Fibronectin dependent macrophage fibrin binding
SD Blystone, LK Weston and JE Kaplan
Department of Physiology and Cell Biology, Albany Medical College, NY
12208.
Plasma fibronectin has been shown to increase the binding of fibrin monomer
to macrophages in vitro. In the present study we began characterization of
the mechanism underlying this fibronectin activity. Fragments of
fibronectin containing the amino terminus enhanced macrophage fibrin
binding to the same extent as intact fibronectin on an equimolar basis.
However, fibronectin fragments containing the gelatin-binding domain or the
cell-binding domain, but lacking the amino terminus, had no effect on
fibrin binding. Fibronectin enhanced fibrin binding was not affected by the
addition of synthetic peptides containing the RGD adhesion sequence. The
ability of fibronectin to augment fibrin binding remained after
paraformaldehyde fixation of macrophage monolayers. Fixation did not alter
the basal levels of fibrin binding by macrophages. Preincubation of
macrophages with exogenous fibronectin did not increase the binding of
fibrin. Fibronectin enhanced fibrin binding remained unaltered after the
removal of endogenous cell surface fibronectin by capping with F(ab')2
fragments of antibodies to fibronectin. These results suggest that the
amino terminus of fibronectin supports the attachment of fibrin to
macrophages by an initial fluid-phase interaction that precedes cellular
binding and does not require a cellular response.
Volume 78,
Issue 11,
pp. 2900-2907,
12/01/1991
Copyright © 1991 by The American Society of Hematology
