Fixed washed platelet adhesion to collagen using collagen coated glass bead column

Effect of plasma fibronectin on the adhesion

Abstract

An effect of plasma fibronectin (FN) on the adhesion of human fixed washed platelets (FWP) to collagen was evaluated. FWP did not adhere to denatured collagen (heated collagen, gelatin agarose). The percent adhesion to collagen column (1300μg) was 51% at 5ml/min flow rate. The addition of purified fibronectin (FN) decreased the degree of adhesion to collagen dose dependently; 34% (FN 31μg/ml), 29% (62μg/ml), 16% (125μg/ml) and 3% (250μg/ml). The inhibitory effect of FN on the platelet adhesion was also observed by pretreatment of the collagen beads with purified FN. The addition of purified von Willebrand factor (vWF), however, increased the adhesion and the enhancing effect of vWF on the adhesion was observed at higher flow rate conditions. Pretreatment of FWP with anti-FN antibody or anti vWF: Ag antibody did not change the degree of adhesion to collagen.
Plasma FN bound to collagen in suspension and the affinity of FN to collagen was greater than that of vWF: Ag; 97% FN and 60% vWF: Ag bound to 250μg/ml collagen. The binding of ritocetin cofactor (vWF: RCo) to collagen (12.5-100μg/ml) was partially inhibited by FN, but both proteins bound completely to the collagen at 200-500μg/ml.
These data suggested that the adhesion of FWP to collagen is not mediated through plasma FN, while plasma vWF controls the adhesion at high flow rates.