A major role for phospholipase A2 in antigen-induced arachidonic acid release in rat mast cells.
A major role for phospholipase A2 in antigen-induced arachidonic acid release in rat mast cells.
复制标题
磷脂酶 A2 在大鼠肥大细胞中抗原诱导的花生四烯酸释放中起主要作用。
作者：
K. Yamada;Y. Okano;K. Miura;Y. Nozawa
抗原刺激使IgE受体交联，导致大鼠腹腔肥大细胞释放组胺和花生四烯酸。研究人员报告称，[³H]花生四烯酸的分布因标记条件而异。将来自大鼠腹腔的肥大细胞在30℃或37℃下用[³H]花生四烯酸标记不同时间。通过细胞活力（台盼蓝摄取）、反应性（组胺释放）和放射性分布判断，发现在30℃下用[³H]花生四烯酸孵育4小时标记效果最佳。在抗原（2,4 - 二硝基苯基偶联的猪蛔虫提取物）刺激下，检测了标记至平衡的肥大细胞中³H放射性分布的变化。结果表明，[³H]花生四烯酸主要从磷脂酰胆碱中丢失，在较小程度上从磷脂酰肌醇中丢失。放射性标记的磷脂酸和二酰基甘油的短暂出现表明磷脂酶C水解了磷脂酰肌醇。用磷脂酶A₂抑制剂米帕林预处理，可显著阻止抗原诱导的[³H]花生四烯酸从磷脂酰胆碱中释放。因此可以得出结论，在抗原刺激的肥大细胞释放花生四烯酸的过程中，水解磷脂酰胆碱的磷脂酶A₂途径是主要途径，磷脂酶C/二酰基甘油脂肪酶途径仅起次要作用。
Cross-linking of IgE receptors by antigen stimulation leads to histamine release and arachidonic acid release in rat peritoneal mast cells. Investigators have reported a diverse distribution of [3H]arachidonate that is dependent on labelling conditions. Mast cells from rat peritoneal cavity were labelled with [3H]arachidonic acid for different periods of time at either 30 or 37 degrees C. Optimum labelling was found to be after 4 h incubation with [3H]arachidonate at 30 degrees C, as judged by cell viability (Trypan Blue uptake), responsiveness (histamine release) and distribution of radioactivity. Alterations in 3H-radioactivity distribution in mast cells labelled to equilibrium were examined on stimulation with antigen (2,4-dinitrophenyl-conjugated Ascaris suum extract). The results indicated that [3H]arachidonic acid was lost mainly from phosphatidylcholine and, to a lesser extent, from phosphatidylinositol. A transient appearance of radiolabelled phosphatidic acid and diacylglycerol indicated phosphatidylinositol hydrolysis by phospholipase C. Pretreatment with a phospholipase A2 inhibitor, mepacrine, substantially prevented the antigen-induced liberation of [3H]arachidonic acid from phosphatidylcholine. It can be thus concluded that, in the release of arachidonic acid by antigen-stimulated mast cells, the phospholipase A2 pathway, in which phosphatidylcholine is hydrolysed, serves as the major one, the phospholipase C/diacylglycerol lipase pathway playing only a minor role.