Zhang Y, Pardridge W M
Department of Medicine, UCLA School of Medicine, Los Angeles, CA 90095-1682, USA.
J Neuroimmunol. 2001 Mar 1;114(1-2):168-72. doi: 10.1016/s0165-5728(01)00242-9.
Dextrans and albumin exit brain from blood following intra-cerebral injection by a slow process of convection with a halftime of 10-12 h in the rat. The present studies show that immunoglobulin G (IgG) molecules rapidly efflux from brain to blood across the blood-brain barrier (BBB) following intracerebral injection. The IgG efflux is rapid with a halftime of 48 min in the rat. The efflux of [3H]mouse IgG(2a) from brain to blood is competitively inhibited by intracerebral injection of unlabeled mouse IgG molecules, but is not inhibited by intracerebral injection of comparable doses of unlabeled rat albumin. The IgG efflux system has characteristics of an Fc receptor, as the efflux from brain is competitively inhibited by Fc fragments but is not blocked by F(ab')(2) fragments. Precipitation of brain homogenate by trichloroacetic acid indicates there is no significant metabolism of the IgG molecules during the experimental time period. In conclusion, these studies provide evidence for a BBB Fc receptor that mediates the reverse transcytosis of IgG molecules in the direction of brain to blood.
右旋糖酐和白蛋白在大鼠脑内注射后，通过缓慢的对流过程从血液中排出脑外，半衰期为10 - 12小时。目前的研究表明，脑内注射后，免疫球蛋白G（IgG）分子可迅速从脑内穿过血脑屏障（BBB）流入血液。在大鼠中，IgG流出速度很快，半衰期为48分钟。脑内注射未标记的小鼠IgG分子可竞争性抑制[3H]小鼠IgG(2a)从脑到血液的流出，但脑内注射同等剂量的未标记大鼠白蛋白则无抑制作用。IgG流出系统具有Fc受体的特征，因为脑内流出可被Fc片段竞争性抑制，但不被F(ab')(2)片段阻断。三氯乙酸沉淀脑匀浆表明，在实验时间段内IgG分子没有明显代谢。总之，这些研究为血脑屏障Fc受体介导IgG分子从脑到血液方向的逆向转胞吞作用提供了证据。
