Griese M, Beck J
Kinderpoliklinik, Ludwig-Maximilians-University, Pettenkoferstr 8a, Munich, D-80336, Germany.
Eur J Med Res. 1997 Apr 21;2(4):144-8.
To better understand the interaction of phosphatidylcholine liposomes with lung type II cells, their association with rat type II pneumocytes in primary culture was investigated. With a filtration assay technique free and cellularly bound liposomes were separated and an apparent binding site with a Bmax of 171 nmol/mg protein and a Kd of 470 nmol/l was detected. Bound liposomes were displacable by an excess of unlabelled liposomes, were sensitive to EDTA and trypsin treatment and were not significantly competed with by dioleyl-phosphatidylcholine liposomes. However, a site with identical characteristics was demonstrated in experiments performed with blanc dishes in the absence of cells. This site was generated by liposomes bound to the blanc culture dish, which could not be removed by extensive washing, but which were released by EDTA and trypsin and were trapped during filtration. These problems were overcome by a centrifugation assay technique. Then non-specific binding was less than 1% and cellular binding was inhibited dose-dependently by liposomes made from various phospholipids. These studies may facilitate attempts to direct liposomes as carriers to specific cellular targets in the lungs.
为了更好地理解磷脂酰胆碱脂质体与肺II型细胞的相互作用，研究了其与原代培养的大鼠II型肺细胞的结合情况。采用过滤分析技术分离游离和细胞结合的脂质体，检测到一个明显的结合位点，其Bmax为171 nmol/mg蛋白质，Kd为470 nmol/l。结合的脂质体可被过量的未标记脂质体置换，对EDTA和胰蛋白酶处理敏感，且未被二油酰磷脂酰胆碱脂质体显著竞争。然而，在无细胞的空白培养皿实验中也证明了一个具有相同特征的位点。该位点是由结合在空白培养皿上的脂质体产生的，通过大量洗涤无法去除，但可被EDTA和胰蛋白酶释放，并在过滤过程中被截留。通过离心分析技术克服了这些问题。此时非特异性结合小于1%，各种磷脂制成的脂质体对细胞结合具有剂量依赖性抑制作用。这些研究可能有助于尝试将脂质体作为载体导向肺部特定的细胞靶点。
