Lupus Anticoagulants/Phospholipid-Dependent-Antibodies

Thursday June 29, 2006
Oslo Kongressenter, Norway

Chairman: Ph. G. de Groot (The Netherlands)
Co-chairs: M. Galli, Italy;; S. Machin (UK); T Ortel (USA), J. V. Pengo (Italy); H. Rand (USA) ; G. Reber (Switzerland), R. Roubey (USA)

Genetics

Gene expression profiles are capable of identifying subtle distinctions that define important clinical phenotypes. Dr. Ortel ( USA ) and coworkers have recently demonstrated that gene expression patterns can distinguish patients with antiphospholipid syndrome (APS) from non-APS patients with venous thromboembolism as well as from asymptomatic individuals with elevated antiphospholipid antibody levels. Translating microarray data into a useful clinical laboratory test requires identifying the smallest number of genes that provide sufficient discriminatory power and using quantitative RT-PCR-based analyses to analyze these genes.

Coagulation

Dr de Groot (the Netherlands ) presented the results of a multi centre study on the predictive value of an LA assay that was only dependent on anti-beta2GPI antibodies for the clinical manifestations observed in APS. 325 patients positive for LA (214 patients with hrombotic complications and 72 patients with pregnancy morbidity) from 6 hospitals were included. The major conclusion was that a LA dependent on anti-beta2GPI antibodies correlates better with thrombotic complications compared to a normal LA (OD = 3.3) but that the assay was not solid enough to be performed on a diagnostic laboratory of a general hospital. A positive LA assay combined with a positive anti-beta2GPI ELISA also results in an improved detection of patients at risk for thrombosis (OR 2.5) and this combination was recommended.

Dr. Haywarth ( Canada ) discussed the implantation of the SSC recommendations in diagnostic laboratories 15 years after the publication. NASCOLA and ECAT laboratories were surveyed to determine if their LA testing practices conformed to 1995 ISTH SSC recommendations. High conformity was seen in following the recommendations to do two or more LA tests, based on different principles, and at least one test to confirm phospholipid dependence. However, many sites did not perform mixing studies to demonstrate an inhibitor and only a few did investigations to exclude a specific factor deficiency or an inhibitor. These data suggest that recommendations and/or practices for LA testing need updating.

Dr. Ortel ( USA ) discussed Point-of-Care INR Monitoring in Patients with APS. A subset of patients with antiphospholipid syndrome (APS) has antibodies that appear to interfere with determination of the PT with certain thromboplastins, complicating monitoring warfarin therapy with the INR. Point-of-Care INR monitors are being increasingly used for the management of patients on chronic warfarin therapy. As with plasma-based INR measurements, certain patients with APS have unreliable INR measurements using point-of-care meters. Patients with APS who are being considered for INR monitoring with a point-of-care meter should have correlations performed with the main laboratory plasma-based INR, with discordant results being further evaluated with additional assays prior to using a specific meter with a given patient.

ELISAs

Dr Pierangeli ( USA ) gave an overview of the various tests used in the diagnosis of APS and on the recommendations of the revised classification Sapporo for diagnosis of APS was first presented. There was emphasis on current and on-going problems and challenges with the various tests, recognizing that one of the major shortcomings of the aCL ELISA is the number of “false positive” results in patients with infectious and other autoimmune diseases. In an effort to address some of those issues, samples from 56 APS patients (classified according to the Sapporo criteria), from 206 patients with infectious diseases and various autoimmune disorders, and from 150 healthy controls were tested in a blind fashion in various centers utilizing: an anti- b 2 GPI, an anti-PT ELISAs, or an aCL (in-house) ELISAs, and a commercial kits for anti- b 2 GPI ELISA kit (INOVA Diagnostics, Inc.) and aPL ELISA kit (APhL ELISA, Louisville APL Diagnostics, Inc.). The tests were considered positive when results were above the cut-off points established for each assay for either IgG and/or IgM isotypes. Receiver Operating Curves (ROC) were created to compare the areas under the curve for the various tests. The nominal cut-offs for statistical significance was set at 0.05. All statistical tests were two sided. Sensitivities and specificities were determined. ROC curves showed that the APhL ELISA, that utilizes a mixture of phospholipids and b 2 GPI instead of CL, showed the best predictive value, followed in decreasing order by the anti- b 2 GPI (in-house), the aCL (in-house), the anti- b 2 GPI (INOVA) and the aPT (in house). Although the aPT assay showed a good specificity, the sensitivity was 24.07 % and was not found positive in any APS sample in the absence of a positive aCL, APhL or anti- b 2 GPI test. Either aCL and/or APhL and /or anti- b 2 GPI tests were found positive in all APS samples. This study validates the recommendations of the recently revised classification criteria for APS with respect to serological tests recommended for the diagnosis of APS (Participating centers and collaborators. Istituto Auxologico Italiano, Milan , Italy . (Prof. Pier Luigi Meroni and Maria Orietta Borghi, Department of Ob-Gyn. Univ. of Utah , Salt Lake City (Dr. D. Ware Branch and Jurhee Rice), Department of Neurology. Univ. of Texas , Health Sciences Center San Antonio . (Dr. Robin Brey and Pat Padilla), Antiphospholipid Standardization Laboratory. Morehouse School of Medicine. Atlanta,GA. (Dr. Silvia S. Pierangeli, Veronica Henderson, Dr. Hector R. Pierangeli), Clinical Research Center, Morehouse School of Medicine. Atlanta, GA. (Dr. Alexander Quarshie))

Relation between serological and clinical manifestations

Dr. Pengo ( Italy ) discussed the presence of different ype of antiphospholipid antibodies and the clinical course of patients with primary obstetric APS patients. In primary APS with pregnancy morbidity in classification category I, quite different groups of patients may be identified on the basis of laboratory tests. Triple positivity and/or a history of thromboembolism predict new TE events and new unsuccessful pregnancies.

Dr Galli ( Italy ) analysed the prevalence and clinical significance of various antiphospholipid antibodies in 112 patients enrolled in the the WAPS (Warfarin in the AntiPhospholipid Syndrome) study. Anti-beta2-glycoprotein I antibodies were significantly associated with all the major endpoints of the syndrome (arterial and venous thrombosis and obstetric complications), thus confirming the usefulness of their inclusion among the laboratory criteria of the APS. Antibodies to prothrombin, protein S and annexin A V appeared associated with some selected clinical endpoints. The measurement of IgG but not IgM antibodies appeared clinically useful. The generation of laboratory profiles (by combining two or more clotting or ELISA positive tests) did not really improve the identification of patients at risk of thrombosis.

Dr. Pierangeli (USA), also on behalf of dr Roubey (USA) reported on the Antiphospholipid Syndrome Collaborative Registry (APSCORE): What Can we learn from this registry?
The Antiphospholipid Syndrome Collaborative Registry (APSCORE) is a national, NIH-funded, multicenter disease registry in the United States .  The registry is designed to support a broad range of research projects involving the etiology, pathophysiology, diagnosis and treatment of the antiphospholipid syndrome (APS).  Over the past 4 years, APSCORE has enrolled approximately 900 subjects including both patients with APS and asymptomatic individuals with antiphospholipid antibodies (aPL).  Patients are followed every 2 years.  The registry includes a detailed clinical database, core laboratory data, and a tissue repository with plasma, serum, and genomic DNA specimens.  Characteristics of the APSCORE cohort will be reviewed, including the correlation of historical aPL results with core laboratory studies, and correlation of core laboratory data at enrolment and at two-year follow-up.  Registry resources (data and specimens) have been made available to the research community and 12 research projects are currently supported or under review.  Mechanisms for obtaining APSCORE resources will be reviewed.

Dr. Boffa ( France ) presented a registry of children born to mothers with the antiphospholipid syndrome. The aim of this register is to study the immunological status of infants born to mothers with APS from birth to 5 years and to evaluate their clinical symptoms and neuro-developmental evolution during this period in relationship with the maternal disease. Up to now 75 couples “mother/child” were included. A level around 18% of prematurity and of intra-uterine growth retardation was observed. Few neo-antibodies appeared at birth. Two out of the 20 infants followed up to 2 years showed abnormal behaviour (1 confirmed autism). This addresses the question: are infants born to mothers with APS more susceptible to develop abnormal behaviour?