The reversible aggregation of red blood cells (RBCs) continues to be of the basic science and clinical interest. Recently it has been reported about a specific binding between fibrinogen and unknown erythrocyte glycoprotein receptors. The aim of this study was to investigate whether the red blood cell aggregation (RBCA) include the cell-cell interaction using the membrane receptors that bind such ligands as fibrinogen or fibronectin. To test this hypothesis the RBCs were incubated with monaframthe drug of the monoclonal antibodies against glycoprotein (GP) IIb/IIIa, with the GPIIb-IIIa receptor antagonist tirofiban, epifibatide and with the fibrinogen inhibiting peptide. It has been found that the RBC incubation with monafram resulted in a marked RBCA decrease mainly in persons with high level of aggregation. Another research session has shown that RBC incubation with fibronectin was accompanied by a significant RBCA rise. The monafram addition to red cell incubation medium resulted in a significant RBCA lowering. The cell incubation with tirofiban and epifibatide issued in RBCA decrease. The similar results were obtained when RBCs were incubated with the fibrinogen inhibiting peptide. Although monafram, tirofiban, eptifibatide and the fibrinogen inhibiting peptide were related to fibrinogen function they didn't inhibit RBCA completely. Therefore, under moderate and low red blood cell aggregation the cell binding is probably related to nonspecific mode. It seems evident that the specific and nonspecific modes of red blood cell aggregate formation could co-exist. Additional theoretical and experimental investigations in this area are needed.

It is commonly known that red blood cell (RBC) tendency to reversibly aggregate contribute to the unique flow properties of blood. The fibrinogen-induced aggregation is primarily based on non-specific processes. Nevertheless, recent investigations disclosed a possibility of the specific fibrinogen-RBC binding, however, its role in RBC aggregation remains unclear. We conducted a study to determine whether this specific interaction is essential for natural RBC aggregation. The influence of glycoprotein (GP) IIb-IIIa inhibitor, monafram, on RBC aggregation was compared in RBC suspensions and in whole blood samples from healthy volunteers and, in addition, from patients with systemic lupus erythematosus (SLE) using laser-light backscattering detection and optical tweezers. The effect of monafram on normal RBC aggregation was detectable only in the early phase of intercellular interactions and it involved a deceleration of the aggregation, which was equally expressed in native blood samples and RBC suspensions based on platelet-free plasma. Additionally, in SLE patients, monafram weakened the strength of paired RBC aggregates in platelet-free suspensions. In healthy subjects, strengthened aggregates were found mainly in platelet-containing bulk RBC suspensions. These findings suggest that normal specific fibrinogen-RBC binding could lead to early accelerated formation of RBC aggregates, which could increase possible beneficial effects of reversible RBC aggregation. The strength of RBC aggregates could be modified by platelets in normal subjects and by specific fibrinogen-RBC binding in SLE patients.