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Query: UNIPROT:P02749 (beta2-glycoprotein I)
 836 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The authors have determined the prevalence of antibodies of cofactor dependent anticardiolipin and beta 2-glycoprotein I and lupus anticoagulant and the frequency of false positive VDRL test in systemic lupus erythematosus. The aim of this retrospective study was to assess the presence of these antibodies and symptoms of antiphospholipid syndrome. The serum samples were examined by modified ELISA method for detecting of cofactor dependent anticardiolipin. The antibodies to beta 2-glycoprotein I were examined by ELISA. The lupus anticoagulant and VDRL test were performed by routine laboratory method. The authors have found that 19 of 58 patients with systemic lupus erythematosus had cofactor dependent anticardiolipin, 10 patients had antibodies to beta 2-glycoprotein I and 4 patients had positive VDRL test. 5 of 34 plasma samples were lupus anticoagulant positive. 19 patients with systemic lupus erythematosus had 14 neuropsychiatric disorders, 9 cardiovascular diseases, 7 thrombocytopenia, 6 histories of recurrent abortion and fetal loss, 5 livedo reticularis and 3 thromboembolic events in all of them had detected antibodies to cofactor dependent anticardiolipin, while these complications were diagnosed in 39 anticardiolipin negative patients much more rarely. The results of this retrospective study suggest that significant association exists between the presence of cofactor dependent anticardiolipin and symptoms of antiphospholipid syndrome in systemic lupus erythematosus.
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PMID:[Clinical significance of antiphospholipid autoantibodies in lupus erythematosus]. 979 52

The target of many anti-phospholipid autoantibodies (aPL) has been shown to be a complex between anionic phospholipid and the plasma protein beta2-glycoprotein I (beta2GPI) or the protein beta2GPI alone. As aPL binding studies have been performed almost exclusively in vitrothe identity of the natural target and/or immunogen for aPL in vivo remains undetermined. The anionic phospholipids of cell membranes represent an important potential target and immunogen for aPL. Although anionic phospholipids are normally absent from the extracellular surface of cell membranes, they redistribute from the inner to the outer leaflet during apoptosis. We have previously shown that beta2GPI binds selectively to the surface of apoptotic, but not viable, cells, and that binding of beta2GPI to the surface of apoptotic cells generates an epitope recognized by aPL from patients with primary aPL syndrome and systemic lupus erythematosus. We show here that immunization of non-autoimmune mice with beta2GPI combined with, or bound to, apoptotic cells induces aPL and lupus anticoagulant activity. Generation of aPL required heterologous beta2GPI, and occurred upon immunization with apoptotic cells and beta2GPI by three different routes of administration. Importantly, for intravenous immuniz-ations, generation of aPL occurred only when apoptotic cells and beta2GPI were injected together, but not when either was injected alone, suggesting that cell-bound beta2GPI is the true immunogen for production of aPL. Unlike other models of induced aPL, adjuvant was not an absolute requirement. Induced aPL reacted with murine, as well as bovine, beta2GPI, suggesting that heterologous beta2GPI bound to apoptotic cells can break tolerance and induce auto-antibodies reactive with autologous beta2GPI. Combined with our previous data, these results show that apoptotic cells can serve as both immunogens and natural targets for aPL.
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PMID:Induction of anti-phospholipid autoantibodies by beta2-glycoprotein I bound to apoptotic thymocytes. 980 24

It has become clear that beta2-glycoprotein I (beta2GPI) is the most common and best-characterised antigenic target for 'antiphospholipid' (aPL) autoantibodies. These antibodies preferentially bind beta2GPI that has been immobilised on anionic phospholipid membranes or certain synthetic surfaces. These surfaces appear to act by increasing antigen density to allow binding of intrinsically low-affinity anti-beta2GPI autoantibodies. Binding of beta2GPI in fluid phase is weak and requires high concentrations of beta2GPI. Our understanding of the pathophysiology of the 'Antiphospholipid' Syndrome (APS) has increased exponentially with the number of studies into the interactions of aPL antibodies and beta2GPI.
Lupus 1998
PMID:Beta2-glycoprotein I: target antigen for 'antiphospholipid' antibodies. Immunological and molecular aspects. 981 63

Apolipoprotein H (apoH; also known as beta2-glycoprotein I), is an essential cofactor for the binding of certain antiphospholipid antibodies (APA) to anionic phospholipid. The gene coding for apoH is polymorphic, with the occurrence of several common alleles in the general population. This genetically determined variation can effect the binding of apoH to anionic phospholipids and consequently the production of APA. Our group has identified two common mutations at codons 306 (Cys-->Gly) and 316 (Trp-->Ser) in the fifth domain of apoH which affect the binding of apoH to anionic phospholipids (phosphatidylserine or cardiolipin). ApoH from serum samples homozygous for each of these mutations or compound heterozygotes for both mutations showed no binding with anionic phospholipids on ELISA. In vitro mutagenesis and transient expression of these mutations in COS-1 cells followed by cardiolipin binding studies confirmed that Gly306 and Ser316 are causative mutations. Our data indicate that the fifth domain of apoH is essential for anionic phospholipid binding and genetically determined variation in this domain can affect the production of apoH-dependent APA.
Lupus 1998
PMID:Genetics of apolipoprotein H (beta2-glycoprotein I) and anionic phospholipid binding. 981 64

Anticardiolipin antibodies (aCL) found in sera from patients with antiphospholipid syndrome recognize a cryptic epitope that appears on the beta2-glycoprotein I (beta2-GPI) molecule when beta2-GPI interacts with a lipid membrane composed of negatively charged phospholipid or when beta2-GPI is adsorbed on a polyoxygenated polystyrene plate. A homology based model of beta2-GPI was constructed based on the NMR coordinates of sushi domains of human factor H. The conformation was like a cylinder consisting of five domains, its IV and V domains being glued by electrostatic interaction. We used phage-displayed random peptide libraries to search the epitopes of human aCL. Structures similar to consensus sequences selected by a biopanning method was found on domain IV of beta2-GPI.
Lupus 1998
PMID:Epitopes on beta2-GPI recognized by anticardiolipin antibodies. 981 65

Lupus anticoagulant antibodies form a heterogeneous group of antiphospholipid antibodies with rather poorly defined antigens. The role that phospholipid-binding proteins play in lupus anticoagulant antibody activity is a subject of current investigation. Several candidate proteins have been proposed, including beta2-glycoprotein I (beta2GPI), prothrombin, and annexin V. As beta2GPI-dependent lupus anticoagulants will be reviewed elsewhere in this issue, this paper will focus on the involvement of prothrombin and annexin V in lupus anticoagulant activity. Evidence for a role for these proteins in the reactivity and induction of lupus anticoagulant antibodies will be discussed, as well as an apparent requirement for both phospholipid and phospholipid-binding protein. The data presented here suggest that some lupus anticoagulant antibodies recognize and may be induced by complexes of phospholipid and phospholipid-binding proteins, in particular, phospholipid and prothrombin or annexin V.
Lupus 1998
PMID:Lupus anticoagulant antibodies: recognition of phospholipid-binding protein complexes. 981 68

Prothrombin is a common antigenic target of antiphospholipid antibodies, since anti-prothrombin antibodies are detected in about 50-90% of the patients. To allow proper immune recognition, prothrombin must be adsorbed on suitable anionic surfaces. The epitope(s) have not yet been identified: the majority of anti-prothrombin antibodies appear to be of poly- or oligoclonal nature. Anti-prothrombin antibodies, either alone or in combination with anti-beta2-glycoprotein I antibodies, are responsible for the lupus anticoagulant activity of about 75% of the cases of phospholipid-dependent inhibitors of coagulation. The two antibodies may be discriminated by means of specific coagulation profiles generated by the comparison of the ratio of the Kaolin Clotting Time (KCT) and the dilute Russell's Viper Venom Time (dRVVT): the KCT profile, which mainly reflects the presence of anti-prothrombin antibodies and the dRVVT profile, which is mostly associated with anti-beta2-glycoprotein I antibodies. This distinction, although somewhat artificial, may be clinically useful, since the KCT profile identifies patients at low risk to develop thrombosis. Similarly, most of the studies that measured anti-prothrombin antibodies by ELISA failed to find a significant association with thrombosis. In conclusion, the clinical relevance of these antibodies has not yet been established.
Lupus 1998
PMID:Prothrombin as cofactor for antiphospholipids. 981 70

The clinical associations of antiphospholipid antibodies (aPL) are well recognized but the mechanism(s) causing the production of these antibodies are not yet known. We demonstrated the induction of pathogenic aPL antibodies that caused intrauterine fetal death and transverse myelopathy due to spinal cord infarction in mice by immunization with foreign beta2GPI. We also induced aPL and anti-beta2-GPI in mice by immunization with PL-binding viral peptides and hypothesized that in APS patients, aPL may be induced by beta2GPI-like-PL-binding products of common human bacteria and viruses.
Lupus 1998
PMID:Origin of antiphospholipid antibodies: induction of aPL by viral peptides. 981 74

The relationship between presence of anti-beta2-glycoprotein I autoantibodies (abeta2-GPI) and history of thrombosis is now widely known. However, differences in the methodology of abeta2-GPI detection have made the comparison of data from different laboratories extremely difficult. We discuss the significance of abeta2-GPI of the IgG, IgM and IgA isotypes, and our approach to developing an easier and more reproducible method for the detection of this autoantibody. In addition, we present data that shows that commercially available enzyme immunoassay plates differ regarding detectability of abeta2-GPI. Since the clinical significance of this heterogeneity is presently unclear, the set-up of the detection systems and interpretation of data need great care.
Lupus 1998
PMID:Anti-beta2-glycoprotein I antibodies. 981 83

It is widely hypothesized that autoantibodies directly contribute to the prothrombotic state in the antiphospholipid syndrome (APS). The discovery that antiphospholipid autoantibodies are specific for phospholipid-binding plasma proteins (beta2-glycoprotein I, prothrombin, etc.) has allowed a much more precise investigation of the interactions of autoantibodies and antigens, and the effects of these interaction on hemostasis. Recent studies suggest that two types of interactions may be important in the pathophysiology of APS: (1) antibody cross-linking of membrane bound antigens may alter the kinetics of phospholipid-dependent reactions; and (2) antibody cross-linking of antigens bound to cell surface receptors may trigger signal transduction and cellular activation. In light of these findings, previous reports implicating various mechanisms of autoantibody-mediated thrombosis are being re-evaluated.
Lupus 1998
PMID:Mechanisms of autoantibody-mediated thrombosis. 981 87


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