性粒细胞和转染细胞的悬浮液在锥板粘度计中剪切，通过双色流式细胞术测量异型聚集体的形成。采用双体碰撞理论计算黏附效率，黏附效率定义为中性粒细胞与靶细胞之间导致捕获的碰撞比例。ICAM-1表面密度和剪切速率均调节黏附效率。表达约1000个ICAM-1位点/微米²（I低）的靶细胞在100秒⁻¹时的捕获效率为0.15，在300秒⁻¹时降至零。在白细胞介素-1刺激的内皮细胞上测得的ICAM-1表达水平高8倍（I高）时，在100秒⁻¹时效率为0.3，在900秒⁻¹时仍高于背景水平。单独的剪切力足以实现CD11a/CD18介导的与ICAM-1的黏附，用甲酰甲硫氨酰亮氨酰苯丙氨酸刺激可使通过CD11a/CD18的捕获效率提高4倍。相比之下，CD11b/CD18支持该效率的三分之一，但对于在几分钟的剪切过程中以及在超过5达因/厘米²的剪切应力下聚集体的稳定性是必需的。流体动力学主要通过碰撞接触持续时间影响捕获效率，成功捕获I低时预计约为9毫秒，捕获I高时预计约为4毫秒。这意味着ICAM-1从静止水平增加到炎症内皮细胞上的水平有效地增加了通过β₂整合素发生捕获的允许剪切力。中性粒细胞与ICAM-1的黏附似乎是一个协同且有序的过程，先是依赖CD11a的捕获，随后是CD11b介导的稳定。
