16th International congress on antiphospholipid antibodies task force report on antiphospholipid syndrome laboratory diagnostics and trends.

Classification criteria for antiphospholipid syndrome (APS) require IgG or IgM isotypes of the anticardiolipin (aCL) antibodies, anti-ß2 glycoprotein I (anti-ß2GPI) antibodies, and/or the lupus anticoagulant (LA) to satisfy the laboratory disease definition. Over the past 20 years, non-criteria antiphospholipid antibodies (aPL) directed to other proteins of the coagulation cascade (i.e. prothrombin and/or phosphatidylserine-prothrombin complex) or to some domains of ß2GPI have been proposed. This task force concentrated and reviewed the literature on data including aPS/PT, antibodies to domain 4/5 of ß2GPI and the newly described antibodies to protein/HLA-DR complex. In addition, we discussed testing of LA in the 'new' oral anticoagulants' era and the value of triple positivity in the risk assessment of aPL. The conclusions were presented at a special session during the 16th International Congress on aPL, Manchester, UK, September 2019.

Autoantibodies: are they a clue for liver diseases?

Introduction: Autoantibody testing has contributed to both biological and clinical insights in managing patients with liver disease. These autoantibodies often have clinical value for the diagnosis, disease activity and/or prognosis. Aim of the study: We aimed to investigate the potential application of auto-antibodies in different etiologies of non-autoimmune liver diseases. Material and methods: This study was conducted on 53 infants and children with chronic liver diseases. The patients were subjected to clinical history and examination, laboratory investigations and abdominal ultrasound. Serum of all infants and children was tested for measurement of antiprothrombin antibody and anti-b2-glycoprotein I (ab2GPI) and anticardiolipin (ACL) auto-antibodies using a fully-automated enzyme linked immunosorbent assay (ELISA) system. Results: The mean age of the infants with cholestatic liver diseases was significantly lower than those with metabolic liver diseases, hepatitis C virus (HCV) and vascular liver diseases (p < 0.05). The gender distribution was proportionate in all groups (p = 0.703). Autoantibodies showed significant variations among different etiologies of chronic liver diseases. he incidence of ab2GPI and ACL was significantly increased in both HCV (94.7% and 78.9%, respectively) and vascular liver diseases patients (90.9% and 72.7%, respectively) (p < 0.05). Antiprothrombin antibodies were found in 81.8% of vascular liver disease patients. Interestingly, all types of autoantibodies were deficient in cholestatic and metabolic liver diseases. Conclusions: Testing for liver-related autoantibodies should be included in the workup of patients with chronic liver diseases. Further studies are needed to explain the cause-effect association of ACL, ab2GPI and antiprothrombin with chronic HCV and vascular liver diseases.

Antiprothrombin antibodies induce platelet activation: A possible explanation for anti-FXa therapy failure in patients with antiphospholipid syndrome?

BACKGROUND: Arterial and venous thrombosis are both common in antiphospholipid syndrome (APS). Recent studies have shown that anti-factor Xa (FXa) therapy in APS patients leads to a greater number of patients with arterial thrombosis than with warfarin. We hypothesize that this may be due to the lowering of prothrombin levels by warfarin. OBJECTIVES: To investigate whether antiprothrombin antibodies induce platelet aggregation and to identify the platelet receptors involved. A second aim was to investigate the effect of reduced prothrombin levels on antiprothrombin antibody-induced platelet aggregation. METHODS: Enzyme-linked immunosorbent assays were performed to measure binding of antiprothrombin antibodies to prothrombin fragment 1+2 and prothrombin. Platelet aggregation assays in washed platelets were performed. FcγRIIA was immunoprecipitated and tyrosine-phosphorylated FcγRIIA was measured by western blot. RESULTS: The antiprothrombin antibodies 28F4 and 3B1 had lupus anticoagulant (LAC) activity and caused platelet aggregation in the presence of Ca2+ and prothrombin. Antiprothrombin antibodies without LAC activity did not activate platelets. Inhibition of Syk and Src kinases and FcγRIIA blocked platelet aggregation. Fab and F(ab')2 fragments of 28F4 were unable to induce platelet aggregation. Immunoprecipitations showed that whole 28F4 immunoglobulin G induced tyrosine phosphorylation of FcγRIIA. Platelet aggregation was significantly reduced when prothrombin levels were reduced from 1 µM to 0.2 µM. CONCLUSIONS: Antiprothrombin antibodies with LAC activity are able to activate platelets via FcγRIIA. Decreased prothrombin levels resulted in less antiprothrombin antibody-mediated platelet aggregation. This may explain the lower incidence of arterial thrombosis in patients treated with warfarin than with anti-FXa therapy.

A woman with systemic lupus erythematosus, multiple pregnancy complications, and cerebral infarction who was only positive for phosphatidylserine-dependent antiprothrombin antibodies.

A woman with systemic lupus erythematosus (SLE) had a history of two abortions before the 10th week, two foetal deaths with normal morphology, and one premature before the 34th week with early-onset hypertensive disorder of pregnancy (HDP) and placental dysfunction. Although she did not have any conventional antiphospholipid antibodies (aPLs), antiphospholipid syndrome (APS) was strongly suspected based on her obstetric history and renal biopsy findings consistent with aPL-associated nephropathy (APLN). Eventually, she was found to be positive for phosphatidylserine-dependent antiprothrombin antibodies (aPS/PTs). A healthy baby was born with anticoagulation and intravenous immunoglobulin (IVIG) therapy during pregnancy. aPS/PT titres gradually increased after delivery. Cerebral infarction occurred at 9 years after birth. If APS is clinically suspected but the antibodies included in the classification criteria for APS are all negative, we should consider an association with unconventional aPLs and manage according to APS.

Added value of non-criteria antiphospholipid antibodies for antiphospholipid syndrome: lessons learned from year-long routine measurements.

The international classification criteria for definite antiphospholipid syndrome (APS) include three laboratory measurements: lupus anticoagulant (LA), IgG and IgM isotypes of anti-cardiolipin (aCL) and anti-ß2glycoprotein I antibodies (anti-ß2GPI). When persistently elevated, they are specific for APS; however, many patients that fulfil clinical criteria may exhibit negative serological results. These "seronegative" APS (SN-APS) are exposed to an increased thrombotic risk. The aims of our cross-sectional, retrospective study of consecutive autoimmune patients' samples were to evaluate the association of non-criteria antiphospholipid antibodies (aPL) with thrombosis and obstetric events, to calculate the risk score for adverse events and to assess the specific contribution of single aPL positivity in SN-APS. LA, aCL, anti-ß2GPI and anti-phosphatidylserine/prothrombin antibodies (aPS/PT) of IgG, IgM, and IgA isotypes were determined in sera of 323 patients with autoimmune disorders. Medical records of all patients were carefully analyzed. aCL, anti-ß2GPI and aPS/PT of IgG and IgA isotypes were significantly associated with thrombosis while none of the IgM aPL showed such association. aPS/PT of all isotypes, aCL and anti-ß2GPI of IgG and IgA isotype showed significant correlation to obstetric events. When considering results of aPS/PT ELISA, we could additionally identify 3% of thrombotic patients and 2% of obstetric patients. Thrombotic and obstetric risk scores were calculated showing significantly higher association to clinical events, as compared to evaluating individual risk factors. aPS/PT could represent an additional biomarker in SN-APS patients. IgA aPL are associated with thrombosis and obstetric complications. Risk scores accounting different aPL and conventional risk factors, better assesses risk for adverse event, as compared to evaluating individual factors alone.

Lupus anticoagulant-hypoprothrombinemia syndrome: report of two cases and review of the literature.

Lupus anticoagulant-hypoprothrombinemia syndrome (LA-HPS) is a rare acquired disorder caused by prothrombin antibodies. The disease is most common in the pediatric age group (<16 years), and more prevalent in women. There are well-established clinical diseases associated with LA-HPS, most notably systemic lupus erythematosus (SLE) and viral infections. The clinical manifestation of LA-HPS varies greatly in severity and it may cause severe life-threatening bleeding diathesis. LA-HPS is to be suspected when a patient presents with bleeding and a prolonged activated partial thromboplastin and prothrombin time, in combination with a lupus anticoagulant. The diagnosis is confirmed in the laboratory by identification of reduced prothrombin levels. There are no standardized recommendations for treatment of the hemorrhage associated with the syndrome; corticosteroids are used as first-line treatment. This review summarizes what is currently known about the pathogenesis, clinical features, diagnosis, treatment and prognosis of LA-HPS, and presents two case reports.

14th International Congress on Antiphospholipid Antibodies Task Force. Report on antiphospholipid syndrome laboratory diagnostics and trends.

Current classification criteria for definite Antiphospholipid Syndrome (APS) require the use of three laboratory assays to detect antiphospholipid antibodies (aCL, anti-ß2GPI and LA) in the presence of at least one of the two major clinical manifestations (i.e. thrombosis or pregnancy morbidity) of the syndrome. However, several other autoantibodies shown to be directed to other proteins or their complex with phospholipids have been proposed to be relevant to APS but their clinical utility and their diagnostic value remains elusive. This report summarizes the findings, conclusions and recommendations of the "APS Task Force 3-Laboratory Diagnostics and Trends" meeting that took place during the 14th International Congress on Antiphospholipid Antibodies (APLA 2013, September 18-21, Rio de Janeiro, RJ, Brazil).

Phosphatidylserine-dependent anti-prothrombin antibodies (aPS/PT) in infliximab-treated patients with inflammatory bowel diseases.

PURPOSE: To (1) examine the occurrence and concentrations of aPS/PT and aPL in inflammatory bowel disease (IBD) patients at the beginning of and during anti-TNF-alpha therapy with infliximab; (2) investigate the link of the aPS/PT and aPL presence with antibodies to infliximab (ATI) formation; and (3) examine possible clinical consequences of aPS/PT and/or aPL positivity in IBD patients. MATERIALS AND METHODS: Thirty (30) IBD patients treated with infliximab were analyzed regarding aPS/PT, aPL, and ATI antibody serum levels by standardized ELISAs at treatment weeks 2 (W2) and 14 (W14). RESULTS: At W2, 40 % of infliximab-treated patients had elevated aPS/PT and 16.7 % had elevated aPL serum levels. At W14, the proportion of aPS/PT-positive sera decreased to 16.6 %, whereas aPL distribution remained unchanged. Moreover, concentrations of aPS/PT have shown significant differences at W2 (16.64 [10.06; 33.06] U for IgG and 18.46 [9.18; 32.48] U for IgM) and at W14 (8.24 [2.78; 19.82] U for IgG and 8.57 [5.55; 26.82] U for IgM), p = 0.009 and p = 0.003, respectively. In ATI-positive samples, aPS/PT IgG were more frequent (p = 0.001 for W2 and p = 0.003 for W14), whereas aPS/PT IgM and aPL IgG/IgM did not show such association. CONCLUSIONS: Higher concentrations of aPS/PT IgG and IgM were found in IBD patients at the beginning of the biological treatment period compared to the maintenance treatment period. Moreover, aPS/PT IgG were more frequent in ATI-positive individuals, which was not observed in aPL. We speculate that there is a relationship between the aPS/PT and the severity of inflammation and auto-aggressive processes in IBD.

Reunión clínica inter-hospitales: síndrome antifosfolípidos catastrófico, un cuadro de microangiopatía / Catastrophic antiphospholipid syndrome, a case of microangiopathy

Se presenta el caso de una mujer joven, sin antecedentes de importancia, que muestra trombosis de grandes y pequeños vasos. A pesar del tratamiento con anticoagulación y corticoides en dosis altas, desarrolla necrosis cutánea y una importante respuesta inflamatoria sistémica con disfunción orgánica múltiple, por lo que .se le indicó plasmaféresis y, posteriormente, rituximab, con buena respuesta. Se discute el síndrome antifosfolípidos con énfasis en los anticuerpos antiprotrombina y la patogenia de la microangiopatía en el síndrome antifosfolípidos catastróficos.

We present the case of a young, otherwise healthy woman, who developed thrombosis of large and small vessels and capillaries. Despite anticoagulation treatment and high doses of glucocorticoids, she developed cutaneous necrosis and systemic inflammatory response with multiple organ dysfunction. Plasmapheresis and rituximab were administered with good response. We discuss the antiphospholipid syndrome, with emphasis on antiprothrombin antibodies and the pathogenesis of microangiopathy in antiphospholipid syndrome.