Efforts to Harmonize ELISA and Non-ELISA Anticardiolipin and Anti-β2-glycoprotein-I Levels Based on ISTH SSC LA/aPL and APS ACTION International Multicenter Cohorts

Arne Vandevelde¹, Pierluigi Meroni², Hannah Cohen³, Danieli Andrade⁴, Olga Amengual⁵, TATSUYA ATSUMI⁵, Angela Tincani⁶, H Michael Belmont⁷, Maria Borghi⁸, David Branch⁹, Ricard Cervera¹⁰, Guilherme Ramires de Jesús¹¹, Paul Fortin¹², Jean-Christophe Gris¹³, Claudia Grossi⁸, Jason Knight¹⁴, Gary W. Moore¹⁵, Jacek Musiał¹⁶, Michelle Petri¹⁷, Esther Rodriguez-Almaraz¹⁸, Diana Paredes-Ruiz¹⁹, Robert Roubey²⁰, Anne Tebo²¹, Maria Tektonidou²², Denis WAHL²³, Stéphane Zuily²³, Rohan Willis²⁴, Vittorio Pengo²⁵, Maria Laura Bertolaccini²⁶, Doruk Erkan²⁷ and Katrien Devreese¹, ¹Department of Diagnostic Sciences, Ghent University and Coagulation Laboratory, Ghent University Hospital, Ghent, Belgium, ²IRCCS Istituto Auxologico Italiano 100%, Cusano Milanino, Milan, Milan, Italy, ³University College London Hospitals NHS Foundation Trust, London, United Kingdom, ⁴University of São Paulo, São Paulo, SP, Brazil, ⁵Department of Rheumatology, Endocrinology and Nephrology, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Japan, ⁶ASST Spedali Civili-University of Brescia, Brescia, Italy, ⁷NYU School of Medicine, New York, NY, ⁸Immunorheumatology research laboratory, IRCCS Istituto Auxologico, Milan, Italy, ⁹University of Utah and Intermountain Healthcare, Salt Lake City, UT, ¹⁰Hospital Clinic de Barcelona, Barcelona, Spain, ¹¹Universidade do Estado do Rio de Janeiro, Rio De Janeiro, Brazil, ¹²Centre ARThrite - CHU de Québec - Université Laval, Quebec, QC, Canada, ¹³Department of Hematology, CHU Nîmes, Univ Montpellier, Nîmes, France and Department of Hematology, Faculty of Pharmaceutical and Biological Sciences, Montpellier University, France and UMR UA11 INSERM IDESP - Montpellier University, France and Department of Obstetrics and Gynecology, I.M. Sechenov First Moscow State Medical University, Moscow, Russia, ¹⁴University of Michigan, Ann Arbor, MI, ¹⁵Specialist Haemostasis Unit, Addenbrooke's Hospital, Cambridge, United Kingdom and Department of Natural Sciences, Middlesex University, London, United Kingdom, ¹⁶Department of Internal Medicine, Jagiellonian University Medical College, Kraków, Poland, ¹⁷Johns Hopkins University School of Medicine, Timonium, MD, ¹⁸Hospital Universitario 12 de Octubre, Madrid, Spain, ¹⁹Autoimmune Diseases Research Unit. Biocruces Bizkaia Health Research Institute, Baracaldo, Spain, ²⁰Division of Rheumatology, Allergy, and Immunology, University of North Carolina, Chapel Hill, NC, ²¹Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, ²²National and Kapodistrian University of Athens, Athens, Greece, ²³Lorraine University, Nancy, France, ²⁴University of Texas Medical Branch, Galveston, TX, ²⁵Thrombosis Research Laboratory, Department of Cardio-Thoracic-Vascular Sciences and Public Health, University of Padova, Padova, Italy, ²⁶King's College London, London, United Kingdom, ²⁷Hospital for Special Surgery, New York, NY

Meeting: ACR Convergence 2024

Keywords: antiphospholipid syndrome

Session Information

Date: Saturday, November 16, 2024

Title: Antiphospholipid Syndrome Poster

Session Type: Poster Session A

Session Time: 10:30AM-12:30PM

Background/Purpose: Correlation of numerical values between the low, moderate, and high (L, M,H) levels of enzyme-linked immunosorbent assay (ELISA) and non-ELISA platforms for anticardiolipin antibody (aCL) and anti-β2-glycoprotein-I antibody (aβ2GPI) IgG/IgM varies substantially. For instance, based on the International Society on Thrombosis and Haemostasis Scientific and Standardization Committee on Lupus anticoagulant/Antiphospholipid antibodies (ISTH-SSC LA/aPL) Subcommittee multicenter study, an IgG aCL value measured by chemiluminescent immunoassay (CLIA) was up to 5 times higher compared to the ELISA value of 40–80 U (1). Based on this study, L, M, H thresholds for different ELISA and non-ELISA aCL/aβ2GPI tests were previously proposed (2). We aim to determine whether these thresholds can be applied to another independent cohort (AntiPhospholipid Syndrome Alliance For Clinical Trials and InternatiOnal Networking [APS ACTION] registry).

Methods: Patients fulfilling the Revised Sapporo APS Classification Criteria were identified from two independent cohorts: ISTH SSC LA/aPL Multicenter Cohort (Group A) and APS ACTION Registry (Group B). Samples were analyzed in the ISTH-SSC LA/aPL core laboratory (group A) and in APS ACTION validated core laboratories (group B), using QUANTA Lite ELISA (Werfen), AcuStar CLIA (Werfen) and Phadia EliA fluorescence enzyme immunoassay (FEIA) (Thermo Fisher). Thresholds for L-M-H positive aPL levels previously determined by receiver operating characteristic (ROC) analysis correspond to three ranges (Manufacturer’s cutoff – 97.5% specificity, 97.5% – 99.5% specificity, and ≥99.5% specificity) (Table 1) [1]. The frequency of aCL/aβ2GPI positivity and the distribution in L-M-H levels were compared between the two cohorts. Statistical analyses (box-and-whisker plots, Mann-Whitney U-testing, comparison of proportions and Chi-Square statistics) were done with Python and MedCalc.

Results: Based on the analysis of 381 Group A (ISTH) and 445 Group B (APS ACTION) patients, group B patients were more frequently positive for aCL/aβ2GPI, compared to Group A (Table 2) but with similar aPL levels except for aβ2GPI IgG (Figure 1). aCL and aβ2GPI IgG/IgM results had similar proportions within the L-M-H semiquantitative ranges in the two patient cohorts (Table 2).

Conclusion: In APS patients, the distribution of positive aCL and aβ2GPI IgG/IgM categorized into L-M-H levels, measured by ELISA, CLIA and FEIA, was similar between two independent patient cohorts. These results suggest that thresholds for semiquantitative interpretation of aCL and aβ2GPI results could apply across laboratories and APS patient populations.

[1] Vandevelde, A., et al. J Thromb Haemost, 2022, doi: 10.1111/jth.15585
[2] Vandevelde, A., et al. J Thromb Haemost, 2024, doi: 10.1016/j.jtha.2024.04.016

Table 1. Threshold levels for semiquantitative interpretation of aCL and aβ2GPI IgG/IgM with ELISA, CLIA, and FEIA. N/A = Not applicable.

Table 2. Number and proportion of positive samples for aCL and aβ2GPI IgG/IgM, subdivided per semiquantitative level range. ELISA, CLIA, and FEIA results are compared between APS ACTION and ISTH-SSC LA/aPL APS cohorts.
P-values derived from Chi-Square tests; * denotes significant different proportion positives (p<0.05); N/A = Not applicable.

Figure 1. Combined dot and box-and-whisker plots comparing distribution of positive aCL and aβ2GPI IgG/IgM levels between APS ACTION and ISTH-SSC LA/aPL cohorts. A) CLIA, B) ELISA, and C) FEIA results.
P-values derived from Mann-Whitney U tests; black and red dotted lines represent respective moderate and high level thresholds. For FEIA, the y-axis has a logarithmic scale.

Disclosures: A. Vandevelde: None; P. Meroni: None; H. Cohen: argenx, 1, GlaxoSmithKlein(GSK), 6, Roche, 1, Technoclone (paid to Univ Coll London Hosp Charity), 6, UCB (paid to Univ College London Hosp Charity), 2; D. Andrade: None; O. Amengual: None; T. ATSUMI: None; A. Tincani: None; H. Belmont: Alexion, 1, Aurinia, 6; M. Borghi: None; D. Branch: UCB Pharma Inc, 5; R. Cervera: None; G. Ramires de Jesús: None; P. Fortin: AstraZeneca, 2, 6, GlaxoSmithKlein(GSK), 2, 6, Moderna, 2; J. Gris: None; C. Grossi: None; J. Knight: ArgenX, 1, Visterra/Otsuka, 1, 2; G. Moore: Technoclone, 2; J. Musiał: None; M. Petri: Amgen, 2, AnaptysBio, 2, Annexon Bio, 2, Arthros-FocusMedEd, 6, AstraZeneca, 2, 5, Atara Biosciences, 2, Aurinia, 5, 6, Autolus, 2, Avoro Ventures, 2, Biocryst, 2, Boxer Capital, 2, Cabaletto Bio, 2, Caribou Biosciences, 2, CTI, 1, CVS Health, 1, Eli Lilly, 2, 5, Emergent Biosolutions, 1, Ermiium, 2, Escient Pharmaceuticals, 2, Exagen, 5, Exo Therapeutics, 2, Gentibio, 2, GlaxoSmithKlein(GSK), 2, 5, iCell Gene Therapeutics, 2, Innovaderm Research, 2, IQVIA, 1, Janssen, 5, Kira Pharmaceuticals, 2, Merck/EMD Serono, 1, Nexstone Immunology, 2, Nimbus Lakshmi, 2, Novartis, 2, PPD Development, 2, Precision Biosciences, 2, Proviant, 2, Regeneron Pharmaceuticals, 2, Sanofi, 2, Seismic Therapeutic, 2, Senti Bioscienes, 2, Sinomab Biosciences, 2, Takeda, 2, Tenet Medicines Inc, 2, TG Therapeutics, 2, UCB, 2, Vertex Pharmaceuticals, 2, Worldwide Clinical Trials, 1, Zydus, 2; E. Rodriguez-Almaraz: None; D. Paredes-Ruiz: None; R. Roubey: None; A. Tebo: Euroimmun US, 6; M. Tektonidou: None; D. WAHL: None; S. Zuily: None; R. Willis: Louisville APL Diagnostics Inc, 2, 8; V. Pengo: None; M. Bertolaccini: None; D. Erkan: ACR, 5, APS ACTION, 4, Argenx, 1, Cadrenal, 2, Chugai, 1, EULAR, 5, Exagen, 5, GlaxoSmithKlein(GSK), 2, 5, 6, Kyverna, 1, NIH, 5, Otsuka/Visterra, 1, Up-To-Date, 9; K. Devreese: None.

To cite this abstract in AMA style:

Vandevelde A, Meroni P, Cohen H, Andrade D, Amengual O, ATSUMI T, Tincani A, Belmont H, Borghi M, Branch D, Cervera R, Ramires de Jesús G, Fortin P, Gris J, Grossi C, Knight J, Moore G, Musiał J, Petri M, Rodriguez-Almaraz E, Paredes-Ruiz D, Roubey R, Tebo A, Tektonidou M, WAHL D, Zuily S, Willis R, Pengo V, Bertolaccini M, Erkan D, Devreese K. Efforts to Harmonize ELISA and Non-ELISA Anticardiolipin and Anti-β2-glycoprotein-I Levels Based on ISTH SSC LA/aPL and APS ACTION International Multicenter Cohorts [abstract]. Arthritis Rheumatol. 2024; 76 (suppl 9). https://acrabstracts.org/abstract/efforts-to-harmonize-elisa-and-non-elisa-anticardiolipin-and-anti-%ce%b22-glycoprotein-i-levels-based-on-isth-ssc-la-apl-and-aps-action-international-multicenter-cohorts/. Accessed .

« Back to ACR Convergence 2024

ACR Meeting Abstracts - https://acrabstracts.org/abstract/efforts-to-harmonize-elisa-and-non-elisa-anticardiolipin-and-anti-%ce%b22-glycoprotein-i-levels-based-on-isth-ssc-la-apl-and-aps-action-international-multicenter-cohorts/