Histidine-rich glycoprotein does not interfere with interactions between
antithrombin III and heparin-like compounds on vascular endothelial cells
K Shimada, A Kawamoto, K Matsubayashi and T Ozawa
Department of Medicine and Geriatrics, Kochi Medical School, Japan.
The role of histidine-rich glycoprotein in controlling heparin-like
compounds on the endothelial cell surface is still unclear. The effects of
this heparin-neutralizing protein on the interaction between antithrombin
III and cultured porcine aortic endothelial cells were examined.
Displacement of 125I-labeled antithrombin III specifically bound to
endothelial cells by unlabeled histidine-rich glycoprotein was much less
potent than that by unlabeled antithrombin III. One hundred- fold molar
excess of histidine-rich glycoprotein displaced specific 125I-antithrombin
III binding only by 20%. Furthermore, the endothelial cell-mediated
acceleration of thrombin inactivation by antithrombin III was diminished by
protamine sulfate, but was not affected by histidine- rich glycoprotein
even at a histidine-rich glycoprotein/antithrombin III molar ratio of
approximately 7:1. These data indicate that histidine-rich glycoprotein
does not interfere with the interaction of endothelial cell heparin-like
compounds with antithrombin III. Thus, it may not play an important role in
the modulation of anticoagulant activity of endothelial cells in vivo,
suggesting that the commonly accepted view of the probable function of this
protein is erroneous.
Volume 73,
Issue 1,
pp. 191-193,
01/01/1989
Copyright © 1989 by The American Society of Hematology
