scholarly journals Anticardiolipin antibodies recognize beta 2-glycoprotein I structure altered by interacting with an oxygen modified solid phase surface.

1994 ◽  
Vol 179 (2) ◽  
pp. 457-462 ◽  
Author(s):  
E Matsuura ◽  
Y Igarashi ◽  
T Yasuda ◽  
D A Triplett ◽  
T Koike
Keyword(s):  
Photoelectron Spectroscopy ◽  
Gamma Ray ◽  
Solid Phase ◽  
Anticardiolipin Antibodies ◽  
Enzyme Linked Immunosorbent Assay ◽  
Polystyrene Surface ◽  
Glycoprotein I ◽  
Latex Beads ◽  
Beta 2 ◽  
Phase Surface

Anticardiolipin antibodies (aCL) derived from the sera of individuals exhibiting the antiphospholipid syndrome (APS) directly bind to beta 2-glycoprotein I (beta 2-GPI), which is adsorbed to an oxidized polystyrene surface. Oxygen atoms were introduced on a polystyrene surface by irradiation with electron or gamma-ray radiation. X-ray photoelectron spectroscopy revealed the irradiated surfaces were oxidized to generate C-O and C = O moieties. aCL derived from either APS patients or (NZW x BXSB)F1 mice bound to beta 2-GPI coated on the irradiated plates, depending on the radiation dose. Antibody binding to beta 2-GPI on the irradiated plates was competitively inhibited by simultaneous addition of cardiolipin (CL)-coated latex beads mixed together with beta 2-GPI but were unaffected by addition of excess beta 2-GPI, CL micelles, or CL-coated latex beads alone. There was a high correlation between binding values of aCL in sera from 40 APS patients obtained by the anti-beta 2-GPI enzyme-linked immunosorbent assay (ELISA) using the irradiated plates and those by the beta 2-GPI-dependent aCL ELISA. Therefore, aCL have specificity for an epitope on beta 2-GPI. This epitope is expressed by a conformational change occurring when beta 2-GPI interacts with an oxygen-substituted solid phase surface.

The Interaction of β2 Glycoprotein-I and Heparin and Its Effect on β2 Glycoprotein-I Antiphospholipid Antibody Cofactor Function in Plasma

1994 ◽  
Vol 72 (04) ◽  
pp. 578-581 ◽  
Author(s):  
T McNally ◽  
S E Cotterell ◽  
I J Mackie ◽  
D A Isenberg ◽  
S J Machin
Keyword(s):  
Solid Phase ◽  
Pharmaceutical Preparations ◽  
Enzyme Linked Immunosorbent Assay ◽  
Antiphospholipid Antibody ◽  
Biological Functions ◽  
Dermatan Sulphate ◽  
Glycoprotein I ◽  
Crossed Immunoelectrophoresis ◽  
Calcium Heparin ◽  
Cofactor Activity

Summaryβ2 glycoprotein-I (β2GPI), a cofactor for antiphospholipid antibody (aPA) binding, binds to many anionic macromolecules including heparin. The nature of this interaction with heparin is not well understood and its effect on the purported biological functions of β2GPI is unknown.We have examined the interactions of dermatan sulphate (DS) and different pharmaceutical preparations of heparin with β2GPI by crossed immunoelectrophoresis (CIE) and investigated the effect of these agents on plasma levels of p2GPI antigen (β2GPI: Ag) by a standardised enzyme linked immunosorbent assay (ELISA). P2GPI aPA cofactor activity (β2GPI:Cof) was also measured using a modified solid phase an-ti-phosphatidylserine (aPS) ELISA. CIE results confirmed a heparin-β2GPI interaction with unfractionated (UF) heparin. β2GPI:Ag levels were unaffected by any of the preparations investigated. There were no significant differences in β2GPI:Cof activities of the samples containing LMW heparins or DS but levels of β2GPI:Cof were increased in samples containing UF sodium and calcium heparin preparations (0.5 IU/ml Monoparin, p <0.05, and 10 IU/ml Liquemin and Calcipa-rine, p <0.05).

scholarly journals Beta 2-glycoprotein I is a requirement for anticardiolipin antibodies binding to activated platelets: differences with lupus anticoagulants

Blood ◽  
1993 ◽  
Vol 81 (5) ◽  
pp. 1255-1262 ◽  
Author(s):  
W Shi ◽  
BH Chong ◽  
CN Chesterman
Keyword(s):  
Cross Reactivity ◽  
Anticardiolipin Antibodies ◽  
Ion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Glycoprotein I ◽  
Activated Platelets ◽  
Major Interest ◽  
Thrombin Activation ◽  
Beta 2

Abstract Antiphospholipid (aPL) antibodies are of major interest not only because the lupus anticoagulant (LA) causes an inhibition of in vitro blood coagulation, but also because the presence of aPL antibodies confers a risk of thrombosis. The inhibition of in vitro phospholipid- dependent coagulation (LA) is thought to be caused by the binding of LA to procoagulant phospholipid surfaces, thus impeding the clotting process. Another class of aPL antibodies are those originally described to be directed against negatively charged phospholipids, in particular cardiolipin (ACA). ACA are usually directed against a complex antigen consisting of negatively charged phospholipid and a plasma protein, beta 2-glycoprotein I (beta 2-GPI). Further, there is antibody heterogeneity even within individual patients so that ACA and LA are separable using physicochemical techniques such as ion exchange chromatography and chromatofocusing. Using such techniques we have enriched Ig fractions for LA and ACA from two patient plasmas. The majority of Ig with LA activity had a pI of 7.2 to 7.3 whereas ACA had a pI of 5.0 to 5.2. Using these enriched fractions labeled with [125I]- iodine we have shown that LA binds to platelets in a specific and saturable manner. Binding is dependent on thrombin activation. [125I]- ACA behaves differently. Like LA, binding is specific and dependent on thrombin activation but in this case requires the presence of beta 2- GPI. ACA, in the presence of beta 2-GPI, competes for binding with LA suggesting the same or contiguous site. There is no cross-reactivity of these antibodies with GPIIb/IIIa and the most likely binding site is phospholipid. In neither case does LA nor ACA have an effect on thrombin-induced release of serotonin or beta-thromboglobulin nor do they affect platelet aggregation induced by a number of agonists. This antibody binding may play an etiological role in thrombocytopenia associated with aPL, but does not explain thrombosis on the basis of hyperaggregability or increased platelet release.

scholarly journals Activation of human platelets by the rabbit anticardiolipin antibodies

Blood ◽  
1992 ◽  
Vol 80 (12) ◽  
pp. 3135-3143 ◽  
Author(s):  
YL Lin ◽  
CT Wang
Keyword(s):  
Solid Phase ◽  
Shape Change ◽  
Human Platelets ◽  
Anticardiolipin Antibodies ◽  
Ion Concentration ◽  
Enzyme Linked Immunosorbent Assay ◽  
Free Calcium ◽  
Dependent Manner ◽  
Platelet Response ◽  
Inhibition Studies

Abstract Affinity purified anticardiolipin antibodies (ACLA) raised in rabbits showed cross-reactivities with various negatively charged phospholipids as shown by both the solid phase enzyme-linked immunosorbent assay (ELISA) and inhibition studies. In ELISA, ACLA showed strong cross-reactivity to both sphingomyelin (SM) and phosphatidylethanolamine (PE), but the inhibition studies showed that ACLA failed to bind the aqueous suspensions of SM, PE, and PE/PC (1:1). ACLA bound to resting gel-filtered human platelets (GFP) as shown by both inhibition study and flow cytofluorometric analysis. Western blotting procedure showed that ACLA strongly cross-reacted to an 80-Kd plasma membrane protein. ACLA activated platelet response in a concentration-dependent manner. At less than 10 micrograms/mL, ACLA induced both platelet shape change to spiculate irregular forms as shown by scanning electron microscopy and the phosphorylation of 20-Kd protein. ACLA at more than 10 micrograms/mL caused platelet aggregation and secretion. The aggregation was inhibited by EDTA; aspirin; antimycin A plus 2-deoxyglucose; PGE1; and the F(ab')2 fragment of ACLA. It was not inhibited by monoclonal antibody to Fc receptor (MoAb FcR2). The biochemical events of ACLA-induced platelet response involved the elevation of (1) thromboxane A2 formation, (2) cytosolic free calcium ion concentration ([Ca2+]i), and (3) 47-Kd protein phosphorylation. In addition, the subaggregatory concentration of ACLA showed synergistic platelet activation with that concentration of thrombin, collagen, and epinephrine. The study showed the mechanism involved in ACLA-induced platelet responses.

Antiphospholipid antibodies in patients with purported ‘chronic Lyme disease’

Lupus ◽  
2011 ◽  
Vol 20 (13) ◽  
pp. 1372-1377 ◽  
Author(s):  
TP Greco ◽  
AM Conti-Kelly ◽  
TP Greco
Keyword(s):  
Lyme Disease ◽  
Western Blot ◽  
Antiphospholipid Antibodies ◽  
Lupus Anticoagulant ◽  
Anticardiolipin Antibodies ◽  
Enzyme Linked Immunosorbent Assay ◽  
Antiphospholipid Antibody ◽  
Chronic Lyme Disease ◽  
Beta 2

Background: Antiphospholipid antibody (aPL) positive patients and patients with purported chronic Lyme disease (‘CLD’) share many clinical features. After identifying significant aPL in sera of several index patients with ‘CLD’, we performed aPL tests on all patients referred inwhom ‘CLD’ was suspected, diagnosed or treated. Methods: All patients with suspected, diagnosed or treated ‘CLD’ and reportedly ‘positive’ Lyme assays were studied. aPL testing included anticardiolipin antibodies (aCL), anti-beta-2-glycoprotein-1 antibodies (anti-β2GP1) and lupus anticoagulant (LAC). Patients were classified into four newly described categories of CLD and data was analyzed. Results: One hundred and six patients were evaluated, of whom 82% had neurologic symptoms and 51% rheumatologic symptoms. Eighty-eight of 106 (83%) patients had positive Lyme serologies (enzyme-linked immunosorbent assay [ELISA] 62/106, 58.4%; western blot [WB] 64/106, 60%), while 18/106 (16.9%) were negative or equivocal. aPL was found in all ‘CLD’ categories. aCL and/or anti-β2GP1 were positive in 85/106 (80%), with aCL present in 69/106 (65%) and anti-β2GP1 present in 69/106 (65%). For all assays, IgM isotypes predominated: WB 55/64 (85%), aCL 63/69 (91%), anti-β2GP1 52/69 (75%), aCL and/or anti-β2GP1 74/85 (87%). Anti-β2GP1 assays occurred in higher titer than aCL: 36/69 (52%) versus 63/69 (91%), p<0.001. Seventeen patients had aPL-related events. Only 12/106 (11.3%) had true post-Lyme syndromes (PLS), category IV, or late Lyme disease (LLD). Most patients had been treated for Lyme: 82/106 (79%). Conclusion: aPL occurs frequently in patients with ‘CLD’. IgM anti-β2GP1, IgM aCL and IgM WB were frequently found. Documented PLS or LLD was uncommon. The role of aPL in patients with ‘CLD’ needs further investigation. Lupus (2011) 20, 1372–1377.

scholarly journals Microheterogeneity of beta-2 glycoprotein I: implications for binding to anionic phospholipids

1999 ◽  
Vol 340 (1) ◽  
pp. 59-67 ◽  
Author(s):  
Timothy A. BRIGHTON ◽  
Yan-Ping DAI ◽  
Philip J. HOGG ◽  
Colin N. CHESTERMAN
Keyword(s):  
Dissociation Constants ◽  
Solid Phase ◽  
Physiological Role ◽  
Unilamellar Vesicles ◽  
Anionic Phospholipid ◽  
Binding Characteristics ◽  
Phospholipid Binding ◽  
Anionic Phospholipids ◽  
Glycoprotein I ◽  
Beta 2

Considerable interest is currently focused on the interactions of beta-2 glycoprotein I (β2GPI) and anti-phospholipid antibodies with anionic phospholipids in an attempt to understand the association between these antibodies and clinical diseases such as thrombosis. The interactions of β2GPI and anionic phospholipids have only been characterized partially, and the physiological role of this glycoprotein remains uncertain. In this study we have explored in detail the physical and phospholipid-binding characteristics of a number of β2GPI preparations. We have found (i) that perchloric acid-purification methods are damaging to β2GPI during purification, (ii) that the dissociation constants of the various preparations for phosphatidylserine vary between 0.1-2 μM and are considerably weaker than previously reported, (iii) that considerable differences in affinity of the various β2GPI preparations for anionic phospholipids are obtained when comparing anionic phospholipids immobilized to a solid-phase versus phospholipid assembled in unilamellar vesicles, (iv) that the integrity of the fifth domain of β2GPI is important for binding immobilized anionic phospholipid but not especially important in binding vesicular anionic phospholipid, and (v) that β2GPI preparations with differing isoelectric species content bind anionic phospholipids differently, suggesting that varying glycosylation and/or protein polymorphisms impact upon phospholipid binding. These results highlight the importance of assessing the determinants of the interaction of β2GPI with anionic phospholipids assembled in unilamellar vesicles.

scholarly journals Laboratory methods to detect antiphospholipid antibodies

Hematology ◽  
2014 ◽  
Vol 2014 (1) ◽  
pp. 321-328 ◽  
Author(s):  
Steven A. Krilis ◽  
Bill Giannakopoulos
Keyword(s):  
Clinical Significance ◽  
Antiphospholipid Antibodies ◽  
Lupus Anticoagulant ◽  
Solid Phase ◽  
Evidence Based ◽  
Diagnostic Utility ◽  
Laboratory Methods ◽  
Detailed Review ◽  
Glycoprotein I ◽  
Beta 2

Abstract This chapter reviews several important themes pertaining to the antiphospholipid syndrome (APS), including a description of the clinical features, a discussion of the main autoantigen, beta 2-glycoprotein I (β2GPI), and insights into the characteristics of the pathogenic anti-β2GPI autoantibodies. Evidence-based considerations for when to test for APS are explored, along with the clinical significance of patients testing positive on multiple APS assays, so-called triple positivity. A detailed review of recently published laboratory guidelines for the detection of lupus anticoagulant and the solid-phase anticardiolipin and anti-β2GPI ELISAs is undertaken. Finally, a brief review of nonclassification criteria laboratory assays with potential future diagnostic utility is presented.

Antiprothrombin antibody: why do we need more assays?

Lupus ◽  
2010 ◽  
Vol 19 (4) ◽  
pp. 436-439 ◽  
Author(s):  
T. Atsumi ◽  
T. Koike
Keyword(s):  
Sensitivity And Specificity ◽  
Antiphospholipid Syndrome ◽  
Lupus Anticoagulant ◽  
Laboratory Tests ◽  
Diagnostic Value ◽  
Anticardiolipin Antibodies ◽  
Confirmatory Test ◽  
Enzyme Linked Immunosorbent Assay ◽  
Glycoprotein I

Anticardiolipin antibodies (aCL), anti-β2-glycoprotein I (β2GPI) antibodies and lupus anticoagulant (LA) are the only laboratory tests considered within the revised criteria for the classification of the antiphospholipid syndrome (APS). Recently, the significance to assay the antibodies against phosphatidylserine—prothrombin complex (aPS/PT) has been discussed, and these antibodies, rather than antibodies against prothrombin alone, are closely associated with APS and LA. The sensitivity and specificity of aPS/PT for the diagnosis of APS were assessed in a population of patients with a variety of autoimmune disorders. The aCL and aPS/PT have similar diagnostic value for APS, and most of APS patients with aPS/PT had positive LA. Therefore, aPS/PT should be further explored, not only for research purposes, but also as a candidate for one of the enzyme-linked immunosorbent assay (ELISA)-based confirmatory test for APS associated LA.

scholarly journals COVID-19 and Antiphospholipid Antibodies: Time for a Reality Check?

2021 ◽  
Author(s):  
Emmanuel J. Favaloro ◽  
Brandon Michael Henry ◽  
Giuseppe Lippi
Keyword(s):  
Antiphospholipid Antibodies ◽  
Solid Phase ◽  
High Titer ◽  
Severe Form ◽  
Anticardiolipin Antibodies ◽  
Antiphospholipid Antibody ◽  
Antiphospholipid Antibody Syndrome ◽  
Glycoprotein I ◽  
Autoimmune Conditions ◽  
Antiprothrombin Antibodies

AbstractAntiphospholipid antibodies (aPL) comprise a panel of autoantibodies that reflect a potential prothrombotic risk in several autoimmune conditions, most notably antiphospholipid (antibody) syndrome (APS). aPL can be divided into those that form part of the laboratory criteria for APS, namely, lupus anticoagulant (LA), as well as anticardiolipin antibodies (aCL) and anti-β2-glycoprotein I antibodies (aβ2GPI) of the immunoglobulin G and M classes, and those that form a group considered as “noncriteria antibodies.” The noncriteria antibodies include, for example, antiphosphatidylserine antibodies (aPS), antiprothrombin antibodies (aPT), and antiphosphatidylserine/prothrombin complex antibodies (aPS/PT). COVID-19 (coronavirus disease 2019) represents a prothrombotic disorder, and there have been several reports of various aPL being present in COVID-19 patients. There have also been similarities drawn between some of the pathophysiological features of COVID-19 and APS, in particular, the most severe form, catastrophic APS (CAPS). In this review, we critically appraise the literature on aPL and COVID-19. This is a companion piece to a separate review focused on LA. In the current review, we primarily concentrate on the so-called solid phase identifiable aPL, such as aCL and aβ2GPI, but also reflect on noncriteria aPL. We conclude that aPL positivity may be a feature of COVID-19, at least in some patients, but in general, identified “solid-phase” aPL are of low titer and not able to be well-linked to the thrombotic aspects of COVID-19. Also, most publications did not assess for aPL persistence, and where persistence was checked, the findings appeared to represent transient aPL. Importantly, high-titer aPL or multiple aPL positivity (including double, triple) were in the minority of COVID-19 presentations, and thus discount any widespread presence of APS, including the most severe form CAPS, in COVID-19 patients.

scholarly journals Beta 2-glycoprotein I is a requirement for anticardiolipin antibodies binding to activated platelets: differences with lupus anticoagulants

Blood ◽  
1993 ◽  
Vol 81 (5) ◽  
pp. 1255-1262 ◽  
Author(s):  
W Shi ◽  
BH Chong ◽  
CN Chesterman
Keyword(s):  
Cross Reactivity ◽  
Anticardiolipin Antibodies ◽  
Ion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Glycoprotein I ◽  
Activated Platelets ◽  
Major Interest ◽  
Thrombin Activation ◽  
Beta 2

Antiphospholipid (aPL) antibodies are of major interest not only because the lupus anticoagulant (LA) causes an inhibition of in vitro blood coagulation, but also because the presence of aPL antibodies confers a risk of thrombosis. The inhibition of in vitro phospholipid- dependent coagulation (LA) is thought to be caused by the binding of LA to procoagulant phospholipid surfaces, thus impeding the clotting process. Another class of aPL antibodies are those originally described to be directed against negatively charged phospholipids, in particular cardiolipin (ACA). ACA are usually directed against a complex antigen consisting of negatively charged phospholipid and a plasma protein, beta 2-glycoprotein I (beta 2-GPI). Further, there is antibody heterogeneity even within individual patients so that ACA and LA are separable using physicochemical techniques such as ion exchange chromatography and chromatofocusing. Using such techniques we have enriched Ig fractions for LA and ACA from two patient plasmas. The majority of Ig with LA activity had a pI of 7.2 to 7.3 whereas ACA had a pI of 5.0 to 5.2. Using these enriched fractions labeled with [125I]- iodine we have shown that LA binds to platelets in a specific and saturable manner. Binding is dependent on thrombin activation. [125I]- ACA behaves differently. Like LA, binding is specific and dependent on thrombin activation but in this case requires the presence of beta 2- GPI. ACA, in the presence of beta 2-GPI, competes for binding with LA suggesting the same or contiguous site. There is no cross-reactivity of these antibodies with GPIIb/IIIa and the most likely binding site is phospholipid. In neither case does LA nor ACA have an effect on thrombin-induced release of serotonin or beta-thromboglobulin nor do they affect platelet aggregation induced by a number of agonists. This antibody binding may play an etiological role in thrombocytopenia associated with aPL, but does not explain thrombosis on the basis of hyperaggregability or increased platelet release.

scholarly journals Activation of human platelets by the rabbit anticardiolipin antibodies

Blood ◽  
1992 ◽  
Vol 80 (12) ◽  
pp. 3135-3143 ◽  
Author(s):  
YL Lin ◽  
CT Wang
Keyword(s):  
Solid Phase ◽  
Shape Change ◽  
Human Platelets ◽  
Anticardiolipin Antibodies ◽  
Ion Concentration ◽  
Enzyme Linked Immunosorbent Assay ◽  
Free Calcium ◽  
Dependent Manner ◽  
Platelet Response ◽  
Inhibition Studies

Affinity purified anticardiolipin antibodies (ACLA) raised in rabbits showed cross-reactivities with various negatively charged phospholipids as shown by both the solid phase enzyme-linked immunosorbent assay (ELISA) and inhibition studies. In ELISA, ACLA showed strong cross-reactivity to both sphingomyelin (SM) and phosphatidylethanolamine (PE), but the inhibition studies showed that ACLA failed to bind the aqueous suspensions of SM, PE, and PE/PC (1:1). ACLA bound to resting gel-filtered human platelets (GFP) as shown by both inhibition study and flow cytofluorometric analysis. Western blotting procedure showed that ACLA strongly cross-reacted to an 80-Kd plasma membrane protein. ACLA activated platelet response in a concentration-dependent manner. At less than 10 micrograms/mL, ACLA induced both platelet shape change to spiculate irregular forms as shown by scanning electron microscopy and the phosphorylation of 20-Kd protein. ACLA at more than 10 micrograms/mL caused platelet aggregation and secretion. The aggregation was inhibited by EDTA; aspirin; antimycin A plus 2-deoxyglucose; PGE1; and the F(ab')2 fragment of ACLA. It was not inhibited by monoclonal antibody to Fc receptor (MoAb FcR2). The biochemical events of ACLA-induced platelet response involved the elevation of (1) thromboxane A2 formation, (2) cytosolic free calcium ion concentration ([Ca2+]i), and (3) 47-Kd protein phosphorylation. In addition, the subaggregatory concentration of ACLA showed synergistic platelet activation with that concentration of thrombin, collagen, and epinephrine. The study showed the mechanism involved in ACLA-induced platelet responses.

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