A Monoclonal Antibody Against Platelet GPVI Impaires the Interaction Between Platelet and Collagen

Abstract number: P2136

Yu Z, Dong N, Bai X, Shen F, Shao B, Ji S, Ruan C

Collagen is one of the major components of vessel wall responsible for platelet adhesion and activation at the site of vascular injure. Glycoprotein VI (GPVI), an essential platelet collagen receptor, plays an important role in hemostasis and thrombus formation. It has been shown that impairment of GPVI function could result in a long-term antithrombotic protection and less bleeding side-effect. Thus blocking GPVI function may represent a new and safe antithrombotic method. Recently a monoclonal antibody, SZ118, against GPVI was developed and displayed a capacity to inhibit the interaction between platelet and collagen. The recombinant soluble human GPVI(rGPVI), consisting of two extracellular domains of the receptor, was expressed in E. coli and purified by affinity chromatography on Ni-NTA Resin. After immunizing Balb/C mice with the rGPVI and selecting the hybridoma cell with ELISA assay, a monoclonal antibody, SZ118, was obtained. SZ118 bound specifically to human platelet (90%), not to human leukocyte and red blood cell (2.4% and 0% respectively) by FCM analysis. SZ118 inhibited collagen-induced platelet aggregation in PRP in dose-dependent manner, nearly full inhibition being attained at the concentration of 110 ug mL^-1. Similarly SZ118 had part effect on convulxin-induced platelet aggregation, but little effect on ADP-induced aggregation. The effects of SZ118 on platelet adhesion were determined under flow conditions by perfusing whole blood at 1000 s^-1 on insoluble fibrillar equine collagen. When anticoagulated whole blood was treated with 50 ug mL^-1 SZ118, the number and size of platelet aggregates were greatly reduced, the coverage area was also markedly decreased. Thus SZ118 impaired the interaction of GPVI with collagen, inhibited collagen-induced platelet aggregation and blocked platelet adhesion on collagen in flow condition.