Thrombosis Research Laboratory, University of Padova, Padova, Italy.
Thrombosis Research Laboratory, University of Padova, Padova, Italy; Arianna Foundation on Anticoagulation, Bologna, Italy.
Thromb Res. 2022 Oct;218:17-23. doi: 10.1016/j.thromres.2022.08.004. Epub 2022 Aug 11.
Anti-phosphatidylserine/prothrombin (aPS/PT) antibodies are the major contributor to activated Protein C resistance (APC-R) in tetra-positive thrombotic high-risk patients with Antiphospholipid Syndrome (APS).
To evaluate the role of phospholipids (PL) on aPS/PT mediated APC-R.
PATIENTS/METHODS: Total IgG were purified from plasma of 6 tetra-positive patients and IgG aPS/PT were affinity-purified from 3 of these patients. Purified material was spiked into Normal Pooled Plasma (NPP) and tested for APC-R in thrombin generation assay and in Factor Va inactivation assay using increasing amounts of phospholipids.
Total IgG showed APC-R at low PL concentration (1.5 μg/mL) that disappeared at increasing PL concentrations (5.8, 11.6 and 46.6 μg/mL). In the same way, affinity purified aPS/PT showed a robust (59 %, 52 %, 36 %) APC-R in patients #4, #5 and #6, respectively at low PL concentration (1.5 μg/mL) that was completely reversed at higher concentration (11.6 μg/mL). The inactivation of FVa by activated Protein C (aPC) was impaired in the presence of aPS/PT at low aPL concentration and reversed by increasing amounts of PL. These data point out the relevance of PL in reversing APC-R in this 'in vitro' system. The mechanism for reversal might be explained by loss of PL availability for aPC. These results may give some insight into the pathogenesis of thrombosis or suggestions for alternative treatments.
抗磷脂酰丝氨酸/凝血酶原（aPS/PT）抗体是导致四阳性血栓高危抗磷脂综合征（APS）患者活化蛋白 C 抵抗（APC-R）的主要原因。
评估磷脂（PL）在 aPS/PT 介导的 APC-R 中的作用。
患者/方法：从 6 名四阳性患者的血浆中纯化总 IgG，并从其中 3 名患者中亲和纯化 IgG aPS/PT。将纯化的物质掺入正常混合血浆（NPP）中，并在凝血酶生成试验中和使用增加的磷脂量的因子 Va 失活试验中测试 APC-R。
总 IgG 在低 PL 浓度（1.5μg/mL）下显示 APC-R，随着 PL 浓度的增加（5.8、11.6 和 46.6μg/mL）而消失。同样，亲和纯化的 aPS/PT 在患者 #4、#5 和 #6 中分别在低 PL 浓度（1.5μg/mL）下显示出强烈的（59%、52%、36%）APC-R，在较高浓度（11.6μg/mL）下完全逆转。在低 aPL 浓度下，aPC 对 FVa 的失活作用受到 aPS/PT 的影响，随着 PL 量的增加而逆转。这些数据表明 PL 在这个“体外”系统中逆转 APC-R 的相关性。逆转的机制可能是由于 PL 对 aPC 的可用性丧失。这些结果可能为血栓形成的发病机制提供一些见解或为替代治疗提供建议。
