Standardization of antiphospholipid antibody assays. Where do we stand?

Devreese, Katrien

doi:10.1177/0961203312439335

Cited by 70 publications

(70 citation statements)

References 23 publications

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“…A major problem within APS is the variability between different commercial anti-β 2 GPI available assays [2], [12], [13], [14]. External quality Control of diagnostic Assays and Tests Disagreement (ECAT) reports showed that laboratories obtain good results for negative or clearly positive samples.…”

Section: Discussionmentioning

confidence: 99%

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Variability in Exposure of Epitope G40-R43 of Domain I in Commercial Anti-Beta2-Glycoprotein I IgG ELISAs

et al. 2013

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BackgroundA major problem for diagnosing the antiphospholipid syndrome (APS) is the high variability between commercial anti-β2glycoprotein I (β2GPI) assays. Predominantly antibodies reactive against cryptic epitope Glycine40-Arginine43 (G40-R43) in domain I are associated with an increased risk for thrombosis. Upon interaction with anionic surfaces β2GPI opens up, thereby exposing G40-R43.ObjectivesTo examine whether suboptimal exposure of epitope G40-R43 explains the variations in results observed between commercial assays.MethodsTwo patient-derived monoclonal antibodies were tested on neutral versus anionic plates. Antibody P1-117 reacts with G40-R43 in the open conformation while P2-6 recognizes β2GPI irrespective of its conformation. These antibodies were tested in commercial anti-β2GPI assays (A–E).ResultsIn assay A, both antibodies showed equal reactivity towards β2GPI, indicating that all the β2GPI exposes G40-R43. In other assays P1-117 displayed lower reactivity than P2-6, demonstrating reduced G40-R43 availability. To exclude influences of other assay features, reactivity was re-examined on plates of assay A and B using the protocol/reagents from each assay. In all combinations, reactivity of both antibodies on a plate was comparable to results obtained with its own protocol/reagents, suggesting that the coating, rather than other assay components, accounts for the observed differences. In two patient cohorts we demonstrated that a number of domain I-reactive samples are missed in assays characterized by a decreased exposure of epitope G40-R43.ConclusionsExposure of epitope G40-R43 on β2GPI is highly variable between commercial anti-β2GPI assays. As a consequence, patients can be falsely assigned negative in assays characterized by a reduced exposure of G40-R43.

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Section: Discussionmentioning

confidence: 99%

“…A major problem within APS is the variability between different commercially available assays [2], [12], [13], [14]. In other words, a sample assigned positive in one test does not automatically test positive in the same type of assay from a different manufacturer.…”

Section: Introductionmentioning

confidence: 99%

Variability in Exposure of Epitope G40-R43 of Domain I in Commercial Anti-Beta2-Glycoprotein I IgG ELISAs

et al. 2013

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“…There is a large variety of assays assessing aPL and despite consensus guidelines, some issues remain unanswered [2]. Factors that contribute to result variability include pre-, post-and analytical conditions, calibration and assay-specific issues [3].…”

Section: Introductionmentioning

confidence: 99%

Testing for Antiphospholipid antibodies with Solid Phase Assays: guidance from the SSC of the ISTH

Devreese

Pierangeli

Laat

et al. 2014

Journal of Thrombosis and Haemostasis

189

267

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“…Issues such as antibody heterogeneity, between‐reagent and between‐platform variability, and differences in raw data manipulation and interpretation, conspire to make standardization an elusive goal. Consequently, gold standard assays and reference plasmas are not yet established 4, 5. While aCL and aβ2GPI assays can be calibrated to generate quantitative results in semi‐arbitrary units to aid interpretation, a medley of phospholipid‐dependent coagulation assays are employed for LA detection and the presence of LA is inferred or excluded from the result patterns obtained.…”

Section: Introductionmentioning

confidence: 99%

Lupus anticoagulant mixing tests for multiple reagents are more sensitive if interpreted with a mixing test‐specific cut‐off than index of circulating anticoagulant

Kumano

Moore

2018

Research and Practice in Thrombosis and Haemostasis

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Essentials Various approaches are available for interpreting lupus anticoagulant mixing tests.Mixing test specific cut‐off (MTC) was compared with index of circulating anticoagulant (ICA).MTC was superior to ICA in detecting inhibition by lupus anticoagulant (LA) in multiple reagents.Detection rates of LA can be improved by the method to interpret the results. BackgroundLupus anticoagulant (LA) is classified in the antibody family that is recognized as antiphospholipid antibodies. Guidelines for LA detection recommend mixing test interpretation with either a mixing test specific cut‐off (MTC) or index of circulating anticoagulant (ICA). We previously evidenced that MTC was superior to ICA in detecting the in vitro inhibition of LA with a single dilute APTT (activated partial thromboplastin time) and dRVVT (diluted Russell's viper venom time) pairing.ObjectivesThe objective in the present study was to compare the LA diagnostic effectiveness of MTC and ICA by multiple APTT and dRVVT reagents.MethodsOne hundred‐five samples from non‐anticoagulated patients positive for LA in the dilute APTT (dAPTT) and dRVVT reagent pairing employed for diagnostic examination were performed by undiluted and in a 1:1 mix with normal pooled plasma with four additional APTT reagents and another dRVVT reagent (dRVVT B).ResultsFrequencies of MTC and ICA positivity were determined from samples LA positive in undiluted plasma. MTC positivity in mixing test were 63%, 77%, 80%, 84%, 46%, 81%, and 72% in 4 APTT, dAPTT and 2 dRVVT, respectively. ICA positivity were 47%, 67%, 58%, 54%, 42%, 47%, and 29%, respectively. There were no samples of ICA‐positive/MTC‐negative with any reagent.ConclusionsThe data indicate that MTC is superior to ICA for LA detection in mixing tests in multiple reagents and reagent types. Although mixing tests may make weak LA samples appear negative, the efficacy of LA detection can be improved by the method to interpret the results.

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Standardization of antiphospholipid antibody assays. Where do we stand?

Cited by 70 publications

References 23 publications

Variability in Exposure of Epitope G40-R43 of Domain I in Commercial Anti-Beta2-Glycoprotein I IgG ELISAs

Variability in Exposure of Epitope G40-R43 of Domain I in Commercial Anti-Beta2-Glycoprotein I IgG ELISAs

Testing for Antiphospholipid antibodies with Solid Phase Assays: guidance from the SSC of the ISTH

Lupus anticoagulant mixing tests for multiple reagents are more sensitive if interpreted with a mixing test‐specific cut‐off than index of circulating anticoagulant

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