Hill C A, Wallace W E, Keane M J, Mike P S
National Institute of Occupational Safety and Health, Morgantown, West Virginia, USA.
Cell Biol Toxicol. 1995 Apr;11(2):119-28. doi: 10.1007/BF00767497.
The macrophage-like cell line, P388D1, was exposed to dipalmitoyl lecithin (DPL)-coated respirable quartz and kaolin, and the disappearance of the DPL was monitored for up to 9 days. The coating was removed rapidly at first (about 50% in the first 3 days) and then more slowly over the remaining 6 days, until about 30% remained on day 9. The rate of DPL digestion was independent of the type of dust and the amount of coated dust within the cell, indicating the existence of an extracellular phospholipase activity. This extracellular phospholipase activity was partially characterized. It was sensitive to temperatures above 56 degrees C, the presence of EDTA, the action of the proteases trypsin and proteinase K, and pH, being active at pH 7 but not at pH 5. This is consistent with reports in the literature of the existence of an extralysosomal phospholipase which is active at pH 7 and dependent on the presence of divalent metal ions. There was a dust-dependent difference in the extracellular rate of DPL digestion from quartz and kaolin. The coating was removed more slowly from the kaolin than it was from quartz. The removal of the DPL coating seen in the presence of cells was presumably due to both an intracellular and an extracellular phospholipase.
将巨噬细胞样细胞系P388D1暴露于二棕榈酰卵磷脂（DPL）包被的可吸入性石英和高岭土中，并监测DPL的消失情况，长达9天。起初，包被迅速去除（头3天约50%），然后在剩余6天中去除速度减慢，直至第9天约30%残留。DPL的消化速率与细胞内粉尘类型及包被粉尘量无关，表明存在细胞外磷脂酶活性。对这种细胞外磷脂酶活性进行了部分特性鉴定。它对56℃以上温度、EDTA的存在、蛋白酶胰蛋白酶和蛋白酶K的作用以及pH敏感，在pH 7时有活性而在pH 5时无活性。这与文献报道一致，即存在一种在pH 7有活性且依赖二价金属离子存在的溶酶体外磷脂酶。石英和高岭土的细胞外DPL消化速率存在粉尘依赖性差异。高岭土上包被的去除比石英上更慢。在细胞存在下观察到的DPL包被的去除可能是由于细胞内和细胞外磷脂酶共同作用的结果。
