Taipan snake venom time has high sensitivity for lupus anticoagulants in non-anticoagulated, triple positive antiphospholipid syndrome patients.

INTRODUCTION: Dilute Russell's viper venom time (dRVVT) and activated partial thromboplastin time (APTT) are the mainstay assays in lupus anticoagulant (LA) detection yet they have limitations, particularly in relation to interferences and specificity. The recently validated Taipan snake venom time (TSVT) screening with ecarin time (ET) confirmatory assays overcome many of those limitations due to the innate specificity engendered from direct prothrombin activation, and insensitivity to the effects of vitamin K antagonists (VKA). The present study aimed to further evidence diagnostic utility of TSVT/ET by performing them in samples from 116 nonanticoagulated patients with established triple-positive antiphospholipid syndrome (APS). METHODS: Samples were identified in three expert centres who performed dRVVT, APTT and solid phase antiphospholipid antibody assays with reagents from a variety of manufacturers. All samples additionally received TSVT/ET analysis using standardised reagents. RESULTS: Ninety seven of 116 (83.6%) were dRVVT- and APTT-positive, 85/97 (87.6%) of which were TSVT/ET-positive, 9/116 (7.8%) were dRVVT-positive only, 6 of which were TSVT/ET-positive, and 10/116 (8.6%) were APTT-positive only, 5 of which were TSVT/ET-positive. 96/116 TSVT/ET-positivity returned a high sensitivity for LA of 82.8%. Low coefficients of determination revealed weak relationships between LA potency and anticardiolipin and anti-ß2-glycoprotein I antibody titres for all three LA assays. CONCLUSIONS: TSVT/ET has high sensitivity for the clinically significant LA found in triple positive APS patients. TSVT/ET can establish multiple LA assay positivity in nonanticoagulated patients negative for one of dRVVT or APTT, and is the only assay pairing insensitive to VKAs, the recommended anticoagulation for APS.

'Non-criteria antiphospholipid antibodies': bridging the gap between seropositive and seronegative antiphospholipid syndrome.

OBJECTIVE: We aimed to analyse the prevalence of non-criteria anti-phospholipid (aPL) antibodies and their role in the diagnosis, treatment and prognosis in a cohort of patients with clinical features consistent with a diagnosis of antiphospholipid syndrome (APS), but persistently negative for criteria aPL - anti-cardiolipin antibodies (aCL), anti-ß2-glycoprotein I antibodies (aß2-GPI) and lupus anticoagulant (LA) - named seronegative APS (SN-APS). METHODS: Sera from SN-APS patients were tested for aCL by TLC-immunostaining, anti-vimentin/cardiolipin (aVim/CL) and anti-phosphatidylserine/prothrombin (anti-PS/PT) by ELISA. Control groups of our study were APS patients and healthy controls. RESULTS: We enrolled 114 consecutive SN-APS patients, 69 (60.5%) resulted positive for at least one non-criteria test in two occasions 12 weeks apart. Among the persistently positive patients to these tests, 97% resulted positive for aCL by TLC-immunostaining, 52.3% for aVim/CL and 17.4% for aPS/PT. SN-APS patients with double positivity (aCL by TLC-immunostaining and aVim/CL) showed a likelihood positive ratio of 8 to present mixed thrombotic and obstetrical features. Among SN-APS patients tested positive, after the therapeutic changes, three cases of recurrent thrombosis were observed [median follow-up 41 months (IQR 39.5)]. Twenty pregnancies were recorded in 17 SN-APS patients after the detection of unconventional aPL and 12 of them (60%) experienced a good outcome under conventional treatment for APS. CONCLUSIONS: This is the largest monocentric study demonstrating that aCL tested by TLC-immunostaining and aVim/CL can detect aPL positivity in SN-APS. It may encourage clinicians to monitor and provide adequate targeted therapy, which improve SN-APS prognosis.

Anti-Phosphatidylserine/Prothrombin Antibodies at Two Points: Correlation With Lupus Anticoagulant and Thrombotic Risk.

Antibodies to phospholipids (aPL) and associated proteins are a hallmark in the diagnosis of anti-phospholipid syndrome (APS). Those included in the classification criteria are the lupus anticoagulant (LA) and the IgG and IgM isotypes of anticardiolipin (aCL) and anti-beta-2 glycoprotein I (ß2GPI) antibodies. Non-classification criteria markers such as autoantibodies that recognize the phosphatidylserine/prothrombin (aPS/PT) complex have been proposed as biomarkers for APS. Studies of aPS/PT antibodies have shown a strong correlation to clinical manifestations and LA. We aimed to study the value and the persistence of aPS/PT IgG and IgM antibodies in a cohort of consecutive patients with clinical suspicion of APS and their utility as thrombotic risk markers. Our study, with 103 patients, demonstrates that persistently positive results for aPS/PT IgG antibodies were significantly associated with APS classification, thrombosis, triple aPL positivity, LA positive result, and the Global APS Score (GAPSS) > than 9 points (p < 0.01, for each condition). On the other hand, no association was seen with pregnancy morbidity (p = 0.56) and SLE (p = 0.07). Persistence of aPS/PT antibodies, defined according to the current laboratory classification criteria, likely improves the diagnosis and clinical assessment of patients with APS.

Clinical and laboratory characteristics of Brazilian versus non-Brazilian primary antiphospholipid syndrome patients in AntiPhospholipid Syndrome Alliance for Clinical Trials and InternatiOnal Networking (APS ACTION) clinical database and repository.

BACKGROUND: Antiphospholipid syndrome (APS) is characterized by episodes of thrombosis, obstetric morbidity or both, associated with persistently positive antiphospholipid antibodies (aPL). Studying the profile of a rare disease in an admixed population is important as it can provide new insights for understanding an autoimmune disease. In this sense of miscegenation, Brazil is characterized by one of the most heterogeneous populations in the world, which is the result of five centuries of interethnic crosses of people from three continents. The objective of this study was to compare the clinical and laboratory characteristics of Brazilian vs. non-Brazilian primary antiphospholipid syndrome (PAPS) patients. METHODS: We classified PAPS patients into 2 groups: Brazilian PAPS patients (BPAPS) and PAPS patients from other countries (non-BPAPS). They were compared regarding demographic characteristics, criteria and non-criteria APS manifestations, antiphospholipid antibody (aPL) profile, and the adjusted Global Antiphospholipid Syndrome Score (aGAPSS). RESULTS: We included 415 PAPS patients (88 [21%] BPAPS and 327 [79%] non-BPAPS). Brazilian patients were significantly younger, more frequently female, sedentary, obese, non-white, and had a higher frequency of livedo (25% vs. 10%, p < 0.001), cognitive dysfunction (21% vs. 8%, p = 0.001) and seizures (16% vs. 7%, p = 0.007), and a lower frequency of thrombocytopenia (9% vs. 18%, p = 0.037). Additionally, they were more frequently positive for lupus anticoagulant (87.5% vs. 74.6%, p = 0.01), and less frequently positive to anticardiolipin (46.6% vs. 73.7%, p < 0.001) and anti-ß2-glycoprotein-I (13.6% vs. 62.7%, p < 0.001) antibodies. Triple aPL positivity was also less frequent (8% vs. 41.6%, p < 0.001) in Brazilian patients. Median aGAPSS was lower in the Brazilian group (8 vs. 10, p < 0.0001). In the multivariate analysis, BPAPS patients still presented more frequently with livedo, cognitive dysfunction and sedentary lifestyle, and less frequently with thrombocytopenia and triple positivity to aPL. They were also less often white. CONCLUSIONS: Our study suggests a specific profile of PAPS in Brazil with higher frequency of selected non-criteria manifestations and lupus anticoagulant positivity. Lupus anticoagulant (not triple positivity) was the major aPL predictor of a classification criteria event.

A Novel ELISA Assay for the Detection of Anti-Prothrombin Antibodies in Antiphospholipid Syndrome Patients at High Risk of Thrombosis.

Autoantibodies targeting prothrombin (aPT) can be found in antiphospholipid syndrome (APS) patients. However, their detection has proven difficult to standardize. Here, we developed a new ELISA assay to improve the identification of aPT and compared its performance with currently available anti-phosphatidylserine/prothrombin antibodies (aPS/PT) and autoantibodies targeting prothrombin bound to the plastic plate (aPT-A) assays using a cohort of 27 APS patients at high risk of thrombosis. We generated a novel prothrombin variant, ProTS525A-Biot, carrying an artificial tag at the C-terminus suitable for site-specific biotinylation and added the mutation S525A to improve stability. ProTS525A-Biot was immobilized to neutravidin-coated plates at the desired density and with a defined orientation, i.e., pointing the N-terminal fragment-1 toward the solvent. Antibodies against ProTS525A-Biot (aPT-Bio) were found in 24 out of 27 triple-positive APS patients (88%). When compared to aPS/PT and aPT-A, aPT-Bio showed an excellent linear correlation with aPS/PT (R2 = 0.85) but not with aPT-A (R2 = 0.40). Since aPS/PT but not aPT-A are an emerging biomarker of thrombosis in APS, this method may find utility for detecting pathogenic aPT in APS but also other prothrombotic conditions such as COVID-19.

The Diagnostic Value of New Additional Antiphospholipid Antibodies in Antiphospholipid Syndrome.

BACKGROUND: The antiphospholipid syndrome (APS) is an autoimmune disease that is characterized by thrombosis and/or pregnancy failure and associated with the presence of all or at least one of three standard antibodies (anti-phospholipid (aPL) antibodies, including lupus anticoagulant (LA), anti-cardiolipin (aCL), and anti-ß2-glycoprotein I (anti-ß2GPI)). A growing body of evidence recommends adding additional aPL antibodies, such as anti-phosphatidylserine (aPS), anti-prothrombin (aPT), and anti-annexin A5 (aAA5), to conventional laboratory tests (revised Sapporo criteria), especially in seronegative APS cases. OBJECTIVES: We aimed to compare the diagnostic value, utility, and performance of these three additional antibodies along with the standard aPL antibodies in cases with confirmed and non-criteria APS (seronegative). METHODS: This was a prospective observational study on 59 patients who presented with clinical features of APS at the hematology, medical, rheumatology, and obstetric clinics. LA was detected by standard coagulation tests, while other aPL, IgG, and IgM antibodies (aCL, aß2GPI, aPS, aPT, aAA5) were detected with enzyme-linked immunosorbent assay (ELISA). RESULTS: Anti-PS antibody was more frequent compared to aPT and aAA5 in both confirmed cases (84.6%) and non-criteria (seronegative) (15.4%) APS. As a single test, the aPS antibody was significantly better (P<0.05) than the aPT and aAA5 antibodies in the detection of APS cases. Seven non-criteria patients were confirmed using additional aPL antibodies. Among these patients, four, two, and one patient was confirmed with aPS, aPT, and aAA5 antibodies, respectively. CONCLUSION: Our data support the findings of previously published studies and attribute the clinical significance of additional aPL antibodies, particularly aPS, in identifying non-criteria APS cases. In the future, along with conventional aPL antibodies, these additional antibodies should be included as standard laboratory tests in the revised Sapporo criteria.

Cerebrovascular events in patients with isolated anti-phosphatidyl-serine/prothrombin antibodies.

The interest of extra-criteria antiphospholipid antibodies is growing, especially in patients negative for conventional antibodies. In this study we aimed to assess the clinical utility of anti-phosphatidyl-serine/prothrombin antibodies (aPS/PT) testing in patients negative for Beta2-Glycoprotein 1(ß2GPI)-dependent tests, for identifying antiphospholipid syndrome (APS) patients that developed cerebrovascular events (CVE). When screening APS patients attending our center, out of 119 aPS/PT IgG/IgM-positive patients, thus patients negative for aß2GPI and aCL, 42 patients (35%) tested negative for ß2GPI-dependent tests and were tested with thrombin generation assay (TGA). Ten patients (24%), with isolated aPS/PT IgG/IgM, had a history of CVE. Lupus anticoagulant (LA)-positive test was more frequently observed in patients with CVE (8/22 vs. 2/20; p = 0.045). Out of the 10 patients who experienced CVE, 3 patients were aPS/PT IgG positive (all LA positive), and 8 patients were aPS/PT IgM positive (6/8 LA positive). One patient was positive for both aPS/PT IgG and IgM. LA-positive patients had only high titers of aPS/PT IgG/IgM, all of them being ≥ 80 U/ml, while the 2 LA-negative patients were aPS/PT IgM positive with medium titers [40-60 U/ml]. LA-positive patients had significantly altered TGA profile when compared to those who were LA negative, considering all TGA parameters. LA-positive patients had significantly higher tLag (8.4 ± 3.3 min vs. 6.6 ± 1.8 min; p = 0.046), higher tPeak (14 ± 4.3 min vs. 11 ± 2.7 min; p = 0.015) and lower Peak (207 ± 152 nM vs. 356.3 ± 104.7 nM; p < 0.001) and lower AUC (2109.7 ± 1006.9 nM vs. 2772.5 ± 776.8 nM; p = 0.033). The use of aPS/PT might be of help in identifying patients with CVE and APS, as also confirmed by TGA testing.

Association between plasmatic oxidative stress and thrombosis in primary antiphospholipid syndrome.

Antiphospholipid antibodies induce a pro-inflammatory and hypercoagulable state that lead to increased risk of thrombosis. Whether oxidative damage contributes thrombosis risk is a matter of debate. We evaluated the association between oxidative stress and thrombosis in primary antiphospholipid syndrome (t-PAPS). Plasma total antioxidant capacity and the levels of malondialdehyde (TBARs), carbonyl protein, and 8-isoprostane in plasma were determined in a group of patients with t-PAPS and in individuals without a history of thrombosis (controls) using commercial ELISA assays. The levels of these plasma markers of oxidative stress were compared between t-PAPS and controls using Mann-Whitney test. A total of 70 patients with t-PAPS and 74 controls were included. Overall, measurements of all plasma oxidative stress markers were similar between t-PAPS patients and controls. In a subgroup analysis, patients with t-PAPS and arterial thrombosis had a higher antioxidant capacity as compared to controls. Thrombotic PAPS was not associated with increased levels of oxidative stress markers, in comparison with individuals without thrombosis. Even though it is not possible to rule out that a mild oxidative damage, not detected by plasma markers, occurs in t-PAPS, our results suggest that measuring plasma oxidative stress markers has limited clinical relevance in t-PAPS.

Antiphospholipid antibodies and cerebrovascular thrombosis in the pediatric population: Few answers to many questions.

Most of the knowledge in pediatric antiphospholipid syndrome (APS) is derived from studies performed on the adult population. As in adults, antiphospholipid antibodies (aPL) can contribute to thrombosis, especially cerebrovascular thrombosis, in neonates and children. Since aPL have the potential to cross the placental barrier, and since the pediatric population is prone to infections, re-testing for their positivity is essential to specify their role in cerebrovascular thrombosis.In this review, we aimed at assessing the prevalence of aPL, criteria or non-criteria, in neonatal and childhood ischemic stroke and sinovenous thrombosis trying to find an association between aPL and cerebrovascular thrombosis in the neonatal and pediatric population. Also, we looked into the effect of aPL and anticoagulants/antiplatelets on the long term neurological outcomes of affected neonates or children. The questions regarding the prevalence of aPL among pediatric patients with cerebrovascular thrombosis, the relationship between the titers of aPL and incidence and recurrence of cerebrovascular events, the predictability of the long term neurological outcomes, and the most optimal anticoagulation plan are still to be answered. However, it is crucial for clinicians to screen neonates and children with cerebrovascular thrombosis for aPL and confirm their presence if positive.

Meta-analysis on aspirin combined with low-molecular-weight heparin for improving the live birth rate in patients with antiphospholipid syndrome and its correlation with d-dimer levels.

BACKGROUND: Antiphospholipid antibody syndrome (APS) is a systemic, autoimmune, prothrombotic disease characterized by persistent antiphospholipid antibodies, thrombosis, recurrent abortion, complications during pregnancy, and occasionally thrombocytopenia. At present, there is no consensus on the treatment of this disease. Long-term anticoagulation is recommended in most cases in patients with thrombotic APS. This study aimed to evaluate whether aspirin combined with low-molecular-weight heparin (LMWH) can improve the live birth rate in antiphospholipid syndrome and its correlation with D-dimer. METHODS: The data were retrieved from the WanFang Data, CBM, VIP, CNKI, the Cochrane Library, PubMed, EMBASE, OVID, and Web of Science databases. We collected data on randomized controlled trials of aspirin combined with LMWH in the treatment of pregnant women with APS. The "Risk of Bias Assessment" tool and the "Jadad Scale" provided by the Cochrane Collaboration were used to evaluate the risk of bias and quality of the collected literature. The risk ratio (RR) and its 95% confidence interval (CI) were determined using Statase-64 software. RESULTS: In this study, a total of 11 studies were included, comprising a total of 2101 patients. The live birth rate in pregnant women with APS was higher on administration of aspirin combined with LMWH than with aspirin alone (RR = 1.29, 95% CI = 1.22-1.35, P < .001). d-dimer concentration in plasma predicted the live birth rate, which was higher below the baseline than above it (RR = 1.16, 95% CI = 1.09-1.23, P < .001). The subgroup analysis of the live birth rate was carried out based on the course of treatment, and the results were consistent with the overall results. Begg funnel plot test revealed no publication bias. Sensitivity analysis showed that deleting any study did not affect the results. CONCLUSION: Aspirin combined with LMWH for APS may improve live birth rate, and detection of d-dimer levels in APS pregnant women may predict pregnancy complications and guide the use of anticoagulants.

Anti-vimentin/cardiolipin IgA in the anti-phospholipid syndrome: A new tool for 'seronegative' diagnosis.

Anti-phospholipid syndrome (APS) is a systemic autoimmune disorder defined by the simultaneous presence of vascular clinical events, pregnancy morbidity and anti-phospholipid antibodies (aPL). In clinical practice, it is possible to find patients with APS who are persistently negative for the routine aPL tests (seronegative APS; SN-APS). Recently, the identification of aPL immunoglobulin (Ig)A and/or anti-ß2-glycoprotein-I (ß2-GPI) IgA was shown to represent a further test in SN-APS patients. In this study we analyzed the presence of anti-vimentin/cardiolipin (aVim/CL) IgA in a large cohort of patients with SN-APS, evaluating their possible association with clinical manifestations of the syndrome. This study includes 60 consecutive SN-APS patients, 30 patients with APS and 40 healthy donors. aVim/CL IgA were detected by enzyme-linked immunosorbent assay (ELISA). Results show that 12 of 30 APS patients (40%) and 16 of 60 SN-APS patients (26.7%) resulted positive for aVim/CL IgA. Interestingly, SN-APS patients who tested positive for aVim/CL IgA showed a higher prevalence of arterial thrombosis (p = 0.017, likelihood positive ratio = 5.7). This study demonstrates for the first time, to our knowledge, the presence of aVim/CL IgA in sera of patients with APS. In particular, they revealed a potential usefulness in identification of a significant proportion of SN-APS patients. Moreover, as patients tested positive for aVim/CL IgA reported a high likelihood ratio to have the clinical features of APS, this test may be considered a suitable approach in the clinical evaluation of SN-APS.

Clinical relevance of nitrated beta 2-glycoprotein I in antiphospholipid syndrome: Implications for thrombosis risk.

Β2-Glycoprotein I (ß2GPI) is an important anti-thrombotic protein and is the major auto-antigen in the antiphospholipid syndrome (APS). The clinical relevance of nitrosative stress in post translational modification of ß2GPI was examined.The effects of nitrated (n)ß2GPI on its anti-thrombotic properties and its plasma levels in primary and secondary APS were determined with appropriate clinical control groups. ß2-glycoprotein I was nitrated at tyrosines 218, 275 and 309. ß2-glycoprotein I binds to lipid peroxidation modified products through Domains IV and V. Nitrated ß2GPI loses this binding (p < 0.05) and had diminished activity in inhibiting platelet adhesion to vWF under high shear flow (p < 0.01). Levels of nß2GPI were increased in patients with primary APS compared to patients with either secondary APS (p < 0.05), autoimmune disease without APS (p < 0.05) or non-autoimmune patients with arterial thrombosis (p < 0.01) and healthy individuals (p < 0.05).In conclusion tyrosine nitration of plasma ß2GPI is demonstrated and has important implications with regards to the pathophysiology of platelet mediated thrombosis in APS. Elevated plasma levels of nß2GPI in primary APS may be a risk factor for thrombosis warranting further investigation.

Failure of Anticoagulation to Prevent Stroke in Context of Lupus-Associated Anti-Phospholipid Syndrome and Mild COVID-19.

Hypercoagulability and virally-mediated vascular inflammation have become well-recognized features of the SARS-CoV-2 virus infection, COVID-19. Of growing concern is the apparent ineffectiveness of therapeutic anticoagulation in preventing thromboembolic events among some at-risk patient subtypes with COVID-19. We present a 43-year-old female with a history of seropositive-antiphospholipid syndrome and systemic lupus erythematosus who developed an acute ischemic stroke in the setting of mild COVID-19 infection despite adherence to chronic systemic anticoagulation. The clinical significance of SARS-CoV-2-mediated endothelial cell dysfunction and its potential to cause macrovascular events in spite of full anticoagulation warrants further investigation and likely represents another disease-defining pathology of COVID-19.

Ferritin, fever, and frequent visits: Hyperferritinemic syndromes in the emergency department.

Fever of unknown origin (FUO) is defined as persistent fevers without an identifiable cause despite extensive medical workup. Emergency physicians caring for patients reporting a persistent, nonspecific, febrile illness should carefully consider potentially serious non-infectious causes of FUO. We present a case of a 35-year-old man who presented to the emergency department (ED) three times over a 10-day period for persistent febrile illness and was ultimately diagnosed with Adult-Onset Still's Disease (AOSD) after a serum ferritin level was found to be over 42,000 µg/L. AOSD, along with macrophage activation syndrome, catastrophic antiphospholipid syndrome, and septic shock comprise the four hyperferritinemic syndromes. These are potentially life-threatening febrile illnesses that characteristically present with elevated ferritin levels. In this article, we highlight the value of a serum ferritin level in the workup of a patient with prolonged febrile illness and its utility in facilitating early diagnosis and prompt treatment of hyperferritinemic syndromes in the ED.

miR-19b-3p and miR-20a-5p are associated with the levels of antiphospholipid antibodies in patients with antiphospholipid syndrome.

Monocytes play a key role in pathophysiology of antiphospholipid syndrome (APS), nevertheless it is unclear if microRNA expression is associated with particular APS features. Identify whether miR-19b-3p and miR-20a-5p expression in monocytes are associated with hallmarks of the APS. Fifty-seven APS patients and 18 healthy controls were studied. Expression of miR-19b-3p and miR-20a-5p was measured in monocytes by RT-qPCR. Both miR-19b-3p (AUC = 0.835, 95% CI 0.733-0.938; P < 0.001) and miR-20a-5p (AUC = 0.857, 0.757-0.957; P < 0.001) discriminated APS patients from healthy individuals. A cut-off point of 1.98 for miR-19-3p and 2.18 for miR-20a-5p showed that APS patients with low microRNA expression had higher levels of IgM and IgG anticardiolipin antibodies than patients with high microRNA expression. In addition, APS patients with low microRNA expression had higher IgG anti-ß2 glycoprotein I antibody levels than their counterparts with high microRNA expression. Finally, miR-19b-3p and miR-20a-5p expression levels were significantly higher in APS patients using oral anticoagulants. Monocyte expression of miR-19b-3p and miR-20a-5p is low in APS, and patients with the lowest microRNA expression presented the highest levels of antiphospholipid antibodies.

Case Report: Resetting the Humoral Immune Response by Targeting Plasma Cells With Daratumumab in Anti-Phospholipid Syndrome.

Introduction: Monoclonal antibodies (mAb) targeting plasma cells are malignant gammopathy designed and approved therapies. In recent years, these antibodies have also been increasingly introduced for non-malignant conditions such as autoimmune-mediated diseases. The Anti-Phospholipid Syndrome (APS) is an immune-mediated disorder in which autoantibodies against phospholipid associated proteins could elicit the activation of the coagulation cascade in specific situations. Therefore, the mainstream treatment for APS patients is the use of anticoagulant therapy. However, there are refractory patients who would benefit from targeting the antibodies rather than their effects. Rituximab, a B-cell depleting mAb, and intravenous immunoglobulins (IVIG) have been used in APS patients without showing a clear beneficial effect or a significant drop in anti-phospholipid antibody (aPL) levels. Clinical case: We present our first APS case treated with daratumumab, an anti-CD38 mAb, in a 21-year-old patient with APS who presented with recurrent venous thromboembolic events despite adequate anticoagulant therapy. She tested positive for lupus anticoagulant, anti-cardiolipin IgG, anti-beta-2-glycoprotein-I IgG and anti-phosphatidylserine/prothrombin IgG and IgM. She was administered one dose weekly of daratumumab for 4 weeks. The treatment showed an adequate safety profile and was well tolerated. The patient was discharged after undergoing a clinically significant improvement. After the therapy, her levels of positive aPL declined significantly and most continued to decrease during the next three months. The patient experienced a new thrombotic episode two years after the therapy associated with poor adherence to antithrombotic therapy. Conclusions: The treatment with daratumumab showed an adequate safety profile, was well tolerated and led to a significant clinical improvement. Levels of aPL lowered on therapy and the next three months and then rose again during follow-up. Further investigation is needed to better elucidate the role and optimal timing and doses of daratumumab in treatment of refractory APS.

Anticardiolipin and other antiphospholipid antibodies in critically ill COVID-19 positive and negative patients.

BACKGROUND: Reports of severe COVID-19 being associated with thrombosis, antiphospholipid antibodies (APLA), and antiphospholipid syndrome have yielded disparate conclusions. Studies comparing patients with COVID-19 with contemporaneous controls of similar severity are lacking. METHODS: 22 COVID-19+ and 20 COVID-19- patients with respiratory failure admitted to intensive care were studied longitudinally. Demographic and clinical data were obtained from the day of admission. APLA testing included anticardiolipin (aCL), anti-ß2glycoprotien 1 (ß2GP1), antidomain 1 ß2GP1 and antiphosphatidyl serine/prothrombin complex. Antinuclear antibodies (ANAs) were detected by immunofluorescence and antibodies to cytokines by a commercially available multiplexed array. Analysis of variance was used for continuous variables and Fisher's exact test was used for categorical variables with α=0.05 and the false discovery rate at q=0.05. RESULTS: APLAs were predominantly IgG aCL (48%), followed by IgM (21%) in all patients, with a tendency towards higher frequency among the COVID-19+. aCL was not associated with surrogate markers of thrombosis but IgG aCL was strongly associated with worse disease severity and higher ANA titres regardless of COVID-19 status. An association between aCL and anticytokine autoantibodies tended to be higher among the COVID-19+. CONCLUSIONS: Positive APLA serology was associated with more severe disease regardless of COVID-19 status. TRIAL REGISTRATION NUMBER: NCT04747782.