Selectins and integrins are key players in the adhesion and signaling cascade that recruits leukocytes to inflamed tissues. Selectin binding induces β2 integrin binding to slow leukocyte rolling. Here, a micropipette was used to characterize neutrophil adhesion to E-selectin and intercellular adhesion molecule-1 (ICAM-1) at room temperature. The time-dependent adhesion frequency displayed two-stage kinetics, with an E-selectin-mediated fast increase to a low plateau followed by a slow increase to a high plateau mediated by intermediate-affinity binding of integrin αLβ2 to ICAM-1. The αLβ2 activation required more than 5 s contact to E-selectin and spleen tyrosine kinase (Syk) activity. A multi-zone channel was used to analyze αLβ2 activation by P-selectin in separate zones of receptors or antibodies, finding an inverse relationship between the rolling velocity on ICAM-1 and P-selectin dose, and a P-selectin dose-dependent change from bent to extended conformations with a closed headpiece that was faster at 37°C than at room temperature. Activation of αLβ2 exhibited different levels of cooperativity and persistent times depending on the strength and duration of selectin stimulation. These results define the precise timing and kinetics of intermediate activation of αLβ2 by E- and P-selectins.

中文翻译：

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E-选择素和 P-选择素诱导的中性粒细胞上整合素 αLβ2 的中间活化的动力学。

选择素和整合素是粘附和信号级联的关键参与者，将白细胞募集到发炎的组织。选择素结合诱导 β2 整合素结合以减缓白细胞滚动。在这里，微量移液器用于表征中性粒细胞在室温下与 E-选择素和细胞间粘附分子-1 (ICAM-1) 的粘附。时间依赖性粘附频率显示出两阶段动力学，E-选择素介导的快速增加至低平台，然后缓慢增加至由整合素αLβ2与ICAM-1的中等亲和力结合介导的平台。αLβ2 激活需要 5 秒以上才能与 E-选择素和脾酪氨酸激酶 (Syk) 活性接触。多区域通道用于分析 P-选择素在受体或抗体的不同区域中对 αLβ2 的激活，发现 ICAM-1 的滚动速度和 P-选择素剂量之间存在反比关系，以及 P-选择素剂量依赖性变化，从弯曲构象到扩展构象，封闭式头件在 37°C 下比在室温下更快。取决于选择素刺激的强度和持续时间，αLβ2 的激活表现出不同水平的协同性和持续时间。这些结果定义了 E-和 P-选择素对 αLβ2 的中间激活的精确时间和动力学。