Evaluation of platelet aggregation in the presence of antiphospholipid antibodies: anti-β2GP1 and anticardiolipin.

INTRODUCTION

The antiphospholipid syndrome (APS) is an autoimmune condition characterized by recurrent arterial and venous thrombosis, besides obstetric complications. The pathogenesis is associated with the presence of antiphospholipid and/or anti-b2-glicoprotein I (anti-b2GPI) antibodies that appear to change the anticoagulant activity of b2GPI. Antibody-induced dimerization of b2GPI seems to be related to the induction of platelet aggregation, contributing to the development of thrombosis in APS.

OBJECTIVES

The objective of the present study is to demonstrate the influence of antiphospholipid antibodies in platelet aggregation tests with different agonists (ADP, collagen, and adrenaline).

METHODS

We analyzed platelet aggregation tests with different agonists (ADP, collagen, adrenalin) when normal platelets were exposed to serum with different concentrations of antiphospholipid antibodies.

RESULTS

Results demonstrated a significant inhibition in adrenalin- and ADP-induced platelet aggregation curves (P < 0.05) in all antibody concentrations tested when compared to the control. The paradox between the prothrombotic state and the presence of autoantibodies that show anticoagulant activity in vitro was demonstrated in the literature, making it difficult to understand the pathophysiologic mechanism of the antiphospholipid syndrome.

CONCLUSION

Results showed that anticardiolipin and anti-b2GPI antibodies-rich serum, both of which belonging to the IgG class, can interfere with platelet aggregation curves.