Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P02749 (beta2-glycoprotein I)
 836 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

aPL antibodies are a wide and heterogeneous family of autoantibodies, formerly believed to be directed at anionic phospholipids. In recent years they have been shown to be directed at plasma proteins bound to suitable (phospholipid) anionic surface: beta 2-GPI and prothrombin are the best known and characterized antigens, which are recognized by aCL antibodies and most Lupus Anticoagulants, respectively. The presence of these antibodies has been associated with arterial and venous thrombosis, recurrent miscarriages and thrombocytopenia in the so-called "Antiphospholipid Syndrome". Retrospective and "cross-sectional" studies have established the role of aCL antibodies and Lupus Anticoagulants as risk factors for both venous and arterial thrombosis, the most common clinical manifestations of APS. Prospective studies performed in different patients' populations have validated the association between aCL antibodies and Lupus Anticoagulants with venous and, possibly, arterial thrombosis. Along with the concept of the heterogenity of aPL antibodies there is the observation that among Lupus Anticoagulants aCL-type A, but not LA antibodies, appear to represent a risk factor for thrombosis. However, informations on the predictive value of the various laboratory tests with respect to thrombosis are still rather limited. It is, therefore, necessary to continue the development and standardization of assays that selectively identify aPL antibodies associated with an increased risk of thrombosis, in order to help the clinicians to establish the most appropriate therapeutic strategies for the prevention of the thromboembolic complication of APS.
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PMID:Antiphospholipid antibodies: predictive value of laboratory tests. 919 31

Antiphospholipid antibodies (aPL) have been associated with various neurological manifestations, but the underlying mechanism has not been elucidated. We assessed mice with induced experimental antiphospholipid syndrome (APS) for neurological and behavioral changes. After immunization with monoclonal human anticardiolipin antibody (H-3), female BALB/c mice developed elevated levels of circulating anti-negatively charged phospholipids (aPL), anti-beta2-glycoprotein I (abeta2GPI), and anti-endothelial cell antibodies (AECA), along with clinical manifestations of APS like thrombocytopenia and fetus resorption. APS mice were impaired neurologically and performed several reflexes less accurately compared to the controls, including placing reflex (P < 0.05), postural reflex (P < 0.05), and grip test (P = 0.05). The APS mice also exhibited hyperactive behavior in an open field, which tests spatial behavior (P < 0.03), and displayed impaired motor coordination on a rotating bar. aPL in combination with abeta2GPI and AECA is probably involved in the neurological and behavioral defects shown in mice with experimental APS.
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PMID:Neurological dysfunction and hyperactive behavior associated with antiphospholipid antibodies. A mouse model. 923 9

Male (NZW x BXSB)F1 (W/BF1) mice develop a systemic lupus-like syndrome characterized by thrombocytopenia, coronary vascular disease, nephritis, and anticardiolipin antibodies. Three stable hybridoma cell lines secreting monoclonal anticardiolipin antibodies were developed from these mice by fusing their splenic lymphocytes with nonsecreting myeloma cell line, NS-1. Monoclonal antibody A1.17 reacted with cardiolipin in a beta2-Glycoprotein I-dependent manner. The epitope for this antibody consisted of beta2-glycoprotein I bound to cardiolipin or immobilized on plastic plates. Other anionic phospholipid-binding proteins, such as prothrombin or annexin V, had no significant effect in the reactivity of these antibodies. The specificity is similar to the autoimmune anticardiolipin antibodies described in patients with systemic lupus erythematosus and other infectious diseases. In contrast, monoclonal antibodies A1.72 and A1.84 reacted with cardiolipin in the absence of beta2-glycoprotein I. Beta2-glycoprotein I, either in the fluid phase or bound to cardiolipin, inhibited the binding of these antibodies. The specificity of the latter two antibodies was similar to that described in patients with syphilis and allied disorders. Both types of antibodies had lupus anticoagulant properties. Thus lupus-prone male (NZW x BXSB)F1 (W/BF1) mice develop both beta2-glycoprotein I-dependent and beta2-glycoprotein I-independent anticardiolipin antibodies.
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PMID:Characterization of beta2-glycoprotein I-dependent and -independent "antiphospholipid" antibodies from lupus-prone NZW/BXSB F1 hybrid male mice. 932 49

Antiphospholipid antibodies are a wide ranging, heterogeneous family of autoantibodies, formerly believed to be directed to anionic phospholipids. Recent research, however, has confirmed that they are directed to plasma proteins bound to suitable (phospholipid) anionic surfaces. The most well-known and best characterized antigens are beta 2-glycoprotein I, recognized by anticardiolipin antibodies, and prothrombin, recognized by most lupus anticoagulants. Lupus anticoagulants are generally identified on the basis of their capacity to prolong the phospholipid-dependent coagulation tests. Two types of lupus anticoagulants, anticardiolipin-type A, and antiprothrombin antibodies, whose presence is associated with different coagulation profiles, have been identified. Anticardiolipin-type A and antiprothrombin antibodies may be detected also by specific immunoassays. The capacity of several methodologies to detect antiphospholipid antibodies reflects chiefly their immunological and functional heterogeneity. Since most of the laboratory methods have not yet been standardized, the results of studies on the clinical relevance of antiphospholipid antibodies must be analyzed with caution. The association between antiphospholipid antibodies with peculiar clinical manifestations such as venous and arterial thrombosis, recurrent miscarriage, and thrombocytopenia, characterizes the so-called "antiphospholipid syndrome". Retrospective and cross-sectional studies have confirmed the role of anticardiolipin antibodies and lupus anticoagulants as risk factors for both venous and arterial thrombosis, the most common clinical manifestations of the antiphospholipid syndrome. Prospective studies performed in different patient populations have confirmed the association between anticardiolipin antibodies and lupus anticoagulants with venous, and possibly, arterial thrombosis, although information on the predictive value of the various laboratory tests with respect to thrombosis is still limited. It is hoped that the development and standardization of assays that selectively identify antiphospholipid antibodies associated with increased risk of thrombosis will lead to therapeutic strategies able to prevent thromboembolic complications of the antiphospholipid syndrome.
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PMID:[Clinical significance and predictive value of laboratory tests in thrombosis associated with antiphospolipid antibodies]. 933 16

During late seventies it became apparent that the appearance of antiphospholipid antibodies is associated with thromboembolic manifestations, such as cerebral or myocardial infarction, pulmonary thromboembolism, deep vein thrombosis, intrauterine fetal losses and thrombocytopenia. The term antiphospholipid syndrome has been used to define this set of pathologic features. Recognition of this syndrome has spread worldwide as its clinical implications have become appreciated. Recent studies showed that cofactor, beta 2-glycoprotein I (beta 2-GPI) is required for binding of anticardiolipin antibodies (aCL) raised in the patients with SLE and related other autoimmune disorders. However, this finding has generated considerable controversy. Four different hypotheses have been proposed to explain the specificity of aCL: (1) CL is directly recognized by aCL; (2) the beta 2-GPI-CL complex is the structure recognized by aCL; (3) the beta 2-GPI is the actual target antigen for aCL but is cryptic in the absence of CL; and (4) the actual epitope for aCL appears on the native structure of beta 2-GPI. We showed that aCL bound to beta 2-GPI interacting with poly-oxygenated plates and in the absence of CL, an interaction which depends on introduction of oxygen atoms on the polystyrene surface. We also showed that the beta 2-GPI bound to CL via a particular region on the fifth domain, namely C281KNKEKKC288, and the tertiary structure of the region is involved in binding to phospholipid. Several mechanisms to explain the vascular injury and thrombosis associated with aCL have been proposed, primarily based on their phospholipid reactivity to activated platelets. Whether aCL-through binding to complex of beta 2-GPI and negatively charged phospholipid in the phospholipid-dependent coagulation reactions of hemostasis contribute to the increased risk of thrombosis in patients with aCL is an important question in need of an answer. We have demonstrated the possibility that not only activated platelets but also oxidized lipoproteins, e.g., low-density lipoprotein (LDL), may be thrombogenic targets of aCL which recognize the altered beta 2-GPI structure.
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PMID:[Autoantibodies and thrombosis]. 936 65

We report a 40-year-old Japanese woman with antiphospholipid antibody syndrome (APS) associated with myasthenia gravis (MG). She had a history of miscarriage at the age of 27 followed by pulmonary embolism 3 weeks later. At the age of 40, she developed diplopia, bilateral ptosis and easy fatigability. Serum anti-acetylcholine receptor antibody and tensilon test were positive. She was diagnosed as having MG. The laboratory test revealed mild thrombocytopenia, prolonged activated partial thromboplastin time (aPTT) and positive findings for both beta 2-glycoprotein I-dependent anticardiolipin antibody and lupus anticoagulant. She fulfilled the diagnostic criteria of APS, but did not the criteria proposed by American Rheumatism Association for SLE. An extended total thymectomy was performed after administration of oral prednisolone and low-dose aspirin. This is a patient who had APS associated with MGs: both are known to result from autoimmune abnormality. The clinical and laboratory manifestations of APS were ameliorated after removal of the thymus, suggesting that thymectomy alleviates APS symptoms.
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PMID:[A case of antiphospholipid syndrome associated with myasthenia gravis]. 939 64

The aim of this study was to characterize the antigen specificity and to evaluate the diagnostic and prognostic value of anti-mitochondrial M5 type antibodies (AMA M5). Fifty-eight patients selected on the basis of their AMA M5 positivity were investigated in relationship to their clinical and serological profile. Cross-absorption studies, Western blotting and immunoprecipitation analysis were carried out for AMA M5 antigen specificity characterization. Most patients had a diagnosis of systemic lupus erythematosus (SLE) (65.5%) or of primary anti-phospholipid syndrome (PAPS) (24%); all the patients were positive for IgG or IgM anti-cardiolipin (anti-CL) antibodies and 49% of them also displayed lupus anticoagulant (LA) activity. Anti-beta2-glycoprotein I (beta2-GPI) IgG were detectable in 30/38 sera (78.9%) and IgM in 34/38 (89.4%). While anti-CL and anti-beta2-GPI IgG antibodies were significantly associated with history of thrombosis and fetal loss, AMA M5 displayed a statistical association only for thrombocytopenia and recurrent fetal loss. Absorption with human beta2-GPI both in free solution or in solid phase as well as with CL liposomes or CL/beta2-GPI liposome complexes did not affect AMA M5 fluorescence. While AMA M5 activity is absorbed by whole mitochondrial preparations, no specific reactivities against several human, bovine and rat mitochondrial proteins could be detected in Western blotting and immunoprecipitation studies. AMA M5 appear to be detectable in both primary and secondary APS, displaying a strong association with the presence of thrombocytopenia and fetal loss. Although strictly related to anti-phospholipid antibodies, AMA M5, anti-CL and anti-beta2-GPI antibodies represent distinct serological markers of the APS.
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PMID:Anti-mitochondrial M5 type antibody represents one of the serological markers for anti-phospholipid syndrome distinct from anti-cardiolipin and anti-beta2-glycoprotein I antibodies. 956 3

Antibodies to beta 2-glycoprotein in the serum of patients with antiphospholipid syndrome (APS) were found by many investigators, but their results appeared contraversional. We studied clinical significance of antibodies to beta 2-glycoprotein I (anti-beta 2-GPI) in patients with SLE. 69 patients with verified SLE were examined for lupus anticoagulant (LA), antibodies to cardiolipin (aCL) and anti-beta 2-GPI. 44(65%), 46(67%), 49(71%), 19(28%), 16(23%) patients were positive for LA, IgG-aCL, IgM-aCL, IgG-anti-beta 2-GPI and IgM-anti-beta 2-GPI, respectively. Hyperproduction of IgG-anti-beta 2-GPI correlated with APS development as a whole, its separate clinical symptoms (venous and arterial thromboembolism, obstetric pathology and thrombocytopenia) and some comcomitant clinical signs (trophic crural ulcer, hemolytic anemia, valvular heart disorders). Moreover, an increase in concentration of IgM-anti-beta 2-GPI was associated with habitual abortion. Both isotypes of anti-beta 2-GPI occurred more frequently in the sera positive by LA and aCL. It is interesting that we discovered IgG-anti-beta 2-GPI more often in early than late postthrombolytic period. Thus, anti-2b2-GPI is a new serological marker of APS. Its detection is clinically important for upgrading diagnosis of APS.
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PMID:[Antibodies to beta2-glycoprotein I in systemic lupus erythematosus: new laboratory marker of antiphospholipid syndrome]. 957 46

Antiphospholipid antibodies have been demonstrated in chronic hepatitis C, but their clinical and pathogenetic significance remains elusive. We prospectively studied 115 patients (85 men, mean age 36.9 years) with chronic hepatitis C without cirrhosis and treated by alpha-interferon (alpha-IFN). Antiphospholipid determinations comprised anticardiolipin (ACA), anti-beta2-glycoprotein I and anti-prothrombin antibodies of the IgG and IgM classes. At entry, 24 patients (21%) were found to possess low to moderate ACA levels (18 IgG, two IgM and four both isotypes) compared with only 4/115 age- and sex-matched control subjects (3.5% P=0.001). ACA positivity rate increased to 31% (P=0.01) after a 6-month course of alpha-IFN treatment. In contrast, the prevalence of anti-beta2-glycoprotein I and anti-prothrombin antibodies was not significantly different from controls at either time point. The presence of ACA correlated with that of antinuclear antibodies (P=0.0002), but was not associated with parameters such as histological activity, viral burden and response to alpha-IFN, nor with a history of thrombosis or pregnancy loss. However, a non-significant trend of higher incidence of mild thrombocytopenia among ACA-positive patients was observed. We conclude that low-titre ACA positivity is a common finding in patients with chronic hepatitis C, especially following alpha-IFN treatment, but does not select a category with different clinical features. These data are in keeping with the absence of associated anti-beta2GPI and anti-prothrombin antibodies, and do not support a role for HCV infection in the pathogenesis of the antiphospholipid syndrome.
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PMID:Prevalence and significance of anticardiolipin, anti-beta2 glycoprotein I and anti-prothrombin antibodies in chronic hepatitis C. 963 88

"Antiphospholipid" autoantibodies are associated with arterial and venous thrombosis, recurrent fetal loss, and thrombocytopenia. At present, the best-characterized antigenic target for these autoantibodies (or Abs) is the phospholipid-binding protein beta2-glycoprotein I (beta2GPI). These Abs bind beta2GPI only in the presence of negatively charged phospholipids or microtiter polystyrene plates that have been specially treated to give the surface a negative charge. To determine whether the binding of these Abs to beta2GPI on negatively charged surfaces is dependent on increased density or neo-epitopes formed as a consequence of a conformational change on beta2GPI, we generated mutants of beta2GPI by site-directed mutagenesis and assessed the binding characteristics of anti-beta2GPI Abs to these mutants. Our results demonstrate that mutant F307*, which spontaneously forms significant dimerization, is bound best by all the anti-beta2GPI Abs in an anti-beta2GPI ELISA using irradiated polystyrene microtiter plates. In addition, these Abs bound mutant F307* coated onto standard polystyrene microtiter wells in the absence of phospholipid, whereas there was minimal binding with wild-type and mutant F307*/C288A, which formed minimal dimerization. Affinity-purified anti-beta2GPI Abs from patients with the antiphospholipid syndrome demonstrated significantly higher binding affinity for mutant F307* in fluid phase than for wild-type or mutant F307*/C288A of beta2GPI. These results demonstrate that autoantibody binding to beta2GPI is intrinsically of low affinity and that the binding is dependent on the density of the Ag and not on neo-epitope formation.
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PMID:Anti-beta 2-glycoprotein I autoantibodies from patients with the "antiphospholipid" syndrome bind to beta 2-glycoprotein I with low affinity: dimerization of beta 2-glycoprotein I induces a significant increase in anti-beta 2-glycoprotein I antibody affinity. 971 77


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