Martínez-Flores José A, Serrano Manuel, Pérez Dolores, Lora David, Paz-Artal Estela, Morales José M, Serrano Antonio
Department of Immunology, Instituto de Investigación Hospital Universitario 12 de Octubre, Madrid, Spain.
Epidemiology Section, Instituto de Investigación Hospital Universitario 12 de Octubre, Madrid, Spain.
J Immunol Methods. 2015 Jul;422:51-8. doi: 10.1016/j.jim.2015.04.002. Epub 2015 Apr 10.
Patients with antiphospholipid syndrome (APS) have a hypercoagulable condition associated with the presence of antiphospholipid autoantibodies (aPL). Consensus antibodies for diagnosis are lupus anticoagulant, anti-beta2 glycoprotein I (B2GPI) and anticardiolipin (IgG or IgM). Circulating immunocomplexes (CIC) of B2GPI associated with IgM or IgG were reported. Isolated IgA aB2GPI antibodies have achieved high diagnostic value although specific CIC of B2GPI bounded to IgA (B2A-CIC) has still not been described. CIC detection assays are mainly based on interaction with complement and are not appropriate to detect B2A-CIC because IgA does not fix complement using the classical pathway.
Sera from healthy blood donors (N= 247) and from patients with thrombosis background and isolate positive for IgA aB2GPI (N = 68) were studied in a case-control study. Two methods were applied, these being a capture ELISA to quantify specific B2A-CIC and quantification of total IgA anti-B2GPI after dissociating CIC.
B2A-CIC values in APS-patients were 19.27 ± 2.6 AU vs 6.1 ± 0.4 AU in blood donors (p < 0.001). There were 36.4% B2A-CIC positive patients (cutoff 21 AU) versus 5.5% in blood donors (p < 0.001). Dissociated IgA aB2GPI levels (total IgA aB2GPI) were 146.8 ± 10.8 IU/mL in patients vs. 22.4 IU/mL in controls (p < 0.001). B2A-CIC was independent of B2GPI and autoantibodies IgA aB2GPI serum levels.
B2A-CIC can be identified and quantified in an easy and reproducible manner using two complement-independent methods. The use of these tests in prospective studies will allow better understanding of the prognosis and outcome of patients.
抗磷脂综合征（APS）患者存在与抗磷脂自身抗体（aPL）相关的高凝状态。诊断的共识抗体为狼疮抗凝物、抗β2糖蛋白I（B2GPI）和抗心磷脂（IgG或IgM）。有报道称存在与IgM或IgG相关的B2GPI循环免疫复合物（CIC）。尽管尚未描述与IgA结合的B2GPI特异性CIC（B2A - CIC），但分离出的IgA aB2GPI抗体已具有较高的诊断价值。CIC检测方法主要基于与补体的相互作用，不适用于检测B2A - CIC，因为IgA不通过经典途径固定补体。
在一项病例对照研究中，对健康献血者（N = 247）以及有血栓形成背景且IgA aB2GPI检测呈阳性的患者（N = 68）的血清进行了研究。应用了两种方法，一种是捕获ELISA法来定量特异性B2A - CIC，另一种是在解离CIC后定量总IgA抗B2GPI。
APS患者的B2A - CIC值为19.27±2.6 AU，而献血者为6.1±0.4 AU（p < 0.001）。B2A - CIC阳性患者占36.4%（临界值为21 AU），而献血者中为5.5%（p < 0.001）。患者中解离后的IgA aB2GPI水平（总IgA aB2GPI）为146.8±10.8 IU/mL，对照组为22.4 IU/mL（p < 0.001）。B2A - CIC与B2GPI及自身抗体IgA aB2GPI血清水平无关。
使用两种不依赖补体的方法能够以简便且可重复验证的方式识别和定量B2A - CIC。在前瞻性研究中应用这些检测方法将有助于更好地了解患者的预后和转归。
