Kanai M, Murata Y, Mabuchi Y, Kawahashi N, Tanaka M, Ogawa T, Doi M, Soji T, Herbert D C
Department of Anatomy, Nagoya City University Medical School, Japan.
Anat Rec. 1996 Feb;244(2):175-81. doi: 10.1002/(SICI)1097-0185(199602)244:2<175::AID-AR5>3.0.CO;2-0.
While phagocytosis by Kupffer cells (stellate perisinusoidal macrophages) is well known and that by endothelial cells also is thought to occur under certain conditions, the uptake of large particles by hepatocytes has not been well studied. We reported previously the selective phagocytic uptake of material by hepatocytes using egg lecithin-coated silicon particles. In the present work, we describe more precisely this process following the injection of lecithin-coated polystyrene beads. Additionally, we consider the possible significance of the transcytotic action by endothelial cells.
Polystyrene latex beads (240 nm in diameter) composed of two layers of polystyrene and methyl methacrylate with a central void cavity and diameter of 140 nm were injected into male Wister-Imamichi rats. The injections were administered through the hepatic portal vein in a volume of 3 ml (concentration of the lecithin-coated or uncoated beads was 2 mg/ml). Controls received the lecithin alone at a concentration of 2 mg/ml. Liver samples were taken 5, 10, or 15 min after injection, fixed, and processed for ultrastructural analysis.
Both lecithin-coated and noncoated beads were mainly incorporated in the Kupffer cells as well as in the endothelial cells. Bristle-coated invaginations were observed in the uptake by both cell types; however, noncoated invaginations were also active in the endothelial cells, especially on the surface facing the perisinusoidal space of Disse. Only coated beads were observed within the space or in the hepatocytes. Once taken up by the hepatocytes, the lecithin-coated beads were found either within lysosomes or in a free state in the cytoplasm.
Uptake of 240 nm lecithin-coated polystyrene beads was observed by Kupffer cells, endothelial cells and hepatocytes. These beads were considered to be transported across the endothelial cells by transcytosis. Pseudopodia and bristle-coated invaginations were not employed by the hepatocytes when incorporating the beads.
虽然库普弗细胞（星状肝血窦周巨噬细胞）的吞噬作用广为人知，并且内皮细胞的吞噬作用在某些条件下也被认为会发生，但肝细胞对大颗粒的摄取尚未得到充分研究。我们之前报道过利用卵磷脂包被的硅颗粒，肝细胞对物质的选择性吞噬摄取。在本研究中，我们在注射卵磷脂包被的聚苯乙烯珠后更精确地描述了这一过程。此外，我们考虑了内皮细胞转胞吞作用的可能意义。
将由两层聚苯乙烯和甲基丙烯酸甲酯组成、中心有空腔且直径为140nm、直径为240nm的聚苯乙烯乳胶珠注入雄性Wister-Imamichi大鼠体内。通过肝门静脉以3ml的体积进行注射（卵磷脂包被或未包被珠的浓度为2mg/ml）。对照组接受浓度为2mg/ml的单独卵磷脂。在注射后5、10或15分钟采集肝脏样本，固定并进行超微结构分析。
卵磷脂包被和未包被的珠子主要被库普弗细胞以及内皮细胞摄取。在两种细胞类型的摄取过程中均观察到刷毛包被的内陷；然而，未包被的内陷在内皮细胞中也很活跃，尤其是在面向狄氏间隙的肝血窦周空间的表面。仅在间隙内或肝细胞中观察到包被的珠子。一旦被肝细胞摄取，卵磷脂包被的珠子要么在溶酶体内，要么在细胞质中呈游离状态。
观察到库普弗细胞、内皮细胞和肝细胞摄取了240nm的卵磷脂包被的聚苯乙烯珠。这些珠子被认为是通过转胞吞作用穿过内皮细胞的。肝细胞摄取珠子时未采用伪足和刷毛包被的内陷。
