Laboratory diagnosis of lupus anticoagulants

Pathology ◽  
1992 ◽  
Vol 24 ◽  
pp. 18
Author(s):  
T. Exner
Keyword(s):  
Laboratory Diagnosis ◽  
Lupus Anticoagulants

Antiphospholipid Syndrome: Diagnostic Aspects of Lupus Anticoagulants

2001 ◽  
Vol 86 (07) ◽  
pp. 83-91 ◽  
Author(s):  
J. Arnout
Keyword(s):  
Monoclonal Antibodies ◽  
Antiphospholipid Syndrome ◽  
Autoimmune Disorder ◽  
Coagulation Factors ◽  
Laboratory Diagnosis ◽  
Anticardiolipin Antibodies ◽  
Lupus Anticoagulants ◽  
Glycoprotein I ◽  
Antigen Antibody

SummaryAntiphospholipid syndrome (APS) is an autoimmune disorder in which antiphospholipid antibodies (aPL) are thought to be involved in the development of venous and/or arterial thrombosis. APL found in this syndrome are antibodies directed against a variety of phospholipid (PL) binding-proteins of which β2-glycoprotein I (β2GPI) and prothrombin are considered to be the major antigens. Some of these antibodies prolong PL-dependent clotting reactions and are termed lupus anticoagulants (LA). Autoimmune aPL which bind through β2GPI to cardiolipin are called anticardiolipin antibodies (aCL). Clinical studies indicate that LA is a stronger risk factor for thrombosis than aCL. The production of monoclonal antibodies against β2GPI and prothrombin has enabled us to understand the mechanism by which LA prolong coagulation in vitro. LA form bivalent antigen-antibody complexes with increased affinity for PL which compete with coagulation factors for the same catalytic surface. These LA positive monoclonal antibodies may be helpful in further improving the laboratory diagnosis of LA.

Laboratory Diagnosis of Lupus Anticoagulants

2002 ◽  
Vol 87 (05) ◽  
pp. 854-858 ◽  
Author(s):  
Veena Chantarangkul ◽  
Marigrazia Clerici ◽  
Caterina Bressi ◽  
Pier Mannucci ◽  
Armando Tripodi
Keyword(s):  
Diagnostic Criteria ◽  
Laboratory Diagnosis ◽  
Time Difference ◽  
Clotting Time ◽  
Diagnostic Efficacy ◽  
Lupus Anticoagulants

SummaryResidual platelets in plasma are considered detrimental after freezing-thawing, as phospholipids released from ruptured platelets may quench lupus anticoagulants (LA). We aimed at assessing the effect of residual platelets after freezing-thawing plasmas tested with two procedures for LA. Blood from 52 patients suspected of having LA were centrifuged at 2,500 g. Plasmas were subdivided into 2 aliquots. One was filtered to remove residual platelets and both were frozen and stored at –70° C. Silica clotting time (SCT) at low and high phospholipid concentrations and Staclot® LA with and without Hexagonal phospholipids were performed on thawed plasmas. Plasmas were considered LA-positive when both SCT and Staclot® LA performed on filtered plasmas were diagnostic for LA. Forty-two of 52 plasmas fulfilled the diagnostic criteria and were retained for subsequent analysis. SCT on non-filtered plasmas was diagnostic for LA in 42 of 42 plasmas. Though the median (range) percentage correction recorded after phospholipids addition for filtered plasmas, i. e., 67% (36%-83%) was reduced to 54% (25%-81%) for non-filtered plasmas (p <0.001), it was still above the cut-off (i. e., 20.9%). Staclot® LA on non-filtered plasmas was diagnostic for LA in 42 of 42 plasmas. Though the median (range) clotting time difference recorded after phospholipid addition for filtered plasmas, i. e., 40.8 (10-103.5) s was reduced to 31.7 (2.8-88.8) s for non-filtered plasmas (p <0.001), it was still above the cut-off (i. e., 1.7 s). In conclusion, residual platelets do not affect the diagnostic efficacy of SCT and Staclot® LA. However, the fact that the percentage correction for SCT and the clotting time difference for Staclot® LA are reduced by residual platelets, suggests that weak LA may be lost upon freezing-thawing non-filtered plasmas.

Laboratory Diagnosis of Lupus Anticoagulants for Patients on Oral Anticoagulant Treatment

2002 ◽  
Vol 88 (10) ◽  
pp. 583-586 ◽  
Author(s):  
Veena Chantarangkul ◽  
Marigrazia Clerici ◽  
Pier Mannucci ◽  
Armando Tripodi
Keyword(s):  
Gold Standard ◽  
Low Cost ◽  
Oral Anticoagulants ◽  
Laboratory Diagnosis ◽  
Anticoagulant Treatment ◽  
Clotting Time ◽  
Oral Anticoagulant Treatment ◽  
Diagnostic Efficacy ◽  
Lupus Anticoagulants ◽  
Normal Plasma

SummaryThe detection of lupus anticoagulant (LA) in plasmas from patients on oral anticoagulants is problematic because of their prolonged clotting times. Mixing of patients and normal plasmas prior to testing for LA is employed to overcome this problem. We investigated the diagnostic efficacy of silica clotting time (SCT) and dilute Russell viper venom test (dRVVT) performed at low and high phospholipid concentrations, to diagnose LA in patients on oral anticoagulants, in comparison with Staclot® LA (Stago) performed with and without hexagonal phospholipids and normal plasma. Case materials were 114 filtered plasmas from patients on oral anticoagulants with (n = 62) and without (n = 52) the antiphospholipid syndrome. Plasmas were considered LA-positive when Staclot® LA (taken as the “gold standard”) was diagnostic for LA. Forty-four plasmas were positive with Staclot® LA. Forty and 39 of these were also positive with SCT and dRVVT (sensitivity relative to Staclot® LA was 91% and 89%, respectively). Seventy plasmas were negative with Staclot® LA. Three of these were positive with both SCT and dRVVT (specificity relative to Staclot® LA was 96%). Kappa values for measure of agreement were 0.87 and 0.85 (p <0.001), respectively. In conclusion, SCT and dRVVT performed at low and high phospholipid concentrations without normal plasma can be considered as reliable as Staclot® LA peformed with hexagonal phospholipids and normal plasma to diagnose LA in patients on oral anticoagulants. Advantages of SCT and dRVVT over Staclot® LA are easy automation, no need for normal plasma and relatively low cost.

Monoclonal Antibodies against Beta-2-Glycoprotein I: Use as Reference Material for Lupus Anticoagulant Tests

1998 ◽  
Vol 79 (05) ◽  
pp. 955-958 ◽  
Author(s):  
J. Arnout ◽  
M. Vanrusselt ◽  
C. Wittevrongel ◽  
J. Vermylen
Keyword(s):  
Monoclonal Antibodies ◽  
Laboratory Diagnosis ◽  
Poor Agreement ◽  
Control Material ◽  
Lupus Anticoagulants ◽  
Glycoprotein I ◽  
Coefficients Of Variation ◽  
And Control ◽  
Murine Monoclonal Antibodies ◽  
Control Batch

SummaryThe laboratory diagnosis of lupus anticoagulants (LA) remains difficult despite internationally accepted guidelines for its detection. Several interlaboratory surveys have shown poor agreement between laboratories. Further standardization of LA testing will to a large extent depend on better insights on the mechanisms by which LA affect phospholipid-dependent coagulation assays as well as on the availability of well characterized and internationally accepted reference materials and control specimens. We recently raised a series of murine monoclonal antibodies against human β2GPI (anti-β2GPI moabs), a phospholipid-binding protein directly involved in the interaction between certain lupus anticoagulants and phospholipids. In this study we report on the use of LA positive anti-β2GPI moabs as easy to handle reference and control material. The relative LA responsiveness of various phospholipid-dependent clotting assays was determined on plasmas spiked with such moabs and compared well with that determined on LA positive plasma samples. Plasmas spiked with LA positive anti-β2GPI moabs were also used as control specimens to study the interlaboratory precision of LA testing. With these control specimens, low interassay coefficients of variation were obtained. Our results indicate that LA positive anti-β2GPI moabs have potential for the production of control specimens that could be made available to routine hemostasis laboratories to assess intra-laboratory precision of LA testing and to manufacturers to control batch-to-batch variability of their reagents.

The Textarin/Ecarin Ratio: A Confirmatory Test for Lupus Anticoagulants

1993 ◽  
Vol 70 (06) ◽  
pp. 0925-0931 ◽  
Author(s):  
Douglas A Triplett ◽  
Kurt F Stocker ◽  
Gail A Unger ◽  
Linda K Barna
Keyword(s):  
Protein Fraction ◽  
Anticardiolipin Antibody ◽  
Laboratory Diagnosis ◽  
Test System ◽  
Confirmatory Test ◽  
Factor V ◽  
Drug Induced ◽  
Lupus Anticoagulants ◽  
Specific Inhibitors

SummaryLupus anticoagulants (LA) are immunoglobulins (IgG, IgM, IgA or a mixture) which interfere with in vitro phospholipid (PL) dependent tests of coagulation (e.g. APTT, KCT, dilute Russell Viper Venom Time). LA are heterogeneous; consequently, the laboratory diagnosis is difficult and relies on multiple tests. We have developed a sensitive and relatively specific confirmatory test system based on fractions of two snake venoms. Textarin®, a protein fraction of Pseudonaja textilis venom (Australian Eastern brown snake), activates prothrombin in the presence of PL, factor V and calcium ions. Ecarin, a protein fraction of Echis carinatus venom, will activate prothrombin in the absence of any cofactors. The activation of prothrombin by Textarin yields thrombin while Ecarin yields meizothrombin. In the presence of LA, the Textarin time is prolonged and the Ecarin time is unaffected. The test results are reported as a ratio of Textarin/Ecarin times (abnormal greater than 1.3). We have evaluated this test system in the following patient populations: LA positive, therapeutically heparinized, stable oral anticoagulated, liver disease, routine preoperative, anticardiolipin antibody positive LA negative, hemophilia A, various other hereditary factor deficiencies or dysfunctional proteins, and specific inhibitors of factor V and factor VTII. The LA positive patients represented a mixed population of autoimmune disease, drug-induced and post-infectious states. Our findings indicate the sensitivity of the Textarin/Ecarin system in the confirmation of LA. In order to use the test system most effectively, it is recommended to incorporate poly-brene with Textarin when evaluating heparinized samples. Factor V deficiency and specific inhibitors of factor V yielded, in some instances, false positive results.

scholarly journals Laboratory Testing for Lupus Anticoagulants: A Review of Issues Affecting Results

2007 ◽  
Vol 53 (9) ◽  
pp. 1629-1635 ◽  
Author(s):  
Armando Tripodi
Keyword(s):  
Correct Diagnosis ◽  
Anticoagulation Therapy ◽  
Laboratory Diagnosis ◽  
Specific Test ◽  
Lupus Anticoagulants ◽  
Pregnancy Morbidity ◽  
Clinical Events ◽  
Future Direction ◽  
The Many ◽  
And Storage

Abstract Background: Lupus anticoagulants (LA) are a heterogeneous class of immunoglobulins. Persistent LA positivity is a risk factor for the occurrence and recurrence of venous/arterial thromboembolism and/or pregnancy morbidity and qualifies the patient for anticoagulation therapy. The laboratory diagnosis for LA that is used for crucial decision-making about the optimal duration of the therapy rests entirely on diagnostic criteria. These criteria are based on the prolongation of phospholipid-dependent tests not corrected upon mixing patient and normal plasmas, with confirmation provided by the evidence that the anticoagulant is directed against proteins bound to negatively charged phospholipids. Aims: This article reviews issues related to the diagnosis of LA, including the effect of preanalytical variables, choice of tests, results interpretation of screening, mixing and confirmation procedures, patients to be investigated, and transmission of results. Unresolved issues and future direction for research on laboratory diagnosis are also discussed. Methods: Search of PubMed with the key term “lupus anticoagulant” plus articles and unpublished data known to the author. Results and Conclusions: The preanalytical variables (i.e., plasma preparation and storage before analysis) as well as the diagnostic steps to detect LA present potential problems that undermine the process of making a correct diagnosis. A truly specific test for LA detection is badly needed, but its development may require understanding of the mechanisms associated with the occurrence of clinical events. Until then, clinical laboratories should rely on the existing procedures, which must be applied with caution and awareness of the many issues that may affect their results.

Many faces of lupus anticoagulants

Lupus ◽  
1998 ◽  
Vol 7 (2_suppl) ◽  
pp. 18-22 ◽  
Author(s):  
DA Triplett
Keyword(s):  
Fetal Loss ◽  
Laboratory Diagnosis ◽  
Anticardiolipin Antibodies ◽  
Screening Tests ◽  
Factor Viii Inhibitor ◽  
Lupus Anticoagulants ◽  
Venous Thromboembolic Events ◽  
Venous Thromboembolic ◽  
Confirmatory Tests

Lupus anticoagulants (LA) are immunoglobulins which inhibit one or more of the in-vitro phospholipid (PL) dependent tests of coagulation. Virtually any physician may encounter LA-positive patients. Such patients present with a variety of diagnostic challenges including arterial and venous thromboembolic events, recurrent fetal loss, TIAs, livedo reticularis, etc. LA and anticardiolipin antibodies (ACA) are the most common cause of acquired thrombophilia. Consequently, it is imperative for clinicians and laboratorians to work together in establishing the diagnosis of LA/ACA. The laboratory diagnosis of LA requires careful adherence to the SSC Subcommittee on Lupus Anticoagulants/Phospholipid-dependent Antibodies guidelines. Four sequential steps are required, including: screening tests, mixing studies (to establish the presence of an inhibitor), confirmatory tests based on increased or altered PL concentrations, and ruling out other coagulopathies (for example, factor VIII inhibitor).

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