Fibrinogen, a modulator of erythrocyte adhesion to vascular endothelium.

The high incidence of thrombosis in inflammatory states and previous reports of increased adhesion of erythrocytes to endothelial cells in diabetes mellitus and sickle cell anemia prompted us to study the effect of fibrinogen and fibronectin on erythrocyte-endothelial interactions. Purified human fibrinogen enhanced erythrocyte adhesion in a concentration-dependent fashion. Erythrocytes from normal subjects, diabetics, and patients with sickle cell anemia were studied. The ratio between the adhesion of normal red cells in a 4 gm/L fibrinogen to adhesion in buffer without fibrinogen was 3.6 (p less than 0.001). Fibronectin also increased red cell adhesion but the effect was less than that of fibrinogen. The addition of fibronectin to fibrinogen limited the enhancing effect of fibrinogen, although the effect of the mixture was greater than that of fibronectin alone (p less than 0.05). Anti-von Willebrand factor and antifibronectin, which react with endothelial cells, also produced an increase in erythrocyte adhesion. The potentiation of adhesion by fibrinogen was also seen in experiments using red cells from patients with sickle cell anemia or diabetes mellitus. These observations provide possible mechanisms for the involvement of plasma proteins in vascular occlusive diseases.