Receptor-mediated transcytosis of transferrin through blood-brain
barrier endothelial cells.
Laurence, Descamps, Dehouck Marie-Pierre, Torpier Gerard, and
Cecchelli Romo.
INSERM U325-SERLIA, Institut Pasteur, 59019 Lille Cedex, France,
Universite des Sciences et Technologies de Lille I, 59655 Villeneuve
d'Ascq Cedex, France
APStracts 2:0412H, 1995.
A cell culture model of the blood-brain barrier consisting of a
coculture of bovine brain capillary endothelial cells (BBCECs) and
astrocytes have been used to examine the mechanism of iron transport
to the brain. Binding experiments showed that BBCECs express 35 000
high affinity (Kd=11.3 +/- 2.1 nM) transferrin (Tf) receptors per
cell. In contrast to apoTf, we observed a specific transport of
holoTf across BBCECs. This transport was inhibited completly at low
temperature. Moreover, the anti-Tf receptor antibody (OX-26)
competitively inhibited holoTf uptake by BBCECs. Pulse chase
experiments demonstrated that only 10 % of Tf was recycled to the
luminal side of the cells, whereas the majority of Tf was
transcytosed to the abluminal side ; double labeling experiments
clearly demonstrated that iron crosses BBCECs bound to Tf. No
intraendothelial degradation of Tf was observed, suggesting that the
intraendothelial pathway through BBCECs bypasses the lysosomal
compartment. These results clearly show that the iron-Tf complex is
transcytosed across brain capillary endothelial cells by a receptor
-mediated pathway without any degradation.
Received 3 November 1994; accepted in final form 5 September
1995.
APS Manuscript Number H983-4.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 23 September 1995.