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)

NZW x BXSB F1 (W/B F1) male mice develop systemic lupus-like disease, and several autoantibodies, circulating immune complexes, and lupus nephritis become apparent. The abnormally high incidence of degenerative coronary vascular disease with myocardial infarction and thrombocytopenia due to the presence of both platelet-associated antibodies and circulating antiplatelet antibodies in this animal has been reported. We found that W/B F1 male mice produced autoantibodies against cardiolipin (aCL) and that the titer of aCL increases with age. aCL from W/B F1 male mice were mainly IgG and binding activity to cardiolipin was aCL-cofactor (beta 2-glycoprotein I (beta 2-GPI)) dependent. We developed monoclonal aCL from these animals and examined specificity of the autoantibodies. All the mAb used reacted with the negatively charged phospholipids, cardiolipin, phosphatidylserine, and phosphatidylinositol, and some reacted with platelets and DNA. The addition of human or mouse beta 2-GPI enhanced the titer for monoclonal aCL from the W/B F1 mice. From the results of competitive inhibition enzyme immunoassay with monoclonal aCL and purified beta 2-GPI, aCL from the W/B F1 mice recognized the complex of CL and beta 2-GPI. The W/B F1 male mouse may be an appropriate model for use in studies on the pathologic significance of aCL in patients with antiphospholipid syndrome.
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PMID:Anticardiolipin antibodies in NZW x BXSB F1 mice. A model of antiphospholipid syndrome. 163 62

New details have been added to the description of the antiphospholipid antibody syndrome. These include quantitation of risk of stroke; delineation of an associated acute occlusive vasculopathy syndrome, including its pathology; increased awareness of the association of adrenal insufficiency with antiphospholipid antibody; new demonstration of placental pathology in cases of fetal death; and new details on the persistence or transience of antibody in patients with systemic lupus erythematosus. There are several animal models for the antiphospholipid antibody syndrome. Assay standardization and reproducibility issues, more for the lupus anticoagulant than for the enzyme-linked immunosorbent assay for antiphospholipid antibody, remain as important barriers to progress. Antibody characteristics of activity, isotype, and subclass must be considered in assay interpretation; antigen characteristics of fatty acid chain and lipid phase are also important variables. Other circulating proteins may have clinical importance. Several laboratories have commented that antiphospholipid antibody interferes with protein C. A cofactor, apolipoprotein H, enhances binding of some antiphospholipid IgG antibodies. Other phospholipid-binding proteins are known. Isolation, purification, and perhaps cloning of many of these factors should lead to a better understanding of the pathogenesis of the syndrome.
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PMID:Antiphospholipid antibody and antiphospholipid antibody syndrome. 183 43

Lupus anticoagulants are a group of antibodies commonly found in patients with autoimmune diseases such as systemic lupus erythematosus. Lupus anticoagulants inhibit phospholipid dependent coagulation and may bind to negatively charged phospholipids. Recent studies have suggested an association between anti-beta 2-glycoprotein I and a lupus anticoagulant, whose activity is frequently dependent on the presence of beta 2-glycoprotein I. Based on these observations, the effect of anti-beta 2-glycoprotein I on the autoactivation of factor XII in plasma was investigated. Autoactivation initiated by the presence of negatively charged phospholipids, but not by sulfatide, was strongly inhibited by immunoaffinity purified anti-beta 2-glycoprotein I. The dose-response curve of anti-beta 2-glycoprotein I was identical with that of a precipitating antibody, showing no inhibition at low and high antibody dilutions and maximal inhibition at an intermediate dilution. At high antibody concentrations, an increased rate of factor XIIa activation was observed. This increase was of the same magnitude as the decreased rate observed in plasma supplemented with the same amount of beta 2-glycoprotein I as in the plasma itself. This confirms the inhibitory effect of beta 2-GP-I on the contact activation and shows that inhibition is effective on the autoactivation of factor XII in plasma. The inhibitory action of beta 2-glycoprotein I was independent of the inhibition caused by the anti-beta 2-glycoprotein I/beta 2 glycoprotein I complex suggesting a synchronized inhibition of factor XII autoactivation by beta 2-glycoprotein I and anti-beta 2-glycoprotein I. The inhibition caused by the antibody is suggested to be caused by a reduced availability of negatively charged phospholipids due to the binding of the anti-beta 2-GP-I/beta 2-GP-I complex. This complex may be a lupus anticoagulant.
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PMID:Synchronized inhibition of the phospholipid mediated autoactivation of factor XII in plasma by beta 2-glycoprotein I and anti-beta 2-glycoprotein I. 748 6

Antiphospholipid (aPL) antibodies include anticardiolipin (aCL) and lupus anticoagulant (LA) antibodies. LA antibodies recognize the complex of lipid-bound (human) prothrombin, in this way inhibiting the phospholipid-dependent coagulation reactions, whereas aCL antibodies are directed towards beta 2-glycoprotein I (beta 2-GPI) bound to an anionic lipid surface. According to their behavior in coagulation reactions, we have divided aCL antibodies into two groups: aCL-type A, which inhibit the phospholipid-dependent coagulation reactions because they enhance the binding of beta 2-GPI to the procoagulant phospholipid surface; and aCL-type B antibodies, which are devoid of anticoagulant properties. We report the distinctive laboratory and clinical profiles of 25 patients with well-characterized, phospholipid-dependent inhibitor of coagulation. Fourteen patients had LA antibodies (aCL-type B were concomitantly present in 10 cases, while in the other four, aCL titer was normal), and the other 11 had aCL-type A antibodies. The laboratory evaluation of the two groups showed the dilute Russell viper venom time (dRVVT) to be the most abnormal coagulation test in the aCL-type A-positive group, whereas the kaolin clotting time (KCT) was the most abnormal assay in the LA-positive group. In fact, the ratios of the coagulation times of patient plasma over normal pooled plasma (mean +/- standard deviation) for LA versus aCL-type A antibodies were 1.48 +/- 0.27 versus 2.20 +/- 0.42, P = .0001, and 2.22 +/- 0.42 versus 1.50 +/- 0.42, P = .0003, for the dRVVT and KCT, respectively. No differences were observed either in the ratios of the activated partial thromboplastin times and the prothrombin times or the plasma levels of beta 2-GPI and prothrombin. Conversely, aCL titers were significantly higher in aCL-type A-positive patients (147 +/- 44 U) than in the LA-positive group (61 +/- 55 U; P = .0003). We ruled out the possibility that platelet contamination of plasma could account for the observed coagulation profiles, as the two patterns were reproduced in platelet-free plasma. In addition, we performed clotting tests in plasma in the presence of phospholipids and calcium after addition of factor IXa or factor Xa. The assay performed with factor Xa was more sensitive to the presence of aCL-type A antibodies, while the assay performed with factor IXa was preferentially sensitive to LA-containing plasmas, supporting the earlier findings with the dRVVT and KCT assays.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Kaolin clotting time and dilute Russell's viper venom time distinguish between prothrombin-dependent and beta 2-glycoprotein I-dependent antiphospholipid antibodies. 760 91

A group of anticardiolipin antibodies (aCL) require beta 2-glycoprotein I (beta 2GPI) to recognize their target, which might be located on endothelial cells (EC) and/or platelets. Following incubation with epithelial cells, 13 of 30 lupus sera retained EC-reactive antibodies of the IgG, IgA and IgM isotypes. Associated aCL and anti-phosphatidylethanolamine antibodies were partly absorbed on eC as well as EC. The former antibodies were more efficiently removed in the presence than in the absence of the latter. The presence of beta 2GPI in the affinity-purified aCL preparations may explain their binding to EC, as this cross-reaction was abrogated by the removal of the cofactor and restored by its re-introduction. Seventy four per cent of EC were faintly stained with polyclonal or monoclonal antibody directed to the cofactor. The beta 2GPI mediated aCL binding to EC membranes could this be influential in the development of thrombosis and/or thrombocytopenia in aCL-positive patients.
Lupus 1995 Jun
PMID:Role of beta 2-glycoprotein I in the antiphospholipid antibody binding to endothelial cells. 765 84

A 26-year-old man with systemic lupus erythematosus (SLE) and a history of acute myocardial infarction developed portal hypertension accompanied by abnormal liver function and esophageal varices. As his clinical course suggested the possibility of antiphospholipid syndrome, a titer of anticardiolipin antibody (aCL) was serially measured using an enzyme immunoassay with beta 2-glycoprotein I as a cofactor. The titer of aCL increased with the development of portal hypertension, and promptly decreased with the improvement of liver function just after corticosteroid therapy. The long-term course in this case suggests that aCL may cause portal hypertension associated with SLE.
Lupus 1995 Jun
PMID:Portal hypertension associated with anticardiolipin antibodies in a case of systemic lupus erythematosus. 765 97

We have previously demonstrated that patients with cirrhosis may be positive for lupus anticoagulant and anticardiolipin antibodies. The prevalence and clinical value of antiphospholipid antibodies in cirrhosis have never been described. Besides, it has not yet been determined if serum levels of beta-2-glycoprotein I, which is synthesized by the liver and mediates the interaction between cardiolipin and anticardiolipin antibodies affects lupus anticoagulant detectability in cirrhosis. We evaluated the prevalence of lupus anticoagulant in 63 patients with cirrhosis and related it to beta-2-glycoprotein I serum levels. We also analyzed whether lupus anticoagulant and anticardiolipin antibodies were associated with previous thrombotic complications. Eleven patients (18%) were lupus anticoagulant positive; 14 (22%) had high values of anticardiolipin antibodies. Fourteen patients had a previous history of splanchnic venous thrombosis (n = 9) or thrombophlebitis (n = 5). A significant association between lupus anticoagulant (p = 0.0001), anticardiolipin antibodies (p = 0.0001) and venous thrombosis was found. Patients with severe liver failure had significantly lower beta-2-glycoprotein I levels than those with moderate (p < 0.01) or low (p < 0.001) hepatic insufficiency. Among 14 anticardiolipin antibodies positive patients, six with severe liver failure were lupus anticoagulant negative and had beta-2-glycoprotein I values below 100 micrograms/ml. In four of these, basal values of dilute activated partial thromboplastin time were not modified by the addition of 50 micrograms/ml of exogenous beta-2-glycoprotein I. This study shows that antiphospholipid antibodies are relatively frequent in cirrhosis and that beta-2-glycoprotein I levels are not so low as to affect lupus anticoagulant detectability.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Prevalence of lupus anticoagulant in patients with cirrhosis: relationship with beta-2-glycoprotein I plasma levels. 769 32

We studied the effect of beta 2-GPI on binding of antibodies in sera from patients with leprosy and patients with the antiphospholipid syndrome (APS) to CL in enzyme-linked immunosorbent assays (ELISAs). Increased levels of IgG aCL were detected in 59 of 61 leprosy patients' sera by the standard aCL-ELISA in the presence of bovine beta 2-GPI and in 60 of the 61 leprosy patients' sera by the modified aCL-ELISA without beta 2-GPI. When tested by both aCL-ELISAs on the same plate, 10/31 leprosy sera and 9/10 APS sera bound better in the standard aCL-ELISA, 16/31 leprosy sera bound better in the modified aCL-ELISA and in five leprosy and one APS sera the difference was not significant. A dose-dependent enhancing effect of beta 2-GPI on the leprosy and APS sera binding to CL was confirmed using purified human beta 2-GPI. Enhanced binding was seen if beta 2-GPI was added either before or together with the test serum. In 11/61 leprosy sera increased levels of IgG antibodies against beta 2-GPI were found by ELISA. Leprosy anti-beta 2-GPI antibodies appear to be a separate antibody population recognizing only beta 2-GPI adsorbed on the ELISA plate. These results demonstrate heterogeneity of leprosy aCL with respect to their beta 2-GPI requirement for binding to CL.
Lupus 1994 Dec
PMID:Anticardiolipin antibodies in infections are heterogenous in their dependency on beta 2-glycoprotein I: analysis of anticardiolipin antibodies in leprosy. 770 10

We investigated the clinical significance of IgG beta 2-glycoprotein I (GPI)-dependent anticardiolipin antibodies (aCL) in rheumatic diseases. Three hundred and seventeen patients were entered. They consisted of 133 patients with SLE, 60 with RA, 45 with SSc, 37 with PM, 23 with overlap syndrome (overlap), and 19 with unclassified connective tissue disease (UCTD). IgG beta 2-GPI-dependent aCL were examined by ELISA. While IgG beta 2-GPI-dependent aCL were detected in 13% of patients with SLE, these aCL were positive in two patients with SSc, two with overlap and 14 with UCTD. A significant association between IgG beta 2-GPI-dependent aCL and thrombosis was found. Clinical manifestations were studied in 32 patients with secondary APS based on SLE and 14 with primary APS (PAPS). Incidence of malar rash, arthritis, renal disorder, leucopenia, immunological disorders and hypocomplementemia were significantly less frequent in patients with PAPS. IgG beta 2-GPI-dependent aCL were detected in all patients with PAPS and in 34% of secondary APS. This difference was significant. These data suggest that IgG beta 2-dependent aCL are useful for identifying a subset in patients with APS.
Lupus 1995 Feb
PMID:Disease distribution of beta 2-glycoprotein I-dependent anticardiolipin antibodies in rheumatic diseases. 775 7

beta 2-Glycoprotein I (beta 2-GPI) is a cofactor in the recognition of a phospholipid antigen, cardiolipin, by anticardiolipin antibodies in autoimmune diseases such as systemic lupus erythematosus. We examined the interaction of various forms of bovine beta 2-GPI, such as its intact form, desialylated form (Asialo beta 2-GPI), N-terminal domain (domain I) and the modified forms of beta 2-GPI and Asialo beta 2-GPI with nicks in their C-terminal domains (domain 5), with phospholipid liposomes under different conditions of pH and ionic strength. We found that at neutral pH and low ionic strength beta 2-GPI bound to liposome membranes containing cardiolipin with a dissociation constant (Kd) of 10(-8) M. Phosphatidylglycerol, phosphatidylserine, phosphatidic acid or phosphatidylinositol bound to beta 2-GPI, but phosphatidylcholine did not. We also found that domain I and Asialo beta 2-GPI bound to cardiolipin with Kd values of 10(-6) and 10(-8) M, respectively. At neutral pH and both low and high ionic strengths, the affinities of nicked forms of beta 2-GPI and Asialo beta 2-GPI for cardiolipin were lower than those of intact forms but similar to that of domain 1.
Lupus 1995 Feb
PMID:Structure and function of beta 2-glycoprotein I: with special reference to the interaction with phospholipid. 775 8


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