Original basic research

Antithrombin significantly influences platelet adhesion onto immobilized fibrinogen in an in-vitro system simulating low flow

Robert Loncar¹ , Uwe Kalina² , Volker Stoldt¹ , Volker Thomas¹ , Rüdiger E Scharf¹ and Aleksandar Vodovnik³

¹  Department of Hemostasis and Transfusion Medicine, Heinrich Heine University Medical Center Duesseldorf, Germany

²  Research ZLB Behring, Emil von Behring Strasse 76, 35041 Marburg, Germany

³  Department of Histopathology, The Calderdale Royal Hospital, HX3 0PA Halifax, UK

author email corresponding author email

Thrombosis Journal 2006, 4:19doi:10.1186/1477-9560-4-19

Published:	13 October 2006

Abstract

Background

Adhesion of platelets onto immobilized fibrinogen is of importance in initiation and development of thrombosis. According to a recent increase in evidence of a multiple biological property of antithrombin, we evaluated the influence of antithrombin on platelet adhesion onto immobilized fibrinogen using an in-vitro flow system.

Methods

Platelets in anticoagulated whole blood (29 healthy blood donors) were labelled with fluorescence dye and perfused through a rectangular flow chamber (shear rates of 13 s^-1 to 1500 s^-1). Platelet adhesion onto fibrinogen-coated slips was assessed using a fluorescence laser-scan microscope and compared to the plasma antithrombin activity. Additionally the effect of supraphysiological AT supplementation on platelets adhesion rate was evaluated.

Results

Within a first minute of perfusion, an inverse correlation between platelet adhesion and plasma antithrombin were observed at 13 s^-1 and 50 s^-1 (r = -0.48 and r = -0.7, p < 0.05, respectively). Significant differences in platelet adhesion related to low (92 ± 3.3%) and high (117 ± 4.1%) antithrombin activity (1786 ± 516 U vs. 823 ± 331 U, p < 0.05) at low flow rate (13 s^-1, within first minute) have been found. An in-vitro supplementation of whole blood with antithrombin increased the antithrombin activity up to 280% and platelet adhesion rate reached about 65% related to the adhesion rate in a non-supplemented blood (1.25 ± 0.17 vs. 1.95 ± 0.4 p = 0.008, respectively).

Conclusion

It appears that antithrombin in a low flow system suppresses platelet adhesion onto immobilized fibrinogen independently from its antithrombin activity. A supraphysiological substitution of blood with antithrombin significantly reduces platelet adhesion rate. This inhibitory effect might be of clinical relevance.