Antiphospholipid syndrome

Venom

Viper Venoms

Biochemistry

Coagulation

Immunology

Lupus anticoagulant

Affinity chromatography

Enzyme

Internal medicine

Medicine

Chemistry

Snake venom

Clotting time

Antibody

Anticoagulant

Journal of Thrombosis and Haemostasis

The concurrent presence of lupus anticoagulant, anticardiolipin, and anti β2-glycoprotein I antibodies (triple positive profile) identifies patients at high risk of thromboembolic events. These patients are also positive for anti-phosphatidyl-serine/prothrombin antibodies (tetra-positive profile).Understand which antibody among anti-β2-glycoprotein I and anti-phosphatidyl-serine/prothrombin is responsible for lupus anticoagulant activity.Affinity purified anti-β2-glycoprotein I antibodies from plasma of 14 tetra-positive patients spiked into normal pooled plasma were tested.Anti-β2-glycoprotein I antibodies did not prolong the diluted Russell viper venom time and silica clotting time (median ratio 0.98, interquartile ratio [IQR] 0.9-1.06; and 1.0, IQR 0.91-1.03, respectively). Anticoagulant activity remained in the flow-through that was deprived of anti-β2 glycoprotein I antibodies (median ratio 1.88, IQR 1.58-2.77; and 1.75, IQR 1.17-2.9, respectively). This material was loaded on size-exclusion chromatography Sephacryl S-300 column and showed that anticoagulant activity and anti-phosphatidyl-serine/prothrombin antibodies coeluted in the same fractions. Besides, the flow through was poured into a prothrombin affinity column. Protein yield in three patients ranged from 54 to 91 μg/mL and showed strong positivity in phosphatidyl-serine/prothrombin ELISA. The affinity purified material prolonged the coagulation time of normal pooled plasma: the diluted Russell viper venom ratio in the three patients was 2.09, 1.21, and 1.35; that of silica clotting time was 2.05, 1.5, and 2.13. In conclusion, under the assay conditions used, anticoagulant activity in tetra-positive antiphospholipid syndrome patients may largely be attributable to anti-phosphatidyl-serine/prothrombin antibodies.

Tetra positive thrombotic antiphospholipid syndrome: Major contribution of anti‐phosphatidyl‐serine/prothrombin antibodies to lupus anticoagulant activity