aβ2GPI Antibodies Research Articles

Establishment of cutoff values for anti-β2 glycoprotein I antibodies in women of reproductive age in Southwest China

Antiphospholipid syndrome (APS) is an autoimmune disorder characterized by vascular thrombosis and obstetric morbidity, with accurate laboratory examination of antiphospholipid antibodies (aPLs) being crucial for diagnosis. This study focused on anti-β2 glycoprotein I (aβ2GPI) antibodies and aimed to establish the first population-based cutoff values for aβ2GPI IgA/IgM/IgG antibodies in non-pregnant women of reproductive age in Southwest China. The study cohort comprised 181 healthy women of reproductive age for study. Blood samples were collected on an early morning fast. Anti-β2GPI antibodies including IgA, IgM and IgG were measured in serum using the HOB® BioCLIA kit. According to the Clinical and Laboratory Standards Institute (CLSI) guidelines, the study used non-parametric percentile methods to calculate the 95th, 97.5th, and 99th percentiles cutoff values for aβ2GPI IgA/IgM/IgG antibodies, along with corresponding 90% confidence intervals (CI), while excluding outliers. A total of 168 independent samples were collected for verification, including 85 samples from healthy subjects and 83 samples from APS patients, in order to evaluate the analytical performance of the obtained cutoff values. The 99th percentile cutoff values were 3.36 RU/mL for aβ2GPI IgA, 27.54 RU/mL for aβ2GPI IgM and 1.81 RU/mL for aβ2GPI IgG, which indicated that the levels of aβ2GPI IgM antibodies were generally higher compared to those of IgA and IgG antibodies. Our established reference range was confirmed to be successful in validating the detected values of aβ2GPI antibodies in all healthy controls. With the 99th percentile cutoff value, the sensitivity was 14.46% for aβ2GPI IgA, 22.89% for aβ2GPI IgG, and 9.64% for aβ2GPI IgM in APS patients. This study established population-based cutoff values that are applicable to the local population for the accurate laboratory examination of aβ2GPI antibodies in non-pregnant women of reproductive age. The study also recommends paying more attention to IgM positivity in women of reproductive age.

The clinical relevance of different antiphospholipid antibody profiles in pediatric rheumatology patients

BackgroundThe clinical relevance of different antiphospholipid antibody (aPL) profiles, including low level anticardiolipin (aCL) and anti-β2-glycoprotein-I (aβ2GPI) antibodies, is ill-defined in the pediatric population. Our purpose is to describe the demographic, clinical, and laboratory characteristics of aPL positive pediatric patients based on different aPL profiles.FindingsIn this single center retrospective cohort study, based on the screening of our pediatric (age ≤ 18) rheumatology electronic medical records (2016–2022), we identified patients who had at least one “positive” aPL (lupus anticoagulant [LA], aCL IgG/M, or aβ2GPI IgG/M) result. Patients were grouped into high- (LA positive and/or aCL/aβ2GPI IgG/M > 40U [ELISA]) and low-risk (LA negative and aCL/aβ2GPI IgG/M 20-39U) aPL profiles; those with persistently positive aPL were descriptively analyzed for demographic and clinical characteristics. Of 57 included patients, 34 (59%) had initial high- and 23 (40%) had initial low-risk profiles. Based on subsequent aPL results available in 42/57 (74%) patients, 25/27 (93%) in the high-, and 7/15 (47%) in the low-risk groups remained still positive. Of these 32 patients with persistently positive aPL, moderate-to-large vessel or microvascular thrombosis occurred in nine (28%) patients with high-risk and in none with low-risk aPL profiles; non-thrombotic aPL-related manifestations were reported in 15 (47%) patients with persistent aPL positivity.ConclusionAn initial high-risk aPL profile was persistent in approximately 90% of our cohort, a third of whom had thrombosis, and half had non-thrombotic aPL manifestations. Our results underscore the need for a large-scale effort to better characterize aPL-related manifestations in pediatric patients with persistent high-risk aPL-profiles.

Nailfold capillaroscopy abnormalities and pulmonary hypertension in mixed connective tissue disease and systemic sclerosis patients.

Pulmonary arterial hypertension (PAH) represents an important vascular complication of mixed connective tissue disease (MCTD) and systemic sclerosis (SSc). Microvascular involvement in these diseases can be investigated by means of nailfold capillaroscopy (NFC). Microvascular involvement detected in the nailfold bed is the mirror of the microvascular damage occurring in the entire body, further indicating the involvement of the target organs. The aim of this study was to evaluate the microvascular involvement in MCTD patients with or without PAH, compared to that found in SSc patients with or without PAH. This cross-sectional study was performed in the Department of Internal Medicine and Department of Rheumatology, Timișoara, Romania, during the time period between January 2017 and December 2022, on a group of 26 patients with MCTD and 26 SSc patients. Antinuclear antibodies, anti-U1-RNP, anti-Scl 70, anti-centromere, anti-cardiolipin antibodies (aCL) (IgM, IgG), anti-β2-glycoprotein I (aβ2GPI) (IgM, IgG) antibodies, and lupus anticoagulant (LAC) were determined in both the groups. PAH was evaluated through cardiac ultrasonography, determining the sPAP (systolic pulmonary artery pressure). Nailfold capillaroscopy was performed using a USB Digital Microscope and 2.0-megapixel digital camera recording capillaries density, giant capillaries, enlarged capillaries, capillaries hemorrhages, avascular areas, ramified/bushy capillaries scores. Data were recorded and presented as mean ± standard deviation. Statistical analyses were performed using the Student's t-test, ANOVA test, and Pearson's correlation. Differences were considered statistically significant if p-value < 0.05. Among the MCTD patients, PAH was identified in 12 patients (46.15%), while among the SSc patients PAH was identified in 14 patients (53.84%). Development of PAH in MCTD patients was associated with lower capillaries density (p-value < 0.00001), higher scores of giant capillaries, ramified/bushy capillaries, and capillary hemorrhages (p-value < 0.00001, for each of them). Anti-U1-RNP, aCL, aβ2GPI antibodies and LAC were also found to be involved in PAH-associated MCTD development. Unlike MCTD patients, SSc patients with PAH presented with lower capillaries density and ramified/bushy capillaries scores (p-value < 0.05). The MCTD patients who presented significant NFC abnormalities (especially active and late scleroderma-like capillaroscopic pattern) are prone to PAH development. Capillary density reduction is the most important factor associated with the occurrence of PAH. Differences in NFC findings (especially capillary density and ramified/bushy capillaries) were detected among patients with MCTD and SSc having PAH.

Variable Performance of Lupus Anticoagulant Testing: The Australasian/Asia-Pacific Experience.

Lupus anticoagulant (LA) is one of three tests identified as laboratory criteria for definite antiphospholipid syndrome (APS). The other two tests are anticardiolipin antibody (aCL) and anti-β2-glycoprotein I (aβ2GPI) antibody. The presence of LA is assessed using clot-based tests, while the presence of aCL and aβ2GPI is assessed by immunological assays. Since no test can be considered 100% sensitive or specific for LA, current guidelines recommend using two different clot-based assays reflecting different principles, with the dilute Russell viper venom time (dRVVT) and activated partial thromboplastin time (aPTT) recommended. Initially, LA-sensitive reagents are used to screen for LA, and then, in "screen-positive" samples, LA-"insensitive" reagents are used to confirm LA. Because LA assays are based on clot detection, anything that can interfere with fibrin clot development may affect test results. In particular, in addition to LA, the tests are also sensitive to the presence of a wide range of clinical anticoagulants, reflecting preanalytical issues for testing. We provide updated findings for LA testing in our geographic region, using recent data from the Royal College of Pathologists of Australasia Quality Assurance Programs, an international external quality assessment program with approximately 120 participants. Data show a wide variety of assays in use, especially for aPTT testing, and variable outcomes in reported numerical values with these assays when assessing proficiency samples. dRVVT testing mostly comprised reagents from three main manufacturing suppliers, which also showed differences in numerical values for the same homogeneous tested samples. Nevertheless, despite the use of different test reagents and processes, >98% of participants correctly identified LA-negative samples as LA-negative and LA-positive samples as LA positive. We hope our findings, reflecting on the heterogeneity of test processes and test data, help improve diagnostic testing for LA in the future.

B-093 Evaluation of the Association of Non-criteria Antiphospholipid Antibodies with the Presence of Lupus Anticoagulant

Abstract Backrground Laboratory diagnosis of the antiphospholipid antibody syndrome (APS) requires evidence ofpersistently positive lupus anticoagulant (LAC), detected using clot-based assays and/or thepresence of high-titer serum anti-cardiolipin (aCL) and/or anti-beta-2 glycoprotein-1 (aB2GPI)antibodies, measured by semi-quantitative solid-phase immunoassays. Several non-criteria anti-phospholipid antibodies (NC-APLA) have been proposed as candidates for APS diagnosis:phosphatidyl-serine/ prothrombin (aPS/PT; IgM and IgG isotypes), anti-phosphatidyl serine (aPS;IgM and IgG), anti-prothrombin (aPT-IgG). However, their diagnostic relevance in routine APSevaluation is still unclear. The objectives of this study were 1) to determine the prevalence andassociation of NC-APLA in relation to LAC, aCL and aB2GPI antibodies’ positivity,independently and in combination and, 2) to assess the ability of NC-APLA to predict LACactivity, as an indirect measure of their function. Methods Results from 492 patients submitted for antiphospholipid antibody (APLA) panel or standaloneserology testing between January 2016 to January 2023 were retrieved in accordance withinstitutional guidelines. Patients were grouped according to LAC status and serology positivity(using manufacturer-suggested cutoff) into three groups: Single-positives (SP) for LAC, aCL oraB2GPI; Double-positives (DP) for aCL and aB2GPI; Triple-positives (TP) for LAC, aCL andaB2GPI. NC-ALPA titers were compared between LAC-positive and negative patients. Statisticalsignificance was established using unpaired Student’s t-test. Receiver operating curve (ROC)analysis was employed to assess the ability of NC-APLA to predict LAC status. Results Out of the total 492 patients, 1.8% (9/492) were TP, 2.4% (12/492) were DP and 24.7% (122/492)were SP. All NC-APLA titers were significantly higher in TP than in SP patients (P &amp;lt; 0.001).aPS/PT IgG (Mean: 76.3 vs 12.8 Units) and aPS IgG (Mean: 64.8 vs 5.5 GPS) antibodies weresignificantly higher in TP than DP patients (P = 0.008 and &amp;lt;0.0001, respectively). aPS/PT IgM(Mean: 62.5 vs 19.4 Units) and aPS IgM titers (Mean 31.9 vs 7.7 MPS) were significantly higherin DP compared to SP patients (P &amp;lt; 0.0001). When classified by LAC status, 40 patients werepositive and 452 were negative. Levels of all NC-APLA antibody titers (P &amp;lt; 0.0001) followed byaCL (Mean IgG 21.9 vs 7.8 GPL; IgM 20 vs 12.6 MPL; P &amp;lt; 0.01) and aB2GPI (Mean IgG 20.1 vs 4.9 SGU; IgM 13.8 vs 7.6 SMU, P &amp;lt; 0.001) antibodies were significantly higher in LAC-positivepatients compared to the LAC-negative individuals. ROC analyses based on the LAC statusresulted in the highest area under the curve (AUC, 95% CI) for aPS/PT IgM (0.72, 0.62 to 0.81)Private Information and aPS/PT IgG (0.74, 0.65 to 0.83) antibodies relative to aCL (IgM:0.53, 0.43 to 0.64; IgG:0.66, 0.56 to 0.77) or aB2GPI (IgM:0.5, 0.51 to 0.72 and IgG:0.6, 0.51 to 0.72) antibodies; aPS IgMand aPT IgG displayed similar performances (0.65, 0.54 to 0.75 and 0.66, 0.57 to 0.74,respectively). Whereas aPS IgG was of lower AUC (0.58, 0.48 to 0.68). Conclusion Our data demonstrated that at high titers, NC-APLA, display increased association with LACpositivity in comparison to aCL or aB2GPI antibody levels. Particularly, aPS/PT antibodiesdisplayed the superior ability to determine the LAC presence.Private Information

Anti-Phosphatidylserine, Anti-Prothrombin, and Anti-Annexin V Autoantibodies in Antiphospholipid Syndrome: A Real-Life Study.

The antiphospholipid antibodies (aPL) increase the risk of developing thrombotic events and may coexist with a variety of autoimmune diseases. They can be detected chronically or temporarily in patients with infectious diseases, during drug therapy, or in cases of cancer. A thrombotic event with aPL detection is known as antiphospholipid syndrome (APS) and the diagnostic criteria include the presence of lupus anticoagulant (LA), anticardiolipin (aCL) and β2-glycoprotein-1(aβ2GPI) antibodies. Other autoantigens recognized in APS are phosphatidylserine (aPS), prothrombin (aPT) and Annexin-5 (aA5). This real life study aimed to explore the connections between laboratory criteria and the prevalence of "non-criteria aPL" in APS. This study followed 300 patients with thrombosis and employed two phospholipid sensitivity assays for LA detection, chemiluminescence assays for aCL and aβ2GPI and enzyme-linked immunoassays for aPS, aPT and aA5. A significant association was found between aPS and aCL (r = 0.76) as well as aβ2GPI (r = 0.77), while the association with LA was less significant (r = 0.33). The results of the aPT and aA5 test did not correlate with criteria-antiphospholipid antibodies (r < 0.30). Since the risk of thrombotic complications increases with the intensity and the number of positive autoantibodies, measuring aPT and aA5 autoantibodies may be useful, particularly in aCL/aβ2GPI-negative patients or in cases of isolated LA positivity.

Antiphospholipid antibodies in pulmonary embolism treated with direct oral anticoagulants: Prevalence data from unselected consecutive patients

BackgroundDirect oral anticoagulants (DOACs) are the first-choice treatment option for the prevention of the recurrence of venous thrombosis in patients with pulmonary embolism (PE); however, their effect in patients with antiphospholipid syndrome (APS) is challenged. Therefore, the prevalence of antiphospholipid autoantibodies in patients with PE is noteworthy. ObjectivesTo determine the prevalence of unselected patients presenting with PE who meet the criteria for APS based on elevated levels of anticardiolipin (aCL) and anti-β2-glycoprotein I (aβ2GPI) antibodies. MethodsConsecutive patients with PE, in whom DOACs were primarily initiated, were tested for aCL and aβ2GPI. If the levels were elevated, the tests were repeated after 12 weeks for APS diagnosis. Laboratory results and patient characteristics were retrospectively collected from a laboratory information system and electronic patient journal entries over a 2-year period. ResultsThe prevalence of APS based on consistently elevated levels of aCL or aβ2GPI was 3.7% (10 of 267 patients). Three patients were double positive. In 11 out of 21 patients (52%) with initially elevated values, the levels of the antibodies normalized after 12 weeks. The patient characteristics were largely similar in those with APS and those without APS; however, patients with APS tended to be older and more likely to receive antithrombotic treatment at the time of PE. ConclusionWe found a relatively low prevalence of APS based on aCL or aβ2GPI. The high rate of normalized levels of the antibodies after 12 weeks reaffirms the need for repeated tests for APS diagnosis. Older patients more frequently met the criteria for APS. Determining the effectiveness of DOACs in non–triple-positive patients with APS following venous thromboembolism is important to further determine the feasibility of unselected tests in patients with PE.

Anticardiolipin and/or anti-β2-glycoprotein-I antibodies are associated with adverse IVF outcomes.

The purpose of the study is to evaluate the effects of anticardiolipin (aCL) and/or anti-β2-glycoprotein-I (aβ2GPI) antibodies, namely antiphospholipid antibodies (aPL), on in vitro fertilization (IVF)outcomes. The study group comprised infertile women with aPL undergoing IVF-ET cycles. Controls were infertile women with tubal etiology without aPL. The impact of aPL on reproductive outcomes, such as oocyte quality, embryo quality, and implantation capacity, was compared between the study group and controls. Additionally, peripheral blood T cell subsets, such as T helper (Th)1, Th2, Th17, and T regulatory (Treg) cells and cytokines, were analyzed by the flow cytometry. Differences between the study group and controls were analyzed. A total of 132 infertile women, including 44 women with aPL, and 88 controls were sequentially recruited for this study. Women with aPL had lower numbers of total and perfect/available embryos and lower rates of MII oocytes, blastocyst formation, perfect and available embryos, implantation, clinical pregnancy, and take-home baby. Additionally, imbalanced Th1/Th2 and Th17/Treg ratios, significantly higher levels of serum IL-2, TNF-α, IFN-γ, and IL-17A, and a significantly lower serum IL-4 were noticed in women with aPL compared to controls. Women with aPL such as aCL and/or aβ2GPI antibodies were associated with adverse IVF outcomes. Early screening for aPL and appropriate consultation for couples undergoing IVF should be considered. In addition, underlying immunopathology and inflammatory immune mechanisms associated with aPL should be further explored.

Platelet- and endothelial-derived microparticles in the context of different antiphospholipid antibody profiles.

Studies on microparticles (MPs) in patients with antiphospholipid antibodies (aPL) are sparse and inconclusive. The relation between MPs and different aPL antibody profiles has never been tested. We evaluated the presence of platelet and endothelial microparticles in patients positive for IgG anti-β2-glycoprotein I (aβ2GPI) antibodies according to triple, double and single positive aPL profiles. Megamix (Biocytex) was used to set up the MPs gating according to the datasheet. Markers of Platelet Microparticles (PMPs) were CD41a-PE and annexin-V-FITC that was used to determine phosphatidylserine (PS) exposure. CD144-FITC was used as a marker of Endothelial Microparticles (EMPs). The number of total MPs and EMPs was significantly higher in triple positive groups with respect to single positive group and showed a significant correlation with IgG aβ2GPI titers. The number PMPs was the lowest in triple positive group and inversely correlated with IgG aβ2GPI titers. Elevated levels of total MPs and EMPs suggest a state of vascular activation in IgG aβ2GPI positive individuals according to the number of positive tests. PMPs may be fast cleared from circulation in high risk triple positive patients.

Antiphospholipid antibodies in the obstetric antiphospholipid syndrome: Detection and antibodies profile at the Maternity and Neonatal Medicine Center of Monastir, Tunisia.

This study aimed to implement lupus anticoagulant (LAC) detection techniques according to the International Society on Thrombosis and Hemostasis (ISTH) recommendations, in the Biological Laboratory of the Maternity and Neonatal Medicine Center (Monastir, Tunisia) and to evaluate the profile and the prevalence of antiphospholipid antibodies (aPL) in the obstetric antiphospholipid syndrome (OAPS). We collected two groups: a "case group" (53 women who presented one or more obstetrical criteria of APS) and a "control group." LAC was detected following the four steps recommended by ISTH 2009. Anticardiolipin (aCL) and antibeta-2-glycoprotein I (aβ2GPI) antibodies testing were performed by enzyme-linked immunosorbent assay (ELISA). aPL were found in five patients: three patients with isolated LAC, one patient with isolated IgG aCL, and one patient with triple positivity (LAC, aCL IgM, aβ2GPI IgM). Concerning LAC, 13 (24.52%) of 53 patients had a screening step with at least one positive test. The mixing step was positive in four patients and then confirmed in the confirmatory test. Thus, the prevalence of LAC in our study group is 7.54%. Surprisingly, among these positive patients, one patient had an associated combined factor V (FV) and factor VIII (FVIII) deficiency. There is no single test and no algorithm that can detect all types of LAC. It seems that the recent 2020 ISTH algorithm allows a better detection of low activity LAC than the 2009 algorithm. In our study, the most frequently identified antiphospholipid antibodies were LAC more than aCL and aβ2GPI.

Secondary antiphospholipid syndrome at a young male

Antiphospholipid syndrome (APS) is an autoimmune disease characterized by recurring venous and/or arterial thrombosis and the presence of circulating antiphospholipid antibodies. APS occurs as a primary condition or secondary to other autoimmune disorders, mainly systemic lupus erythematosus (SLE). The diagnosis of APS is made on the basis of suggestive clinical findings and the presence of one or more of the following antiphospholipid antibodies (LAC, aCL antibody or aβ2GPI antibody present on two or more occasions, at least 12 weeks a part). A clinically significant aPL profile has been detected in approximately 30 % of patients with SLE. Case presentation: We are presenting a rare case of a 23 years old male with complaints of dyspnea, retrosternal discomfort, fatigue, general weakness, joint pain over a period of 3 months. The patient reported a single syncopal episode, 3 months prior to admission as his first clinical manifestation. He was at first diagnosed with Thrombocytopenia in 2007 and Systemic Lupus Erythematosus (SLE) in 2020. During his hospitalization, the patient experienced recurrent headaches, dizziness and episodes of elevated blood pressure (170/100 mmHg), as well. Moreover, laboratory and imaging examinations showed bilateral pulmonary thromboembolism and positive Anticardiolipin antibodies, positive ANA, positive SSA &amp; SSB. Conclusion: Given the lack of typical clinical findings in the early stages of the disease, establishing a diagnosis of APS can be challenging. Although APS is one of the most common thrombocytophilias, unfortunately, it remains underdiagnosed. Clinicians should investigate for the presence of antiphospholipid antibodies, as early diagnosis may influence the course of the disease.

Detection of IgA Antiphospholipid Antibodies Does not Improve Thrombotic Antiphospholipid Syndrome Classification: A two-Center Study.

BackgroundThrombotic antiphospholipid syndrome (APS) is a systemic autoimmune disease; its diagnosis requires meeting both clinical and laboratory criteria. Prevalence rates of immunoglobulin (Ig) A anticardiolipin antibodies (aCL) and IgA anti-β2 glycoprotein I antibodies (aβ2GPI) remain unknown, and the clinical value of these antibodies to APS classification remains controversial. Therefore, we aimed to examine both items in the Chinese population.MethodsUsing chemiluminescence immunoassay, antiphospholipid antibodies (aPL) were quantified in 12,582 hospital-based general population, 278 thrombotic APS patients, and 233 healthy controls.ResultsIn the general population, the positive rates of IgA aCL and IgA aβ2GPI antibodies were 2.87% and 1.99%, respectively. Furthermore, isolated IgA aPL-positivity rate was 0.72% in patients with APS, which was comparable to those in the general population (0.68%, p = 1) and in healthy controls (0.43%, p = 1). Among the IgA aPL-positive individuals in the general population, isolated IgA-positive individuals had lower serum levels of IgA antibodies (p = 0.007 for IgA aCL and p = 0.059 for IgA aβ2GPI). Regarding to APS classification, adding IgA aPL into conventional aPL assays may not improve and may even deteriorate the net reclassification index for APS; besides, no association between thrombosis and IgA aPL was observed.Conclusionsthis study assessed the prevalence of various aPL in Chinese population. IgA aPL may not enhance the classification ability of established laboratory criteria for thrombotic APS. Our data do not support the addition of IgA aPL to conventional aPL assays.

O22 Pregnancy planning in non-criteria antiphospholipid syndrome

Case report - IntroductionAntiphospholipid Syndrome (APS) is an autoimmune condition manifested by vascular thrombosis with or without pregnancy related morbidities. APS classification criteria require detection of persistent antibodies: Anti-Cardiolipin Antibody (aCL), Anti-Beta Glycoprotein I (ab2GPI) and circulating Lupus Anticoagulant (LAC).Criteria for the diagnosis of obstetric antiphospholipid syndrome allow for optimal treatment planning in pregnancy and reduction of foetal and maternal morbidity. There are, however, several “non-criteria” features of APS, including late pre-eclampsia, which may also infer adverse obstetric outcomes.We highlight a treatment dilemma in a young female with lupus and APS with history of previous pregnancy that was complicated by pre-eclampsia.Case report - Case descriptionWe describe a case of a 26-year-old female with systemic lupus erythematosus (SLE), “triple positive” APS markers (aPL) and non-criteria APS obstetric morbidity.During her first pregnancy she presented at 22 weeks with severe and frequent migraine episodes. She had no other active clinical manifestations of SLE. There was no prior history of pregnancy and therefore no previous obstetric morbidity nor had she had any vascular thrombotic episodes. She had been commenced on low-dose aspirin (LDA) at the start of her pregnancy and was already taking hydroxychloroquine (HCQ). The dose of HCQ was increased to 400mg daily leading to improvement in the headaches. She had persistent strong ACL antibodies, positive LAC and ab2GPI antibodies. ANA was positive with hypocomplementemia and neutropenia but normal range double-stranded DNA antibodies.After discussion with a tertiary centre, it was recommended to continue HCQ and LDA. Low molecular weight heparin (LMWH) was not proposed as she did not fulfil criteria for obstetric APS. Her pregnancy was subsequently complicated by pre-eclampsia and post-partum sepsis.Two years later she sought advice to plan her second pregnancy, raising important questions as to whether the same treatment strategy should be followed or if alternative approaches should be considered, given the history of pre-eclampsia and its association with APS. Again, she did not meet the international consensus (revised Sapporo) criteria for diagnosis of obstetric APS.After further discussion with the tertiary centre, she commenced high-dose aspirin 150mg/day alone. Uterine artery dopplers were recommended and LMWH proposed if bilateral notching was noted. Dopplers were normal.Her blood pressure (BP) fluctuates between 130-145mmHg systolic. She has occasional crops of mouth ulcers but no other SLE features. Migraines continue every 2—3 weeks although severe attacks are infrequent. C4 is persistently low with normal Ds DNA and urine protein/creatinine ratio.Case report - DiscussionOur case raises questions on how pregnancy should be safely managed in patients without a prior history of APS-related pregnancy complications but who nevertheless have risk factors, in the form of APS antibody positivity and non-criteria obstetric manifestations of APS. Her previous pregnancy was treated with LDA and HCQ which had proved insufficient in avoiding the outcome of pre-eclampsia.The objective of prophylactic treatments is to prevent adverse outcomes such as miscarriage, which carry significant maternal morbidity including psychological manifestations such as depression and anxiety. In first pregnancies, mothers have no existing obstetric history, such that current treatment guidance provides few recommendations for preventative interventions, even where other risk factors are apparent. Furthermore, non-criteria manifestations of obstetric APS are now well recognised, which may further highlight potential risk for obstetric morbidity but fail to trigger interventions as they are not included within the current international criteria. These manifestations include late pre-eclampsia, placental abruption and late pregnancy loss, unexplained in vitro fertilisation failures, two unexplained miscarriages and three non-consecutive miscarriages. Low positive antibody titres and intermittent aPL are also included.Studies suggest that women with non-criteria APS may benefit from standard treatment for obstetric APS which includes LMWH in addition to aspirin, with good pregnancy outcomes.HCQ has a dose-dependent effect in preventing thrombosis through inhibition of platelet aggregation and aPL Ab-related thrombosis. However, pregnancy itself is a prothrombotic condition and in the presence of persistent triple positive aPL is a risk factor for adverse pregnancy outcomes.Further studies are needed to define the risk of non-criteria APS on pregnancy outcomes and define optimal treatment strategies.Case report - Key learning pointsObstetric APS carries significant risk for maternal foetal morbidity including miscarriage and pre-term birth.Significant maternal psychological effects are recognised even following a single miscarriage.The international consensus (revised Sapporo) criteria for diagnosis of obstetric antiphospholipid syndrome exclude certain non-criteria clinical and laboratory manifestations that may confer adverse pregnancy outcomes.First pregnancies are challenging to risk stratify in patients with identified aPL as there will be no prior pregnancy history to reference.Ultrasound doppler velocimetry is a useful non-invasive tool to diagnose poor placental perfusion, a predictor of obstetric complications, hence identifying high-risk pregnancies.Further research is required to establish the diagnostic validity, predictive value, and treatment implications of non-criteria manifestations of obstetric APS.

Anti-phosphatidyl-serine/prothrombin antibodies (aPS/PT) in isolated lupus anticoagulant (LA): is their presence linked to dual test positivity?

Anti phosphatidylserine/prothrombin antibodies (aPS/PT) are often present in patients with antiphospholipid syndrome (APS) and might be relevant in the pathogenesis of this condition. They are major determinant of lupus anticoagulant (LA) in triple-positive antiphospholipid (aPL) profile. Whether they are present and pathogenic in patients with isolated LA [negative anticardiolipin (aCL) and anti β2-glycoprotein I (aβ2GPI) antibodies] is a matter of debate. We measured aPS/PT in a large number of isolated LA with the aim to ascertain whether there is a link between the way isolated LA is assessed and the presence of these antibodies. APS/PT were measured in 86 patients with isolated LA (aCL- and abeta2GPI-). LA was assessed by two test systems, the dilute Russell Viper Venom Time (dRVVT) and the Silica Clotting Time (SCT). Sixty-six (77%) individuals with isolated LA were positive for aPS/PT (IgM 44, IgG and IgM 15, IgG in 7). Diagnosis of LA was made based on positive results in both dRVVT and SCT in 40 patients (Group 1) and based on only one positive test in the remaining 46 patients (Group 2). The rate of positive aPS/PT antibodies was significantly higher in Group 1 (OR=7.2, 95% CI 1.9-27.0, p<0.002). Moreover, the titre of IgM aPS/PT was significantly increased in Group 1 as compared to Group 2 (137 U, IQR 64-179 vs. 43 U, IQR 11-120, p=0.008). These data indicate an association between LA based on two positive coagulation tests and the presence of aPS/PT antibodies, especially of IgM isotype.

The Identification of High Risk APS Patients for Thrombosis with Triple Antiphospholipid Antibody Positivity Is Platform Dependent

The antiphospholipid syndrome (APS) is characterized by thrombosis and/or specific pregnancy morbidity with the persistent presence of antiphospholipid antibodies (aPL). Laboratory criteria include aPL detection by a functional assay referred to as lupus anticoagulant (LAC) or by quantitative solid phase assays measuring anti-β2glycoprotein I (aβ2GPI) and anti-cardiolipin (aCL) IgG/IgM antibodies. Triple positivity (i.e. positivity for LAC, aCL and aβ2GPI antibodies irrespective of the isotype) is associated with a high risk for both a first thrombotic event and recurrence. For these high-risk triple positive patients, a repetitive aPL measurement proved not to be required. Reports from external quality control programs illustrate that commercially available aPL assays produce variable results, probably originating from differences in assay design, epitope exposure and a lack of standardization. On the contrary, the detection of triple positivity was recently suggested to be method and platform independent. In a large multicentre study, we aimed to investigate the variability in triple positivity detection and its clinical association between different aPL platforms.In this study we included 853 patients from seven European medical centers. Patients were classified by the local centers resulting in 259 thrombotic APS patients, 204 diseased controls for thrombosis, 196 patients with autoimmune diseases other than APS and 194 patients without any clinical and laboratory criteria for APS. Four platforms, ACL AcuStar (Instrumentation Laboratory, Bedford, MA, USA), Bioplex 2200 (Bio-Rad Laboratories, Hercules, CA, USA), ImmunoCap EliA (ThermoFisher (Phadia), Waltham, MA, USA) and QUANTA Lite ELISA (Inova Diagnostics, San Diego, CA, USA), were selected based on frequency of use and the willingness of manufacturers to provide their assays. All samples with all assays were tested at one location by a single technician. Lupus anticoagulant positivity was determined by the local center, according to the ISTH guidelines.From the 259 patients diagnosed with thrombotic APS, 202 were positive for LAC. Detection of triple positivity proved to be variable between platforms: 118, 101, 111 and 89 detected with Bioplex, ImmunoCap EliA, AcuStar and QUANTA Lite respectively. To investigate the diagnostic efficacy of triple positivity of the different platforms, we calculated the sensitivity, specificity and odds ratio (OR) for thrombosis. The sensitivity of triple positivity for thrombosis was low and varied from 19% up to 26% between the tested platforms (Figure 1A). However, a high specificity for thrombosis with minor variation from the platforms was obtained ranging from 93% up to 96% (Figure 1A). Looking at the OR for thrombosis, triple positivity was significantly correlated with thrombosis independent of the platform used (Figure 1B). However, the OR for thrombosis ranged from 4.2 up to 5.2 for the different platforms used to detect aβ2GPI and aCL aPL.Taken together, our study confirmed the high-risk profile for thrombosis associated with triple positivity, independent of the platform used to detect aβ2GPI and aCL aPL. Contrary, the number of triple positives is dependent on the platform used, resulting in varying sensitivities of triple positivity for thrombosis over the different platforms. The high risk on recurrent clinical complications in triple positive APS patients often requires them to take indefinite oral anticoagulant treatment. Therefore, to avoid misclassification of high-risk APS patients, standardization/uniformity of solid phase assays for the diagnosis of APS is urgently warranted. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

VWF, Platelets and the Antiphospholipid Syndrome.

The antiphospholipid syndrome (APS) is characterized by thrombosis and/or pregnancy morbidity with the persistent presence of antiphospholipid antibodies (aPLs). Laboratory criteria for the classification of APS include the detection of lupus anticoagulant (LAC), anti-cardiolipin (aCL) antibodies and anti-β2glycoprotein I (aβ2GPI) antibodies. Clinical criteria for the classification of thrombotic APS include venous and arterial thrombosis, along with microvascular thrombosis. Several aPLs, including LAC, aβ2GPI and anti-phosphatidylserine/prothrombin antibodies (aPS/PT) have been associated with arterial thrombosis. The Von Willebrand Factor (VWF) plays an important role in arterial thrombosis by mediating platelet adhesion and aggregation. Studies have shown that aPLs antibodies present in APS patients are able to increase the risk of arterial thrombosis by upregulating the plasma levels of active VWF and by promoting platelet activation. Inflammatory reactions induced by APS may also provide a suitable condition for arterial thrombosis, mostly ischemic stroke and myocardial infarction. The presence of other cardiovascular risk factors can enhance the effect of aPLs and increase the risk for thrombosis even more. These factors should therefore be taken into account when investigating APS-related arterial thrombosis. Nevertheless, the exact mechanism by which aPLs can cause thrombosis remains to be elucidated.

Insight into the hypercoagulable state of high‐risk thrombotic APS patients: Contribution of aβ2GPI and aPS/PT antibodies

ObjectiveMost high‐risk thrombotic antiphospholipid syndrome (APS) patients test positive for anti‐β2‐glycoprotein I (aβ2GPI) and anti‐phosphatidylserine/prothrombin (aPS/PT) antibodies. Information on the influence of these antibodies on thrombin generation and activated protein C resistance (aPCr) is still sparse and contradictory. MethodsPlasma of 16 patients poured into a β2GPI affinity column allowed the perfect separation of aβ2GPI and aPS/PT antibodies. aPS/PT antibodies were further purified through a prothrombin affinity column. Obtained material was spiked into normal pooled plasma (NPP) and tested in the thrombin generation assay in the absence or presence of aPC. ResultsaPS/PT antibodies showed a marked anticoagulant effect. Affinity purified aPS/PT and aβ2GPI antibodies from five patients were compared. aPS/PT antibodies showed significantly prolonged lag time and time to peak (5.0 minutes [interquartile range (IQR)3.5–6.1] versus 2.7 minutes [IQR2.2–3.5], P = .03 and 8.7 minutes [IQR6.7–10.3] versus 5.7 minutes [IQR4.5–6.2], P = .05, respectively) and significantly lower peak and velocity index (143 nmol/L [IQR131–163] versus 171 nmol/L [IQR157–182], P = .03 and 35 nmol/L/min [IQR32–59] versus 72 nmol/L/min [IQR54–77], P = .03, respectively). When aPC was added to the system, aPCr was significantly increased compared to controls for both aβ2GPI and aPS/PT antibodies. However, it was significantly stronger using aPS/PT antibodies. Median inhibition of endogenous thrombin potential was 22% (IQR16–33) with aPS/PT compared to 52% (IQR46–56) with aβ2GPI antibodies (P = .002). ConclusionsAβ2GPI antibodies show a mild anticoagulant and moderate procoagulant effect in thrombin generation and moderate aPC resistance. Conversely, aPS/PT antibodies show a strong anticoagulant effect and a strong aPCr.

Incidence of a First Thrombo-Embolic Event in Patients With Systemic Lupus Erythematosus and Anti-phosphatidylserine/prothrombin Antibodies: A Prospective Study.

Objective: This study aimed to prospectively investigate the incidence of first thromboembolic events (TEs) in a cohort of systemic lupus erythematosus (SLE) patients. The patients were positive for anti-phosphatidylserine/prothrombin (aPS/PT) antibodies and tested negative for anticardiolipin (aCL) and anti-β2–glycoprotein I (aβ2GPI) antibodies [regardless of their Lupus Anticoagulant (LA) status].Methods: Inclusion criteria included: (a) SLE with no previous TEs; (b) no concomitant anti-thrombotic therapy; (c) isolated confirmed positive test for aPS/PT.Results: From the total of 52 SLE patients (42, 80.8% women), 18 patients (34.6%) were found to be positive for aPS/PT (IgG/IgM). During a mean follow-up (3.9 ± 1.1 years), 3 TEs occurred (1.3%/year). The overall cumulative incidence of TEs was 5.8% after 2 years, and up to 16.7% when focusing on aPS/PT positive patients. All the TEs events (two cerebrovascular events and one thrombotic kidney microangiopathy) occurred in the aPS/PT positive group. When focusing on IgG aPS/PT, we found that patients who tested positive were at a significantly higher risk for TEs (crude HR 19.6, 95%; CI 1.1 to 357.6; p < 0.05) compared to patients with negative aPS/PT.Conclusion: This study observed a rate of TEs of 1.3%/year, in aPS/PT positive only patients. Our prospective data suggest that aPS/PT might confer an increased risk for the development of TEs in SLE patients.

Immunoglobulin A Isotype of Antiphospholipid Antibodies Does Not Provide Added Value for the Diagnosis of Antiphospholipid Syndrome in a Chinese Population.

ObjectiveAntiphospholipid syndrome (APS) is characterized by the presence of anti-phospholipid (aPL) antibodies. However, the relationship between the immunoglobulin (Ig) A isotype of aPL positivity and its clinical utility in APS diagnosis is controversial. Presently, we determine the clinical utility of IgA–aPL from consecutive patients in a large cohort from the Chinese population and patients with APS whose aPL profiles were obtained.MethodsThe detection of anticardiolipin (aCL) and anti-β2 glycoprotein-Ⅰ (aβ2GPⅠ) antibodies of the IgA/IgG/IgM isotype by paramagnetic particle chemiluminescent immunoassay was carried out in sera from 7293 subjects. 153 primary APS (PAPS) patients and 59 patients with secondary APS (SAPS) were included in this study.ResultsIn total, 1,082 out of 7,293 (2.55%) subjects had a positive IgA–aPL test, and the prevalence of isolated IgA–aPL was 0.29% (21/7,293) in the general population. The prevalence of IgA–aPL in the PAPS patients was 12.42% (19/153); however, only one patient (0.65%) presented with isolated IgA–aPL. Fifty (25.9%) of the SAPS had IgA–aPL, none of whom lacked IgG/IgM–aPL. The combination of the IgA isotype and the IgG/IgM isotype did not increase the diagnostic performance when compared with the IgG/IgM isotype of aCL or aβ2GPⅠ, respectively. IgA–aPL was not associated with clinical manifestation in patients with APS.ConclusionIsolated IgA–aPL is rare in the general population as well as in patients with APS. Whether in the laboratory or in clinical practice, the presence of IgA–aPL does not provide added value for the diagnosis of APS in the Chinese population.

\u201cNon-criteria\u201d antiphospholipid antibodies add value to antiphospholipid syndrome diagnoses in a large Chinese cohort

BackgroundDespite expansion in the 2006 Sydney antiphospholipid syndrome (APS) classification criteria to include IgG/IgM anti-β2-glycoprotein (aβ2GPI) antibodies in addition to IgG/IgM anti-cardiolipin antibodies (aCL) and lupus anticoagulant (LAC), some individuals with clinical features of APS remain seronegative (seronegative APS or SNAPS) and are at risk of recurrent thrombosis and pregnancy morbidities. Our aim was to assess the value of “non-criteria” aPL antibodies to detect these SNAPS patients.MethodsOne hundred ninety-two APS patients, 90 SNAPS patients, 193 autoimmune disease controls, and 120 healthy controls were evaluated. Ten antiphospholipid antibodies (aPLs) were tested using commercial kits, including 5 non-criteria aPLs: anti-phosphatidylserine/prothrombin antibodies (aPS/PT) IgG/IgM, aCL IgA, aβ2GPI IgA, and anti-β2GPI Domain 1 (aβ2GPI-D1) IgG.ResultsUp to 60.9% of the SNAPS and 93.5% of APS patients were detected by at least one non-criteria aPL. aPS/PT IgG had the highest Youden index in classifying APS and SNAPS from controls. aPS/PT IgG and aβ2GPI Domain 1 IgG seem to be the most significant risk factors for thrombotic events and pregnancy morbidity, respectively. aPS/PT IgG/IgM and aβ2GPI-D1 IgG were detected in some SNAPS patients, while IgA isotypes of aCL/aβ2GPI tended to appear together with other biomarkers. The combined analysis showed enhanced diagnostic performance with the inclusion of non-criteria aPLs.ConclusionsRecognition of SNAPS patients is critical for clinical management and prevention of potential thrombotic and obstetric adverse events. The non-criteria antiphospholipid antibodies help to identify a considerable portion (60.9%) of these patients who otherwise may remain untreated and at clinical risk.