scholarly journals Biosensor Analysis of β2-Glycoprotein I–Reactive Autoantibodies: Evidence for Isotype-Specific Binding and Differentiation of Pathogenic from Infection-Induced Antibodies

2007 ◽  
Vol 53 (6) ◽  
pp. 1137-1143 ◽  
Author(s):  
Jochen Metzger ◽  
Philipp von Landenberg ◽  
Marcus Kehrel ◽  
Alexander Buhl ◽  
Karl J Lackner ◽  
...  
Keyword(s):  
Lupus Erythematosus ◽  
Specific Binding ◽  
Parvovirus B19 ◽  
Laboratory Diagnosis ◽  
Antiphospholipid Antibody ◽  
Serum Samples ◽  
Additional Information ◽  
Glycoprotein I ◽  
Spr Biosensor ◽  
Biosensor System

Abstract Background: For the laboratory diagnosis of the antiphospholipid syndrome (APS) we developed a biosensor with the ability to distinguish between disease-relevant anti-β2-glycoprotein I (β2GPI) autoantibodies (anti-β2GPI) and pathogen-specific β2GPI cross-reactive antibodies that occur transiently during infections. Methods: We used a surface plasmon resonance (SPR) biosensor device. For the detection of anti-β2GPI in serum samples, affinity-purified human β2GPI was covalently attached to a functionalized n-alkanethiol self-assembling monolayer on the biosensor chip. After verifying the specificity of the biosensor system with a panel of monoclonal antibodies to β2GPI, we analyzed sera from healthy donors and patients suffering from APS, systemic lupus erythematosus (SLE), syphilis, or parvovirus B19 infections. The SPR results were compared with β2GPI-specific ELISA. Results: Using the SPR biosensor, we recorded antigen binding curves with response levels in the range of 50–500, resonance units (RU) for anti-β2GPI ELISA-positive APS patient sera. The amplitudes of the antiphospholipid antibody (APL) responses in the biosensor correlated with the overall IgG and IgM anti-β2GPI ELISA titers with a correlation coefficient of 0.87. Moreover, we observed immunoglobulin isotype-specific association and dissociation profiles for APL binding of different APS patient sera to the biosensor-immobilized β2GPI. In contrast to APS patient samples, no significant anti-β2GPI binding (response levels <35 RU) was observed in samples from healthy individuals or from patients suffering from SLE, syphilis, or parvovirus B19 infection. Conclusions: The SPR biosensor system enables specific detection of APS-associated β2GPI-reactive APL and differentiation from β2GPI cross-reactive antibodies that occur frequently during acute infections. The established association/dissociation plot for anti-β2GPI responses in APS patient sera gives additional information regarding the influence of anti-β2GPI IgG and IgM isotype distribution.

scholarly journals Antiphospholipid antibody levels in early systemic lupus erythematosus: are they associated with subsequent mortality and vascular events?

Rheumatology ◽  
2019 ◽  
Vol 59 (1) ◽  
pp. 146-152 ◽  
Author(s):  
Charis Pericleous ◽  
Amrita D’Souza ◽  
Thomas McDonnell ◽  
Vera M Ripoll ◽  
Oliver Leach ◽  
...  
Keyword(s):  
Lupus Erythematosus ◽  
Antiphospholipid Antibody ◽  
Serum Samples ◽  
Vascular Events ◽  
Main Site ◽  
Pregnancy Morbidity ◽  
Glycoprotein I ◽  
Kaplan Meier ◽  
History Of ◽  
Domain I

Abstract Objectives aPL are present in between 20 and 30% of patients with SLE. They can cause vascular events (VE) or pregnancy morbidity. aCL and anti-beta-2-glycoprotein I (anti-β2GPI) are measured in clinical practice. Domain I (DI) of β2GPI is the main site for aPL binding. We investigated the prevalence of IgG anti-DI, aCL and anti-β2GPI antibodies in early SLE and their association with mortality and development of VE. Methods Samples from 501 patients with SLE that had been obtained and stored early during their disease were tested for IgG anti-DI, aCL and anti-β2GPI antibodies by ELISA. LA status and history of VE were obtained by reviewing medical records. Kaplan–Meier analysis was used to investigate mortality and occurrence of VE, comparing groups with and without aPL in early disease. Results Of 501 patients, 190 (38%) had at least one of these aPL, of whom 112 had anti-DI alone. Of 276 patients with complete vascular history, 83 had experienced VE. The 39 patients who were double or triple-ELISA-positive for any combination of the three aPL were more likely to have or develop lupus anticoagulant (P<0.0001) than those who were single-ELISA-positive or negative. In Kaplan–Meier analysis, they showed a trend towards developing more VE (P = 0.06). Conclusion IgG anti-DI antibodies were present in early serum samples from 29% of patients and were more common than IgG aCL or anti-β2GPI. There was some evidence suggesting that double or triple-ELISA-positivity for these antibodies identified a group with worse outcomes.

IgA Anticardiolipin Antibodies – Relation with other Antiphospholipid Antibodies and Clinical Significance

1998 ◽  
Vol 79 (02) ◽  
pp. 282-285 ◽  
Author(s):  
Josep Ordi-Ros ◽  
Francesc Monegal-Ferran ◽  
Nuria Martinez ◽  
Fina Cortes-Hernandez ◽  
Miquel Vilardell-Tarres ◽  
...  
Keyword(s):  
Lupus Erythematosus ◽  
Antiphospholipid Antibodies ◽  
Fetal Loss ◽  
Cross Sectional Study ◽  
Anticardiolipin Antibodies ◽  
Antiphospholipid Antibody ◽  
Antiphospholipid Antibody Syndrome ◽  
Serum Samples ◽  
Cross Sectional ◽  
Vein Thrombosis

SummaryObjective: To evaluate the usefulness of IgA antiphospholipid antibodies as markers of thrombosis and/or antiphospholipid antibody syndrome. Patients and Methods: A cross-sectional study design in a tertiary, university-based, autoimmune reference hospital. Seven-hundred ninety-five patients classified into five different groups – autoimmune diseases (255), deep vein thrombosis (153), transitory ischemic attacks (108), obstetric complications (196), infectious diseases (83) and controls (81) – were tested for IgA, IgG and IgM aPL, and lupus anticoagulant. Plasma and serum samples were drawn for detection of aPL using an internationally standardized ELISA method and LA was carried out using coagulometric assays. Results: True IgA aPL were found only in two patients with systemic lupus erythematosus; these patients were also positive to IgG aPL. Conclusion: The incidence of true positivity to IgA anticardiolipin antibodies is extremely low. Their determination was not helpful in diagnosing the antiphospholipid syndrome or in explaining thrombotic events or aPL related manifestations – fetal loss – in the groups studied.

A Potential Antithrombotic Trick for an Old Drug: Quinine Inhibits the Binding of Antiphospholipid Antibody-β2-Glycoprotein I Immune Complexes to Phospholipid Bilayers in Vitro

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 3423-3423
Author(s):  
Ervis Bezati ◽  
Xiao Xuan Wu ◽  
Jacob H. Rand
Keyword(s):  
Lupus Erythematosus ◽  
Immune Complexes ◽  
Conflicts Of Interest ◽  
Disease Process ◽  
Phospholipid Bilayers ◽  
Antiphospholipid Antibody ◽  
Disruptive Effect ◽  
Glycoprotein I ◽  
Drug Concentrations

Abstract Abstract 3423 Background: Quinine, an old drug extracted from bark of the cinchona tree, was the first effective antimalarial. Hydroxychloroquine (HCQ), a synthetic antimalarial developed over 60 years ago was subsequently found to be effective for treating autoimmune disorders and is widely used to treat systemic lupus erythematosus (SLE). Observational clinical studies have indicated that HCQ is associated with reduced risk of thrombosis in SLE and the antiphospholipid (aPL) syndrome (APS). Autoimmune recognition of β2-glycoprotein I (β2GPI) by aPL autoantibodies is a key thrombogenic step in the mechanism for APS. We recently demonstrated that HCQ targets aPL immune complexes and disrupts their assembly on membranes. Objective: Since quinine shares structural similarities to HCQ, we wondered whether it might have a similar effect on aPL immune complexes in vitro. Furthermore, structural differences between the two drugs could affect their activities and provide valuable information on therapeutic targeting of APS disease process. Methods: Phospholipid bilayers containing 70% phosphatidyl choline (PC) and 30 % phosphatidyl serine (PS) were formed on reflective silicon slides. Adsorption of β2GPI and the formation of aPL-β2GPI immune complexes on the supported lipid bilayers were measured using ellipsometry. Dose response of quinine and HCQ were performed and adsorption was measured in real time. The efficacy of the two drugs at desorbing immune complexes was quantified by half maximal effective concentrations (EC50) values. Experiments were also performed to gauge the ability of the drugs at preventing complex formation. Furthermore, atomic force microscopy (AFM) was used to gauge the morphological changes associated with addition of quinine to lipid-supported aPL-β2GPI immune complexes. Results: Quinine inhibited the formation of immune complexes with a higher efficacy than HCQ at equivalent drug concentrations of 0.2 mg/mL (0.192 ± 0.025 μg/cm2 for quinine vs. 0.352 ± 0.011 μg/cm2 for HCQ, p<0.001; for untreated immune complexes, 0.447 ± 0.013 μg/cm2) (Figure 1A). EC50 values for desorption of phospholipid-bound β2GPI-aPL IgG immune complexes revealed that the concentrations of quinine required for desorption of 50% of immune complexes (0.139 ± 0.003 mg/mL for quinine vs. 0.580 ± 0.006 mg/mL for HCQ, p<0.001) and β2GPI (0.129 ± 0.004 mg/mL for quinine vs. 0.440 ± 0.040 mg/mL for HCQ, p<0.001) were significantly lower than those for HCQ (Figure 1B). Furthermore, AFM experiments revealed that addition of quinine disintegrated immune complexes bound to phospholipid bilayers. Conclusions: Quinine is more effective than HCQ in impeding the formation of aPL-β2GPI immune complexes in vitro and in disintegrating immune complexes after they form. The disruptive effect that quinine and HCQ have on immune complexes suggests that the quinolone core of the molecule is an essential moiety conferring unique pharmacologic properties to the two drugs. Quinine and analogous molecules may offer novel approaches to targeting the APS disease mechanism and to reducing the thrombotic complications of APS without the inherent hemorrhagic risks of anticoagulant therapy. Disclosures: No relevant conflicts of interest to declare.

Species Specificity of Anti-β2 Glycoprotein I Autoantibodies and Its Relevance to Anticardiolipin Antibody Quantitation

1996 ◽  
Vol 75 (05) ◽  
pp. 725-730 ◽  
Author(s):  
J Arvieux ◽  
L Darnige ◽  
E Hachulla ◽  
B Roussel ◽  
J C Bensa ◽  
...  
Keyword(s):  
Lupus Erythematosus ◽  
Binding Sites ◽  
Protein A ◽  
Anticardiolipin Antibody ◽  
Species Specificity ◽  
Antiphospholipid Antibody ◽  
Antiphospholipid Antibody Syndrome ◽  
Negative Results ◽  
Glycoprotein I ◽  
Marked Preference

SummarySome patients suspected of having antiphospholipid antibody syndrome (APS) were found to be positive for anti-β2 glycoprotein I (β2GPI) antibodies despite negative results for antibodies to cardiolipin (ACA). Since the major source of β2GPI in the ACA assay is animal (usually bovine) serum, we studied the influence on ACA quantitation of the species specificity of anti-β2GPI antibodies from patients with various autoimmune disorders, mostly systemic lupus erythematosus and primary APS. Ninety-seven sera were selected based on IgG (n = 76) or IgM (n = 64) positivity by ELISA using γ-irradiated plates coated with human or bovine purified β2GPI. A higher proportion of IgM (43.7%) than IgG (7.9%) reacted to human, but not bovine, β2GPI. Furthermore, from the samples reactive to both proteins, the ratio of antibody level against bovine to that against human β2GPI was 1.08 ± 0.58 for IgG and 0.58 ± 0.3 for IgM (p <10−5). IgG and IgM ACA were detected in 78 and 40 sera, respectively; concordance between the two ELISAs for ACA and anti-β2GPI antibodies was 94% for IgG and 75% for IgM. Out of 28 IgM showing recognition restricted to human β2GPI, 21 were missed by the ACA assay, possibly because of lower concentrations of β2GPI in those patients’ sera. The antibody reactivity pattern towards human and bovine β2GPI of individual sera showed no variation with time and was related to the relative antibody avidity for each protein. A murine anti-human β2GPI monoclonal antibody, 9G1, that cross-reacts with bovine β2GPI, competed to a large extent with the patients’ anti-β2GPI antibody binding sites whatever isotype involved or protein recognized. Therefore, anti-β2GPI antibodies of IgM isotype display a marked preference for human compared to bovine β2GPI responsible for frequent inconsistencies in the ACA assay.

scholarly journals Associations with thrombosis are stronger for antiphosphatidylserine/prothrombin antibodies than for the Sydney criteria antiphospholipid antibody tests in SLE

Lupus ◽  
2021 ◽  
pp. 096120332110145
Author(s):  
Sahwa Elbagir ◽  
Giorgia Grosso ◽  
NasrEldeen A Mohammed ◽  
Amir I Elshafie ◽  
Elnour M Elagib ◽  
...  
Keyword(s):  
Risk Factors ◽  
Lupus Erythematosus ◽  
Antiphospholipid Antibody ◽  
Future Studies ◽  
Carotid Plaques ◽  
Clinical Procedures ◽  
Glycoprotein I ◽  
Antibody Tests ◽  
Swedish Cohort ◽  
Better Than

Objectives Antiphosphatidylserine/prothrombin complex antibodies (aPS/PT) are risk factors for thrombosis, yet further validation of their clinical relevance in different ethnic groups is required. We investigated the performance of aPS/PT of IgA/G/M isotypes among Sudanese and Swedish systemic lupus erythematosus (SLE) patients. Methods Consecutive SLE patients/matched controls from Sudan (n = 91/102) and Sweden (n = 332/163) were included. All patients fulfilled the 1982 ACR SLE classification criteria. IgA/G/M of aPS/PT, anti-cardiolipin and anti-β2glycoprotein I (anti-β2GPI) were tested in both cohorts, and lupus anticoagulant (LA) also in the Swedish cohort. Clinical antiphospholipid syndrome-related events and atherosclerosis, measured as carotid plaques were assessed for associations. Univariate and multivariate analyses adjusting for cardiovascular risk factors were performed. Results Sudanese SLE patients had higher levels of IgM aPS/PT, but using national cut-offs, the frequency of positivity was similar to Swedish patients for all isotypes. Among Swedish patients, all isotypes of aPS/PT associated with venous thromboembolism (VTE), while only IgA aPS/PT associated with arterial thrombosis (AT). aPS/PT antibodies associated strongly with LA and they were, independently, the best predictor for VTE. Double positivity for aPS/PT and anti-β2GPI associated with higher VTE risk than the conventional triple positivity. Carotid plaques did not associate with any antiphospholipid antibody. Conclusions IgA aPS/PT associated with AT, and the association of IgG/M aPS/PT with VTE outperforms LA and criteria antiphospholipid antibodies in Swedish SLE patients. Furthermore, double positivity for aPS/PT and anti-β2GPI performed better than conventional triple positivity. Future studies need to address if aPS/PT can replace LA, as this would simplify clinical procedures.

Predictive value of persistent versus transient antiphospholipid antibody subtypes for the risk of thrombotic events in pediatric patients with systemic lupus erythematosus

Blood ◽  
2005 ◽  
Vol 106 (13) ◽  
pp. 4152-4158 ◽  
Author(s):  
Christoph Male ◽  
Denise Foulon ◽  
Hugh Hoogendoorn ◽  
Patricia Vegh ◽  
Earl Silverman ◽  
...  
Keyword(s):  
Systemic Lupus Erythematosus ◽  
Lupus Erythematosus ◽  
Predictive Value ◽  
Diagnostic Value ◽  
Anticardiolipin Antibodies ◽  
Antiphospholipid Antibody ◽  
Systemic Lupus ◽  
Glycoprotein I ◽  
Strength Of Association

Study objectives were to determine, in children with systemic lupus erythematosus (SLE), (1) the association of antiphosholipid antibody (APLA) subtypes with thrombotic events (TEs) and (2) the predictive value of persistent versus transient antibodies for TEs. This is a cohort study of 58 SLE children in whom lupus anticoagulants (LAs), anticardiolipin antibodies (ACLAs), anti–β2-glycoprotein-I (anti–β2-GPI), and antiprothrombin (anti-PT) were assessed on at least 2 occasions (more than 3 months apart). Antibodies were classified as persistent (positive on at least 2 occasions) or transient (positive once). Outcomes were symptomatic TEs confirmed by objective radiographic tests identified retrospectively and prospectively. Seven of the 58 patients (12%) had 10 TEs; 5 patients had TEs during prospective follow-up. Persistent LAs showed the strongest association with TEs (P < .001). Persistent ACLAs (P = .003) and anti–β2-GPI (P = .002) were significantly associated with TEs; anti-PT (P = .063) showed a trend. Persistent or transient LAs and anti–β2-GPI showed similar strength of association, while ACLAs and anti-PT were no longer associated with TEs. Positivity for multiple APLA subtypes showed stronger associations with TEs than for individual APLA subtypes because of improved specificity. Lupus anticoagulant is the strongest predictor of the risk of TEs; other APLA subtypes provide no additional diagnostic value. Anticardiolipin antibodies and anti-PT require serial testing because only persistent antibodies are associated with TEs.

scholarly journals Novel Biosensor–Based Analytic Device for the Detection of Anti–Double-Stranded DNA Antibodies

2007 ◽  
Vol 53 (2) ◽  
pp. 334-341 ◽  
Author(s):  
Alexander Buhl ◽  
Jochen H Metzger ◽  
Niels H H Heegaard ◽  
Philipp von Landenberg ◽  
Martin Fleck ◽  
...  
Keyword(s):  
Lupus Erythematosus ◽  
Dependent Manner ◽  
Surface Immobilization ◽  
Surface Binding ◽  
Concentration Dependent Manner ◽  
Spr Biosensor ◽  
Double Stranded Dna ◽  
Healthy Donors ◽  
Biosensor System ◽  
Biosensor Chip

Abstract Background: Patients with systemic lupus erythematosus (SLE) develop a wide variety of serologic manifestations, including double-stranded DNA autoantibodies (anti-dsDNA). The determination of the potentially pathogenic autoantibodies is diagnostically relevant. Methods: We developed a novel surface plasmon resonance (SPR) biosensor chip for studies of dsDNA and anti-dsDNA binding. A synthetic oligonucleotide was coupled to biotinylated human transferrin, hybridized with the complementary antistrand, and ligated with a human recombinant dsDNA fragment 233 bp in length. After surface immobilization of this antigenic construct, diluted sera from SLE patients and healthy donors were analyzed with the resulting SPR biosensor system. Results: This SPR biosensor allowed specific detection of anti-dsDNA. In pilot experiments, sera from SLE patients were distinguished from control sera. We also confirmed the specificity of this biosensor by supplementing anti-dsDNA–positive sera with salmon sperm DNA, which blocked the surface binding of anti-dsDNA in a concentration-dependent manner. Conclusions: An SPR biosensor monitors interactions in real time under homogeneous conditions, providing information about binding kinetics and affinities. Its applicability critically depends on the design of the solid-state surface of the sensor chips. Covalently immobilizing dsDNA as the antigen to the surface in a flow-through cell assured maximal stability for multiple serum injections and regeneration cycles. This technique, which adds a new analytic quality to existing methods, may be beneficial in the diagnosis and clinical monitoring of SLE.

Development of an ELISA for Autoantibodies to Prothrombin Showing their Prevalence in Patients with Lupus Anticoagulants

1995 ◽  
Vol 74 (04) ◽  
pp. 1120-1125 ◽  
Author(s):  
J Arvieux ◽  
L Darnige ◽  
C Caron ◽  
G Reber ◽  
J C Bensa ◽  
...  
Keyword(s):  
Lupus Erythematosus ◽  
Fluid Phase ◽  
Tween 20 ◽  
Antiphospholipid Antibody ◽  
Antiphospholipid Antibody Syndrome ◽  
Drug Induced ◽  
Lupus Anticoagulants ◽  
Glycoprotein I ◽  
Cryptic Epitopes ◽  
Underlying Diseases

SummarySome lupus anticoagulants (LA) have been shown to be directed against phospholipid-bound prothrombin. While developing an ELISA to detect anti-prothrombin autoantibodies in patient serum or plasma, no or very low signal was observed using human prothrombin immobilized on plain polystyrene plates. In contrast, the same LA-positive samples bound specifically to prothrombin coated on γ-irradiated plates, depending on the radiation dose, in the absence of added calcium and phospholipid. Optimization of the assay required the addition of 0.1% Tween 20 to the buffers. Antibody specificity for immobilized prothrombin was ascertained by competition using liposome-bound prothrombin, since fluid-phase prothrombin competed poorly. Seventy-seven of 139 patients (55.4%) with LA related to a variety of underlying diseases possessed anti-prothrombin antibodies (27 IgG, 35 IgM and 15 both isotypes), either isolated or more often associated with anti-(β2 glycoprotein I (β2GPI) antibodies. These included 67-71% of the patients with systemic lupus erythematosus and related disorders, primary antiphospholipid antibody syndrome or drug-induced LA (autoimmune groups), but only 19-20% of those with infection or malignancy (p <0.001). As previously shown for anti-β2GPI antibodies, IgG2 was the predominant IgG subclass reactive with prothrombin. Thus, autoimmune patients with LA have a high incidence of antibodies to β2GPI and prothrombin, the binding of which could similarly require high antigen density and/or exposure of cryptic epitopes resulting from protein interaction with an irradiated (i. e. more anionic) polystyrene surface.

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