Diagnostic Biomarkers of Amyloid and Tau Pathology in Alzheimer's Disease: An Overview of Tests for Clinical Practice in the United States and Europe.

Amyloid and tau biomarkers for Alzheimer's disease are widely recognized diagnostic tools for the identification of Alzheimer's disease pathology antemortem and are recommended by the most recent clinical and research guidelines. Approved biomarkers include positron emission tomography (PET)- and fluid-based markers derived from cerebrospinal fluid and, more recently, plasma. These biomarkers are still infrequently used in clinical practice, potentially due to challenges in access to and understanding of individual assay information and methodology. We provide an overview of the diagnostic biomarkers for amyloid and tau pathology that are currently available in the US and/or EU for clinical use. Available performance data from both labels/instructions for use and the scientific literature (with focus on autopsy or PET as standard of truth) are summarized to help healthcare providers navigate the biomarker landscape. All available PET amyloid and tau biomarkers demonstrate high accuracy in identifying amyloid and tau Alzheimer's disease pathology, respectively, at autopsy. Among cerebrospinal fluid biomarkers, all showed accurate prediction of Alzheimer's disease pathology, either based on autopsy or PET findings; greater accuracy was evident for concentration ratios (Aß42/40 or P-tau181/Aß42) versus individual biomarker concentrations. Among plasma biomarkers, Aß42/40 and P-tau181 demonstrated high agreement with PET findings. Overall, we conclude that commercially available PET, cerebrospinal fluid and plasma assays accurately identify Alzheimer's disease amyloid and tau pathology. The recent development of fully automated tests for fluid-based biomarkers improves test reliability. The continued development of plasma biomarkers holds promise for the future management of patients with Alzheimer's disease.

The interferon in idiopathic inflammatory myopathies: Different signatures and new therapeutic perspectives. A literature review.

Idiopathic inflammatory myopathies (IIM), even though sharing common clinical manifestations, are characterized by diversified molecular pathogenetic mechanisms which may account for the partial inefficacy of currently used immunomodulatory drugs. In the last decades, the role of interferon (IFN) in IIM has been extensively elucidated thanks to genomic and proteomic studies which have assessed the molecular signature at the level of affected tissues or in peripheral blood across distinct IIM subtypes. A predominant type I IFN response has been shown in dermatomyositis (DM), being especially enhanced in anti-melanoma differentiation-associated gene 5 (MDA5)+ DM, while a type 2 IFN profile characterizes anti-synthetase syndrome (ASyS) and inclusion body myositis (IBM); conversely, a less robust IFN footprint has been defined for immune-mediated necrotizing myopathy (IMNM). Intracellular IFN signaling is mediated by the janus kinase/signal transducer and activator of transcription (JAK/STAT) through dedicated transmembrane receptors and specific cytoplasmic molecular combinations. These results may have therapeutic implications and led to evaluating the efficacy of new targeted drugs such as the recently introduced janus kinase inhibitors (JAKi), currently approved for the treatment of rheumatoid arthritis, psoriatic arthritis, and ankylosing spondylitis. In this review we aim to summarize the most significant evidence of IFN role in IIM pathogenesis and to describe the current state of the art about the ongoing clinical trials on IFN-targeting drugs, with particular focus on JAKi.

SARS-CoV-2 infection in patients with autoimmune rheumatic diseases in northeast Italy: A cross-sectional study on 916 patients.

BACKGROUND: Whether patients with autoimmune rheumatic diseases (ARD) have a higher risk for SARS-CoV-2 infection (COVID-19) and how SARS-CoV-2 pandemic impacts on adherence to therapy has not been fully elucidated. We assessed the rate and clinical presentation of COVID-19, and adherence to therapy in a large cohort of patients with ARD followed-up in a tertiary University-Hospital in Northeast Italy. METHODS: Between April 9th and April 25th, 2020, after SARS-CoV-2 infection peak, a telephone survey investigating the impact of COVID-19 on patients with systemic lupus erythematosus (SLE), systemic sclerosis (SSc), rheumatoid arthritis (RA), ANCA-associated vasculitis (AAV), and idiopathic inflammatory myopathies (IIM) was administered. Demographics, disease activity status, therapy, occupational exposure, and adherence to social distancing advise were also collected. RESULTS: 916 patients (397 SLE, 182 AAV, 176 SSc, 111 RA, 50 IIM) completed the survey. 148 patients developed at least one symptom compatible with COVID-19 (cough 96, sore throat 64, fever 64, arthromyalgias 59, diarrhea 26, conjunctivitis 18, ageusia/hyposmia, 18). Among the 916 patients, 65 (7.1%) underwent SARS-CoV-2 nasopharyngeal swab (18 symptomatic and 47 asymptomatic), 2 (0.21%) tested positive, a proportion similar to that observed in the general population of the Veneto region. No deaths occurred. 31 patients (3.4%) withdrew ≥1 medication, mainly immunosuppressants or biologics. Adoption of social distancing was observed by 860 patients (93.9%), including 335 (36.6%) who adopted it before official lockdown. CONCLUSIONS: COVID-19 incidence seems to be similar in our cohort compared to the general population. Adherence to therapy and to social distancing advise was high.

Early Lupus Project: one-year follow-up of an Italian cohort of patients with systemic lupus erythematosus of recent onset.

Objective To describe the clinical and serological features of a prospectively followed cohort of early diagnosed systemic lupus erythematosus (SLE) patients during a one-year follow-up period. Methods SLE patients with disease duration less than 12 months were consecutively enrolled in a multicentre, prospective study. At study entry and then every 6 months, a large panel of data was recorded. Results Of 260 patients enrolled, 185 had at least 12 months of follow-up; of these, 84.3% were female, 92.4% were Caucasians. Mean diagnostic delay was about 20 months; higher values of European Consensus Lupus Activity Measurement (ECLAM) and of organs/systems involved were both associated with shorter diagnostic delay. Clinical and serological parameters improved after study entry. However, patients' quality of life deteriorated and cardiovascular risk factors significantly increased. About one-third of patients with active disease at study entry went into remission (ECLAM = 0). Negative predictors for remission were: oral ulcers, arthritis, low C4, anti-SSB (Ro) antibodies and therapy with mycophenolate. There was a widespread use of glucocorticoids both at baseline and during follow-up. Conclusion Clinical symptoms and serological parameters improve during the first period after diagnosis. However, patients' quality of life deteriorates. The widespread use of glucocorticoids is probably the reason for the early significant increase of some cardiovascular risk factors.

Targeting Neuroinflammation to Treat Alzheimer's Disease.

Over the past few decades, research on Alzheimer's disease (AD) has focused on pathomechanisms linked to two of the major pathological hallmarks of extracellular deposition of beta-amyloid peptides and intra-neuronal formation of neurofibrils. Recently, a third disease component, the neuroinflammatory reaction mediated by cerebral innate immune cells, has entered the spotlight, prompted by findings from genetic, pre-clinical, and clinical studies. Various proteins that arise during neurodegeneration, including beta-amyloid, tau, heat shock proteins, and chromogranin, among others, act as danger-associated molecular patterns, that-upon engagement of pattern recognition receptors-induce inflammatory signaling pathways and ultimately lead to the production and release of immune mediators. These may have beneficial effects but ultimately compromise neuronal function and cause cell death. The current review, assembled by participants of the Chiclana Summer School on Neuroinflammation 2016, provides an overview of our current understanding of AD-related immune processes. We describe the principal cellular and molecular players in inflammation as they pertain to AD, examine modifying factors, and discuss potential future therapeutic targets.

Value and goals of treat-to-target in systemic lupus erythematosus: knowledge and foresight.

Treat-to-target is a therapeutic strategy aimed at improving disease outcome through the achievement of shared treatment goals, which has dramatically ameliorated the prognosis of widespread disorders, such as hypertension or diabetes. Conversely, efforts to delineate treat-to-target in systemic lupus erythematosus (SLE) have failed in pinpointing common goals and treatment strategies, probably because of disease heterogeneity and lack of measurable biomarkers predicting disease course and ensuring a safe treatment tapering during quiescence. Given the detrimental effects of persistent disease activity and protracted corticosteroid therapy on patients' outcome in lupus, disease remission should be pursued whenever possible. Fortunately, clinical remission is currently realistic for a greater number of patients than it was in the past, yet tight monitoring is required in order for patients to benefit from disease- and corticosteroid-free intervals, while minimizing the risk of disease flares. In everyday practice, patients should be brought to the lowest level of disease activity ensuring a significant benefit over a persistently active disease, being either clinical remission or low disease activity.

The olfactory function is impaired in patients with idiopathic inflammatory myopathies.

The aim of our study was to analyze olfactory function in patients with idiopathic inflammatory myopathies (IIM). We performed a case-control study on 60 IIM patients (48 females and 12 males) and 60 healthy controls (HC) recruited by the best friend method, matched for age, sex and lifestyle. Olfactory function was analyzed by "Sniffin' sticks test" and expressed through a score (TDI), indicating normosmia (TDI > 30), hyposmia (TDI 15-30) and anosmia (TDI < 15). Mood was investigated by Beck depression inventory (BDI) test. Statistic was performed using SPSS package. Mean ± SD TDI was significantly reduced in patients versus HC (26.8 ± 5.2 vs. 31.4 ± 3.5, p < 0.001). Anosmia was detected in two patients (3.3 %) and no HC, hyposmia in 41 patients and 14 HC (68.3 vs. 23.3 %, p < 0.0001) and normosmia in 17 patients and 48 HC (28.3 vs. 76.6 %, p < 0.0001). In the multivariate analysis carried out in the pool population of patients and HC, low TDI score was associated with age ≥50 years (p < 0.0001), disease status (p < 0.0001) and high BDI (p = 0.007). When adjusting for BDI, disease status was still associated with low TDI (p = 0.037). In IIM, TDI was lower in subjects aged ≥50 years (p = 0.008) and in patients who were taking corticosteroids (p < 0.0001). In the multivariate analysis carried out in IIM patients, low TDI was associated with age ≥50 years (p = 0.001) and prednisone intake (p < 0.0001). The olfactory function is impaired in IIM patients. An underlying immune-mediated mechanism is conceivable, yet a possible interference due to age, steroid intake and depression should be considered.

Assessment of patients with idiopathic inflammatory myopathies and isolated creatin-kinase elevation.

Idiopathic inflammatory myopathies (IIM) are a group of diseases characterized by inflammation of the skeletal muscle. Weakness, mainly affecting the proximal muscles, is the cardinal muscular symptom in IIM. In patients with dermatomyositis, peculiar skin lesions are observed. The assessment of patients with IIM includes clinical and laboratory evaluation, and clinimetric measurements. Different tools have been proposed to measure muscular and extramuscular disease activity and damage in patients with IIM. A core set of measurements to use in clinical practice was recently proposed. Among laboratory features the increase of serum creatine kinase (CK) is considered a hallmark of muscle inflammation/damage. However, subjects with persistent CK elevation, without any evidence of a definite myopathy, are often seen in clinical practice and need a careful assessment. Indeed, CK blood levels can also increase in non-myopathic conditions, e.g. in case of intense physical exercise, assumption of some drugs (statins), muscular dystrophy, muscular trauma or in case of neuro-muscular disorders which all should be considered in the diagnostic work-up. The assessment of patients with IIM and hyperCKemia will be discussed in this paper.

Premature coronary heart disease in SLE: can we prevent progression?

Patients with systemic lupus erythematosus (SLE) have a higher prevalence of clinical and subclinical atherosclerosis compared with age- and sex-matched controls. Atherosclerosis progression is also accelerated in SLE, and coronary heart disease (CHD) is a major cause of morbidity and mortality. Traditional cardiovascular (CV) risk factors, including hypertension, diabetes mellitus or dyslipidemia, are more prevalent in SLE patients than in the general population, but they cannot fully account for accelerated atherosclerosis in SLE. In fact, a number of nontraditional risk factors have been identified, including disease activity, damage and various treatments. Preventive strategies for CHD are mandatory in SLE patients and should include giving up smoking; performing regular physical activity; managing metabolic abnormalities such as dyslipidemia, insulin resistance, and diabetes; treating persistent disease activity; and minimizing chronic exposure to corticosteroids. Low-dose aspirin, angiotensin-converting enzyme (ACE) inhibitors, vitamin D supplementation, antimalarials and, when indicated, some immunosuppressants such as mycophenolate mofetil should also be considered.

Clinical guidelines and definitions of autoinflammatory diseases: contrasts and comparisons with autoimmunity-a comprehensive review.

Autoinflammatory diseases (AIDs) and autoimmune diseases (ADs) are characterized by an aberrant chronic activation of the immune system which causes tissue inflammation and damage in genetically predisposed individuals. Pathogenetic mechanisms underlying this damage differ between these two types of diseases; in AIDs, the innate immune system is directly responsible for tissue inflammation, while in ADs it works by activating the adaptive immune system, which becomes the main effector of the inflammatory process. Despite the fact that AIDs have only been recently defined, they are older than ADs. The innate immune system is found in plants and animals, and it developed earlier than the adaptive immune system, which first appeared in jawed vertebrates. According to genetic background and clinical, serological, and radiological findings, AIDs and ADs might be considered as a single spectrum of disorders, with a wide range of manifestations. Indeed, autoinflammatory-like diseases have been reported in simple organisms such as Drosophila melanogaster and Caenorhabditis elegans. We analyzed here the main pathogenetic and clinical features of these two groups of diseases mostly dealing with their similarities and differences.

Polarization of TH2 response is decreased during pregnancy in systemic lupus erythematosus.

This study evaluated some cytokines involved in the Th1-Th2 shift during pregnancy in patients with systemic lupus erythematosus (SLE) and healthy women. Twenty-seven consecutive successful pregnancies in 26 SLE patients and 28 pregnancies in 28 matched healthy subjects, as controls, were enrolled and prospectively studied. Sera obtained at first and third trimesters of pregnancy were tested for IL-1α, IL-1ß, IL-2, IL-6, IL-8, IL-10, IL-12p70, INF-γ, and TNF-α with a highly sensitive, multiplexed sandwich ELISA (SearchLight Human Inflammatory Cytokine Array). Statistics were performed by SPSS package. IL-8 serum levels were higher in the first (P<0.0001) and third (P=0.003) trimesters of pregnancy in SLE patients compared with controls, INF-γ serum levels in the third trimester (P=0.009), and IL-10 serum levels in the first and third trimesters (P=0.055 and P<0.0001, respectively). IL-2 (r=0.524 P=0.010), IL-12 (r=0.549 P=0.007), IFN-γ (r=0.492 P=0.017), and IL-6 (r=0.515 P=0.020) serum levels correlated with disease activity in SLE patients in the first trimester of pregnancy. Cytokine profile was similar in patients with and without lupus nephritis both in the first and in the third trimesters of pregnancy. IL-8 serum levels were lower in patients with a previous diagnosis of antiphospholipid antibody syndrome compared with those without, both in the first and in the third trimesters of pregnancy. In SLE patients, a lower than expected decrease in Th1 cytokine serum levels was observed in the third trimester of gestation which could contribute to a lower Th2 cytokine polarization during pregnancy.

Autoinflammation and autoimmunity: bridging the divide.

As soon as autoinflammatory diseases (AIDs) emerged as new entities, they have been linked to the well known world of autoimmunity. In fact, AIDs and systemic autoimmune diseases (ADs), share some characteristics: they start with the prefix "auto" to define a pathological process directed against self; they are systemic diseases, frequently involving musculoskeletal system; both include monogenic and polygenic diseases. From the pathogenetic point of view, they are characterized by a chronic activation of immune system, which eventually leads to tissue inflammation in genetically predisposed individuals. Nevertheless, the specific effectors of the damage are different in the two groups of diseases: in AIDs the innate immune system directly causes tissue inflammation, whereas in ADs the innate immune system activates the adaptive immune system which, in turn, is responsible for the inflammatory process. Mutations in inflammasome-related proteins, particularly in NOD-like receptor (NLR) genes, have been strongly associated to the occurrence of AIDs, whereas the link between inflammasome and ADs is less clear. However, a role for this multiprotein-complex in some ADs can be postulated, since a wide spectrum of endogenous danger signals can activate NLRs and inflammasome products, including IL-1ß, can activate adaptive immunity. An association between single nucleotide polymorphisms (SNPs) localized in the inflammasome gene NLRP1 and systemic lupus erythematosus has recently been reported. AIDs and ADs are currently subdivided into two different groups, but looking at their similarities they might be considered as a single group of diseases with a large immune pathological and clinical spectrum which includes at one end pure ADs and at the other end pure AIDs.

Induction of the 'ASIA' syndrome in NZB/NZWF1 mice after injection of complete Freund's adjuvant (CFA).

Adjuvants, commonly used in vaccines, may be responsible for inducing autoimmunity and autoimmune diseases, both in humans and mice. The so-called 'ASIA' (Autoimmune/inflammatory Syndrome Induced by Adjuvants) syndrome has been recently described, which is caused by the exposure to a component reproducing the effect of adjuvants. The aim of our study was to evaluate the effect of injection of complete Freund's adjuvant (CFA) in NZB/NZWF1 mice, a lupus-prone murine model. We injected 10 NZB/NZWF1 mice with CFA/PBS and 10 with PBS, three times, 3 weeks apart, and followed-up until natural death. CFA-injected mice developed both anti-double-stranded DNA and proteinuria earlier and at higher levels than the control group. Proteinuria-free survival rate and survival rate were significantly lower in CFA-treated mice than in the control mice (p = 0.002 and p = 0.001, respectively). Histological analyses showed a more severe glomerulonephritis in CFA-injected mice compared with the control mice. In addition, lymphoid hyperplasia in spleen and lungs, myocarditis, and vasculitis were observed in the former, but not in the latter group. In conclusion, the injection of CFA in NZB/NZWF1 mice accelerated autoimmune manifestations resembling 'ASIA' syndrome in humans.

Atherosclerosis in psoriatic arthritis.

The atherosclerotic process is accelerated in several autoimmune rheumatic diseases. Effector cells of innate and adaptive immunity along with pro-inflammatory cytokines and other immune mediators are found in atherosclerotic lesions, where they play an important role in induction, progression and rupture of plaques. Psoriatic arthritis (PsA) is a chronic inflammatory disease, characterized by arthritis, enthesitis, dactilytis, osteitis, and axial involvement, along with skin manifestations. PsA is frequently associated with obesity, diabetes, dyslipidemia, hypertension, accelerated atherosclerosis and with increased cardiovascular morbidity and mortality. Disease-specific and traditional risk factors seem to account for the atherosclerotic burden in PsA patients. Some immunological factors which are involved in PsA can also contribute to atherosclerosis including C reactive protein (CRP), TNF-α, IFN-γ, IL-1, Il 6, IL23, and Th17.

Anti-annexins autoantibodies: their role as biomarkers of autoimmune diseases.

Annexins are a group of 12 highly conserved proteins which exert several regulatory functions on cell biology. There are involved in numerous cell processes including vesicle trafficking, calcium signaling, cell growth, division, and apoptosis. Autoantibodies directed toward annexin I, II, V and XI have been reported, but their role and their clinical correlates are controversial. Annexin I exerts an anti-inflammatory effect by suppressing the generation of inflammatory mediators and anti-annexin I antibodies were detected in patients affected with rheumatoid arthritis, systemic (SLE) and cutaneous lupus erythematosus. Annexin II and V have a high affinity for phospholipids playing a pivotal role in the regulation of coagulation cascade. Anti-annexin II and anti-annexin V antibodies were found in patients with arterial or venous thrombosis, especially in those with autoimmune rheumatic diseases (ARD) such as SLE, primary antiphospholipid syndrome (APS) or systemic sclerosis. Anti-annexin V antibodies were also found in patients with pregnancy loss with or without APS. Annexin XI is involved in several biological pathways, particularly apoptosis and cell proliferation. Anti-annexin XI antibodies have been found in patients with SLE, undifferentiated connective tissue disease, rheumatoid arthritis, Sjögren's syndrome and APS. The metanalysis of studies published up to now showed that the Odds Ratio for having an ARD in anti-annexin XI positive patients was 5.08 (95% CI 2.06-12.58).

OxLDL/beta2GPI-anti-oxLDL/beta2GPI complex and atherosclerosis in SLE patients.

It has been demonstrated that atherosclerosis (ATS) is enhanced in autoimmune rheumatic diseases, such as systemic lupus erythematosus (SLE). The reason for this accelerated process is still debatable and, although traditional risk factors are more prevalent in SLE patients than in general population, they do not seem to fully explain the enhanced risk. ATS has the characteristics of an autoimmune chronic disease, involving both the innate and the adaptive immunity. Moreover, it satisfies the four criteria defining an autoimmune disease, proposed by Witebsky and Rose. It has been shown that some autoantibodies, including anti-oxLDL, anti-beta(2)GPI, anti-HSP60/65, and more recently anti-oxLDL/beta(2)GPI, play a key role in the pathogenesis of ATS. However the role of these autoantibodies in accelerated ATS in SLE patients is still controversial. In fact, some of them seem to be proatherogenic and other protective; moreover, it has been demonstrated that induced oral tolerance has a protective role against ATS. We have recently observed that the levels of oxLDL/beta(2)GPI antigenic complexes and their antibodies were higher in patients with SLE than in healthy subjects, but we did not find a clear association between oxLDL/beta(2)GPI complexes and IgG or IgM anti-oxLDL/beta(2)GPI autoantibodies and subclinical ATS in SLE patients. Many other studies are required to explain the role of autoantibodies in the pathogenesis of ATS in SLE patients, because the characteristics of SLE seem to mask their effects for atherogenesis.

Anti-C1q antibodies in pregnant patients with systemic lupus erythematosus.

OBJECTIVE: To study anti-C1q antibodies in pregnant patients with systemic lupus erythematosus (SLE) and to evaluate their prognostic significance for the occurrence of disease flares or pregnancy complications. METHODS: Twenty-one pregnancies in 19 SLE patients prospectively followed were analyzed. Disease activity was evaluated on the basis of the physician's intention to treat and a modified version of the ECLAM index. Anti-C1q and anti-dsDNA antibodies were detected in the sera by an ELISA assay. Antinuclear antibodies, anti-ENA antibodies, anticardiolipin antibodies and lupus anticoagulant were also performed. RESULTS: In all the patients the disease was inactive at the beginning of the pregnancy. Four flares of disease activity were observed in 4 pregnancies (19%) and obstetric complications were encountered in 7 pregnancies (43%). Anti-C1q antibodies were positive in 4 (19%) pregnancies and anti-dsDNA antibodies in 8 (38%). The presence of anti-phospholipid antibodies at the first assessment was correlated with the occurrence of obstetric complications (p<0.05). The presence of anti-C1q and anti-dsDNA antibodies at the first assessment had no prognostic significance for the occurrence of flares or obstetric complications during the course of pregnancy. Although the small number of patients studied did not allow for statistically significant analysis, flares appeared to be more likely to occur in patients presenting with anti-dsDNA or anti-C1q antibodies during pregnancy compared to patients with no changes in these antibody titers (43% vs 8% respectively). CONCLUSIONS: The presence of anti-C1q and anti-dsDNA antibodies does not seem to be prognostic for the occurrence of flares during pregnancy. Further studies are warranted to explore this possibility.

Anti-prothrombin antibodies predict thrombosis in patients with systemic lupus erythematosus: a 15-year longitudinal study.

OBJECTIVE: To evaluate the role of anti-prothrombin (anti-PT) antibodies in predicting thrombosis in patients with systemic lupus erythematosus (SLE). METHODS: An inception cohort of 101 SLE patients (12 males, 89 females; mean age 30 +/- 8 years), was considered. Clinical and laboratory evaluations were regularly performed during a 15-year follow-up (median 108 months) with a special focus on thromboembolic events. Serum samples were collected at time of diagnosis and at least once a year thereafter. IgG and IgM anti-PT, anti-cardiolipin (aCL) and anti-beta(2)glycoprotein I (beta(2)GPI) antibodies were measured by enzyme-linked immunosorbent assay (ELISA); lupus anticoagulant (LAC) was assayed by the dilute Russell's viper venom time and activated partial thromboplastin time tests. The analytical specificity of anti-PT ELISA was investigated. The timing of thrombosis occurrence was calculated using the Kaplan-Meier method. RESULTS: In the 15-year follow-up, thrombosis occurred in 14 out of the 101 patients: venous thrombosis in nine cases and arterial thrombosis in five. IgG and/or IgM anti-PT, anti-beta(2)GPI and aCL antibodies, and LAC activity were detected in ten, nine, seven, and nine cases, with sensitivity for thrombosis of 71.4%, 64.3%, 50% and 64.3%, respectively. Thrombosis-free survival was 90% at 5 years and 85.8% at 10 and 15 years, respectively. Thrombosis was predicted by anti-PT (P = 0.001), anti-beta(2)GPI antibodies (P = 0.002) and LAC activity (P = 0.001). Moreover, the risk of thrombosis progressively increased with the number of positive antiphospholipid antibody tests. The presence of four positive antibody tests was associated with a risk of thrombosis thirtyfold higher than in their absence. CONCLUSIONS: This longitudinal study shows that IgG anti-PT antibodies are predictors of thrombosis in SLE patients.