Division of Drug Research, Department of Medical and Health Sciences, Linköping University, 581 85 Linköping, Sweden.
Inflamm Res. 2010 Feb;59(2):89-95. doi: 10.1007/s00011-009-0071-1. Epub 2009 Aug 11.
We have recently shown that terminal sialic acid residues are essential for alpha(1)-acid glycoprotein (AGP)-induced Ca(2+) mobilization in neutrophils. The aim of the present study was to establish the importance of sialic acid residues on AGP in modulating human neutrophil functions, with emphasis on the generation of reactive oxygen species (ROS).
ROS were measured by luminol-enhanced chemiluminescence in isolated human neutrophils.
We found that AGP did not provoke ROS generation in resting or L-selectin presensitized neutrophils. Moreover, AGP did not affect the N-formyl-methionyl-leucyl-phenylalanine (fMLP)-induced ROS generation, but it slightly suppressed opsonized zymosan-induced responses. However, when the neutrophils were prestimulated with fMLP, the subsequent addition of AGP provoked a marked ROS response. Dose-response studies and time studies revealed that the ROS generating capacity of AGP was highest at a concentration of 0.05 mg/ml and when given 3-10 min after addition of fMLP. A desialylated form of AGP or pretreatment of neutrophils with 3'- and 6'-sialyllactose caused a substantially lower ROS response in neutrophils prestimulated with fMLP.
Our data show that AGP can stimulate a second ROS response in fMLP preactivated neutrophils and that terminal sialic acid residues on AGP play a crucial role in this regard.
我们最近发现，末端唾液酸残基对于α(1)-酸性糖蛋白（AGP）诱导中性粒细胞内钙离子动员是必需的。本研究的目的是确定 AGP 上唾液酸残基在调节人中性粒细胞功能中的重要性，重点是活性氧（ROS）的生成。
通过分离的人中性粒细胞中的发光增强化学发光法测量 ROS。
我们发现，AGP 不会引起静息或 L-选择素预敏化中性粒细胞中的 ROS 生成。此外，AGP 不会影响 N-甲酰基-甲硫氨酸-亮氨酸-苯丙氨酸（fMLP）诱导的 ROS 生成，但它轻微抑制调理的酵母聚糖诱导的反应。然而，当中性粒细胞用 fMLP 预刺激时，随后添加 AGP 会引发明显的 ROS 反应。剂量反应研究和时间研究表明，AGP 的 ROS 生成能力在 0.05mg/ml 的浓度下最高，并且在添加 fMLP 后 3-10 分钟给予时最高。脱唾液酸化的 AGP 形式或用 3′-和 6′-唾液乳糖预处理中性粒细胞会导致用 fMLP 预刺激的中性粒细胞中的 ROS 反应大大降低。
我们的数据表明，AGP 可以刺激 fMLP 预激活中性粒细胞中的第二个 ROS 反应，并且 AGP 上的末端唾液酸残基在这方面起着至关重要的作用。
