Abstract Number: PB1897
Meeting: ISTH 2020 Congress
Background: aPS/PT antibodies confer additional risk for thrombembolic events and pregnancy loss to the usual aPL profile(LA, aCL, and anti- β2GPI antibodies). The relative contribution of aβ2GPI and aPS/PT antibodies in determining anticoagulant activity in APS patients is unknown.
Aims: We aimed at separation of aβ2GPI and aPS/PT antibodies from tetra positive APS patients, to test their contribution to anticoagulant activity by thrombin generation (TG).
Methods: aβ2GPI antibodies were purified from 24 and aPS/PT antibodies were from 4 tetera positive (LA+, aCL+, aβ2GPI +, aPS/PT+ ) APS patients by immune affinity chromatography. The antigenic specificity of eluted antibodies was determined using ELISA. TG in tissue factor-triggered platelet-poor plasma was measured with the calibrated automated thrombogram method and purified aβ2GPI and aPS/PT antibodies and tris buffer were spiked into normal plasma to obtain TG curves.
Results: The mean concentration of purified aβ2GPI is 65.79±34.48 µg/mL, aPT is 37.4 µg/mL. As shown in figure 1, NNP+ aPS/PT TG curve showed anticoagulated characteristics in all five parameters, compared to NNP+ aβ2GPI and NP+TRIS, NNP+ aPS/PT showed longest lag time (4.5 ±1.3 VS 3.5±0.6 VS 2.6±0.3 min, p< 0,0001), highest ETP (1450±79 VS 1427±123 vs 1338±87 nM per min, p=0,0090), lowest peak(143±11 vs 187±31 vs 166 ± 20 nM, p=0,0008), longest time to peak (8.9 ± 1.7 vs 6.1 ± 0.8 vs 5.9 ± 0.8 min, p=-0.002), lowest velocity index (33.5±8.2 vs 76.1±24.9 vs 52.1 ± 13.7nM/min, p < 0,0001). Compare to NNP+ aβ2GPI group, NNP+ aPS/PT group showed significantly lower peak (p=0.003), longer time to peak (p=0.004), and lower velocity index (p=0.0005).
Conclusions: Immune purified aPS/PT and aβ2GPI cause significantly reduced thrombin generation of normal pooled plasma in vitro. The anticoagulant effect of APS/PT+ antibodies was significantly stronger than that of aβ2GPI antibodies.
To cite this abstract in AMA style:Bison E, Pontara E, Cattini M, Cheng C-, Denas G, Pengo V. Effect of Immune-Purified aβ2-Glycoprotein I (aβ2GPI) and Anti Phosphatidylserine/Prothrombin (aPS/PT) Antibodies on Thrombin Generation [abstract]. Res Pract Thromb Haemost. 2020; 4 (Suppl 1). https://abstracts.isth.org/abstract/effect-of-immune-purified-a%ce%b22-glycoprotein-i-a%ce%b22gpi-and-anti-phosphatidylserine-prothrombin-aps-pt-antibodies-on-thrombin-generation/. Accessed January 23, 2022.
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