Ras guanine nucleotide-releasing protein 4 is aberrantly expressed in the fibroblast-like synoviocytes of patients with rheumatoid arthritis and controls their proliferation

OBJECTIVE

Ras guanine nucleotide-releasing protein 4 (RasGRP-4) is a calcium-regulated guanine nucleotide exchange factor and diacylglycerol/phorbol ester receptor not normally expressed in fibroblasts. While RasGRP-4-null mice are resistant to arthritis induced by anti-glucose-6-phosphate isomerase autoantibodies, the relevance of these findings to humans is unknown. We undertook this study to evaluate the importance of RasGRP-4 in the pathogenesis of human and rat arthritis.

METHODS

Synovial tissue from patients with rheumatoid arthritis (RA) and osteoarthritis (OA) were evaluated immunohistochemically for the presence of RasGRP-4 protein. Fibroblast-like synoviocytes (FLS) were isolated from synovial samples, and expression of RasGRP-4 was evaluated by real-time quantitative reverse transcription-polymerase chain reaction analyses. The proliferation potency of FLS was evaluated by exposing the cells to a RasGRP-4-specific small interfering RNA (siRNA). Finally, the ability of RasGRP-4-specific siRNAs to hinder type II collagen-induced arthritis in rats was evaluated to confirm the importance of the signaling protein in the disease.

RESULTS

Unexpectedly, RasGRP-4 protein was detected in the synovial hyperplastic lining, where proliferating FLS preferentially reside. FLS isolated from tissues obtained from a subpopulation of RA patients expressed much more RasGRP-4 than did FLS from examined OA patients. Moreover, the level of RasGRP-4 transcript was correlated with the FLS proliferation rate. The ability of cultured FLS to divide was diminished when they were treated with RasGRP-4-specific siRNAs. The intraarticular injection of RasGRP-4-specific siRNAs also dampened experimental arthritis in rats.

CONCLUSION

RasGRP-4 is aberrantly expressed in FLS and helps regulate their growth. This intracellular signaling protein is therefore a candidate target for dampening proliferative synovitis and joint destruction.

Primary prophylaxis to prevent obstetric complications in asymptomatic women with antiphospholipid antibodies: a systematic review

OBJECTIVE

Obstetric complications are common in patients with antiphospholipid syndrome. However, the impact of antiphosholipid antibodies (aPL) in the pregnancy outcomes of asymptomatic aPL carriers is uncertain. The aim of this systematic review is to assess whether primary prophylaxis is beneficial to prevent obstetric complications during pregnancy in asymptomatic women positive for aPL who have no history of recurrent pregnancy loss or intrauterine fetal death.

METHODS

Studies evaluating the effect of prophylactic treatment versus no treatment in asymptomatic pregnant aPL carriers were identified in an electronic database search. Design, population and outcome homogeneity of studies was assessed and meta-analysis was performed. The pooled Mantel-Haenszel relative risk of specific pregnancy outcomes was obtained using random effects models. Heterogeneity was measured with the I(2) statistic. All analyses were conducted using Review Manager 5.3.

RESULTS

Data from five studies involving 154 pregnancies were included and three studies were meta-analysed. The risk ratio and 95% confidence interval (CI) of live birth rates, preterm birth, low birth weight and overall pregnancy complications in treated and untreated pregnancies were 1.14 (0.18-7.31); 1.71 (0.32-8.98); 0.98 (0.07-13.54) and 2.15 (0.63-7.33),respectively. Results from the meta-analysis revealed that prophylactic treatment with aspirin is not superior to placebo to prevent pregnancy complications in asymptomatic aPL carriers.

CONCLUSION

This systematic review did not find evidence of the superiority of prophylactic treatment with aspirin compared to placebo or usual care to prevent unfavourable obstetric outcomes in otherwise healthy women with aPL during the first pregnancy.

The participations of the physicians on the diagnosis and treatments of antiphospholipid related pregnancy morbidities in Japan: from the result of nationwide survey

BACKGROUND

Thromboses and pregnancy morbidities are major pathologies of antiphospholipid syndrome (APS). In general, rheumatologists or hematologists see APS thrombosis patients, and they often give advices for the treatments of APS-related pregnancy morbidities, such as measurements and interpretations of antiphospholipid antibodies(aPL).

OBJECTIVE

To survey the approaches of physicians in Japan to the diagnosis and treatment of aPL-associated pregnancy morbidities.

METHOD

The study group on the Health and Labour Sciences Research Grants sent a questionnaire to 550 board members of the Japan College of Rheumatology and the Japanese Society on Thrombosis and Hemostasis, and analyzed the responses.

RESULT

The number of valid responses was 157 (28.5%). The number of pregnant women who were diagnosed as having APS was 118.7 patients/year in 53 of 157 hospitals (33.8%). With respect to aPL measurements, 128 out of 157 hospitals (81.5%) determined one or more anticardiolipin antibodies or β2GPI-dependent anticardiolipin antibodies with one or more lupus anticoagulants; however aPL tests of only 2 hospitals (1.3%) covered all aPLs defined in the classification criteria. The obstetricians were responsible for treatments in 33.1% to 42.3% of the hospitals. The treatment methods or duration of treatments did not reach to the general consensus.

CONCLUSION

The number of cases of aPL-related pregnancy complications that physicians have intervened was relatively small. There are considerable patients that are not diagnosed as having the disease due to insufficient aPL examinations. There were less involvement of physicians to the diagnosis and treatment of pregnant women with aPLs.

The efficacy of calcineurin inhibitors for the treatment of interstitial lung disease associated with polymyositis/dermatomyositis

Interstitial lung disease (ILD) in patients with polymyositis (PM) and dermatomyositis (DM) is often resistant to treatment and life threatening, being recognized as one of the severest complication in these autoimmune disorders. Patients with clinically amyopathic dermatomyositis (CADM) or those with anti-CADM140/MDA5 antibody are especially prone to develop rapidly progressive interstitial pneumonia. We retrospectively analyzed 46 patients with PM/DM admitted to our hospital and identified DM, rapidly progressive disease, honeycomb lung, CADM and extensive ILD as risk factors for recurrence or death. In the presence of two or more risk factors, the sensitivity and specificity for the prediction of death or relapse were 81.3% and 76.7%, respectively. Calcineurin inhibitors have been widely used as induction and maintenance therapy for PM/DM-associated ILD. Recently we reported the benefit of tacrolimus on the disease-free survival and event-free survival of the patients with PM/DM-associated ILD. Among those patients treated with tacrolimus, poor prognostic factors for death, recurrence or severe adverse event were identified as acute progression of the disease, honeycomb lung, forced vital capacity (FVC) less than 80% and having DM. The potential effectiveness of an intensive therapy protocol with triple therapy that comprises high-dose corticosteroids, calcineurin inhibitors and cyclophosphamide has been reported.

Antiphospholipid scoring: significance in diagnosis and prognosis

Recently our group introduced the “antiphospholipid score” (aPL-S), a quantitative marker that represents aPL profile. We have validated its efficacy for the diagnosis of antiphospholipid syndrome (APS) and predictive value for thrombosis. The study comprised two independent sets of patients with autoimmune diseases. In the first set of patients ( n = 233), the aPL-S was established by analyzing aPL profiles. In the second set of patients ( n = 411), the predictive value of the aPL-S for thrombosis was evaluated. To define aPL-S, we calculated the relative risks (approximated by odds ratios (ORs)) of having APS manifestations (thrombosis and/or pregnancy morbidity) for each of the aPL tests and devised an original formula in which aPL-S was determined by OR: aPL-S = 5 × exp ([OR] −5)/4. The receiver operating characteristic (ROC) curve showed a hyperbolic pattern and the area under the ROC curve value was 0.752 (0.686 for revised Sapporo criteria), implying that aPL-S is a potential quantitative marker for APS diagnosis. The OR for thrombosis in patients with a high aPL-S (≥30) was 5.27 (95% confidence interval (95% CI) 2.32–11.95, p < 0.0001). By multivariate analysis, an aPL-S of ≥30 appeared to be an independent risk factor for thrombosis (hazard ratio 3.144 (95% CI 1.383–7.150), p = 0.006). The aPL-S is a useful quantitative index for diagnosing APS and may be a predictive marker for thrombosis in autoimmune diseases.

[Clinical significance of antiphospholipid antibody measured by EliA anticardiolipin antibodies and anti-β2Glycoprotein I antibodies in antiphospholipid syndrome]

Anticardiolipin antibodies (aCL-IgG/IgM) and anti-β2-glycoprotein I antibodies (aβ2GPI-IgG/IgM) are laboratory tests included in the current classification criteria for definite antiphospholipid syndrome (APS). However, not all of these assays have been commercially available in Japan. We investigated the efficacy of aCL-IgG/IgM and aβ2GPI-IgG/IgM assays using fluorescence enzyme immunoassay (Phadia:EliA(TM)) for the diagnosis of APS in Japan. This study comprised 229 sera from patients (100 with APS and 129 without APS). The diagnosis of APS was made according to Sydney revised Sapporo criteria. EliA(TM)Cardiolipin and EliA(TM)β2-Glycoprotein (Phadia AB. Uppsala Sweden) were used to detect aCL IgG/M and aβ2GPI IgG/M, respectively. Sensitivity, specificity and area under the receiver operating characteristic curve (AUC) were as follows; aCL-IgG (45%, 94%, 0.80), aCL-IgM (20%, 94%, 0.54), aβ2GPI-IgG (33%, 98%, 0.88) and aβ2GPI-IgM (16%, 99%, 0.64) respectively. aCL-IgM, aβ2GPI-IgG or aβ2GPI-IgM were detected in 10 patients (18%) with aCL-IgG negative. The use of Phadia:EliA(TM)antiphospholipid antibodies assays improve the diagnostic yield of thrombotic risk in APS patients.

The involvement of CD36 in monocyte activation by antiphospholipid antibodies

Background

CD36, known as a scavenger receptor, is a transmembrane glycoprotein expressed on monocytes, platelets and endothelial cells, recognizes multiple ligands, including phosphatidylserine, and regulates atherogenesis and thrombosis. The objective of this study is to investigate the possible involvement of CD36 in the pathophysiology of thrombosis in patients with antiphospholipid syndrome (APS).

Methods

First, rs3765187, a missense mutation linked to CD36 deficiency, was investigated by TaqMan polymerase chain reaction (PCR) genotyping method in 819 Japanese, including 132 patients with APS, 265 with systemic lupus erythematosus (SLE) in the absence of APS, and 422 healthy subjects. Then, the involvement of CD36 in antiphospholipid antibody (aPL)-induced tissue factor (TF) expression was examined using CD36-null mice or anti-CD36. Purified IgG from patients with APS and a monoclonal phosphatidylserine-dependent antiprothrombin antibody were used in these experiments. TF expression was tested by real-time PCR and flow cytometry.

Results

Minor allele carrier of rs3765187 was less frequent in patients with APS (3.8% p = 0.032), but not in patients with SLE in the absence of APS (7.9% p = 0.32), compared with healthy subjects (10.2%). The aPL-induced TF expression was significantly suppressed on peritoneal macrophages from CD36-null mice compared to wild type and significantly inhibited by anti-CD36 on human monocytes.

Conclusions

The gene mutation linked to CD36 deficiency was less frequent in patients with APS. The deficient or suppressed CD36 function significantly reduced aPL-induced TF expression in vitro. Taken together, in a susceptible background CD36 scavenger receptor function may be involved in the thrombotic pathophysiology in patients with APS.

Pathophysiology of thrombosis and pregnancy morbidity in the antiphospholipid syndrome

In patients with the antiphospholipid syndrome (APS), the presence of a group of pathogenic autoantibodies called antiphospholipid antibodies causes arteriovenous thrombosis and pregnancy complications. To date, the pathogenicity of the antiphospholipid antibodies has been the focus of analysis. Recently, the antibodies were reported to be capable of direct cell activation, and research on the underlying mechanism is ongoing. The antiphospholipid antibodies bind to the membranes of vascular endothelial cells, monocytes and platelets, provoking tissue factor expression and platelet aggregation. This activation functions as intracellular signalling, independent of the cell type, to activate p38MAPK and the transcription factor NFκB. Currently, there are multiple candidates for the membrane receptors of the antiphospholipid antibodies that are being tested for potential in specific therapy. Recently, APS was reported to have significant comorbidity with complement activation, and it was proposed that this results in placental damage and cell activation and, therefore, could be the primary factor for the onset of pregnancy complications and thrombosis. The detailed mechanism of complement activation remains unknown; however, an inflammation-inducing substance called anaphylatoxin, which appears during the activation process of the classical complement pathway, is thought to be a key molecule. Complement activation occurs in tandem, regardless of the pathology of APS or the type of antiphospholipid antibody, and it is thought that this completely new understanding of the mechanism will contribute greatly to comprehension of the pathology of APS.

Efficacy of the antiphospholipid score for the diagnosis of antiphospholipid syndrome and its predictive value for thrombotic events

OBJECTIVE

To define the antiphospholipid score (aPL-S) by testing multiple antiphospholipid antibodies (aPL) and to evaluate its efficacy for the diagnosis of antiphospholipid syndrome (APS) and predictive value for thrombosis.

METHODS

This study comprised 2 independent sets of patients with autoimmune diseases. In the first set of patients (n = 233), the aPL profiles were analyzed. Five clotting assays for testing lupus anticoagulant and 6 enzyme-linked immunosorbent assays (IgG/IgM anticardiolipin antibodies, IgG/IgM anti-β(2)-glycoprotein I, and IgG/IgM phosphatidylserine-dependent antiprothrombin antibodies) were included. The association of the aPL-S with a history of thrombosis/pregnancy morbidity was assessed. In the second set of patients (n = 411), the predictive value of the aPL-S for thrombosis was evaluated retrospectively. Two hundred ninety-six of these patients were followed up for >2 years. The relationship between the aPL-S and the risk of developing thrombosis was analyzed.

RESULTS

In the first set of patients, the aPL-S was higher in those with thrombosis/pregnancy morbidity than in those without manifestations of APS (P < 0.00001). For the aPL-S, the area under the receiver operating characteristic curve value was 0.752. In the second set of patients, new thromboses developed in 32 patients. The odds ratio (OR) for thrombosis in patients with an aPL-S of ≥30 was 5.27 (95% confidence interval [95% CI] 2.32-11.95, P < 0.0001). By multivariate analysis, an aPL-S of ≥30 appeared to be an independent risk factor for thrombosis (hazard ratio 3.144 [95% CI 1.383-7.150], P = 0.006).

CONCLUSION

The aPL-S is a useful quantitative index for diagnosing APS and may be a predictive marker for thrombosis in autoimmune diseases.

Predominant prevalence of arterial thrombosis in Japanese patients with antiphospholipid syndrome

Objective: To study the clinical and immunological manifestations of antiphospholipid syndrome (APS) in the Japanese population by a single-centre registration. Methods: In this retrospective cohort study, 141 consecutive patients with APS, fulfilling the Sydney revised Sapporo criteria for definite APS, who visited our autoimmune clinic from 1988 to 2010, were recruited and followed up. All the patients were interviewed and underwent a general physical examination by qualified rheumatologists on the day of blood sampling. Results: The population comprised 119 woman and 22 men with a mean age at diagnosis of 44 years (range 9–79 years). Seventy patients (49.6%) had primary APS, and 71 (50.4%) had systemic lupus erythematosus. The prevalence of thrombosis was 85.8 per cent, arterial thrombosis was found in 93 patients (66.0%) and venous thrombosis was found in 46 patients (32.6%). The most common thrombosis was cerebral infarction [86/141 (61.0%)] followed by deep vein thrombosis [33/141 (23.4%)]. Among 70 pregnant women, 45 (64.3%) had obstetric complications. Lupus anticoagulant was detected in 116 patients (82.3%), anticardiolipin antibodies in 83 (58.9%), anti-β2 glycoprotein I antibodies in 73 (51.8%) and phosphatidylserine-dependent antiprothrombin antibodies in 98 (69.5%). Conclusion: High prevalence of arterial thrombosis was noted in Japanese patients with APS. The profile of heterogeneous and complex clinical manifestations was substantiated in Japanese patients with APS.

Phospholipid scramblase 1 expression is enhanced in patients with antiphospholipid syndrome

OBJECTIVE

Thrombus formation is the key event of vascular manifestations in antiphospholipid syndrome (APS). Phosphatidylserine (PS) is normally sequestered in the inner leaflet of cell membranes. Externalization of PS occurs during cell activation and is essential for promoting blood coagulation and for the binding of antiphospholipid antibodies (aPL) to cells. One of the molecules involved in PS externalization is phospholipid scramblase 1 (PLSCR1). We evaluated PLSCR1 expression on monocytes from APS patients and analyzed the in vitro effect of monoclonal aPL on PLSCR1 expression.

PATIENTS AND METHODS

Forty patients with APS were investigated. In vitro experiments were performed in monocyte cell lines incubated with monoclonal aPL. PLSCR1 expression was determined by quantitative real-time polymerase chain reactions. PS exposure on CD14(+) cell surface was analyzed by flow cytometry.

RESULTS

Levels of full-length PLSCR1 messenger RNA (mRNA) were significantly increased in APS patients compared with healthy controls (2.4 ± 1.2 vs. 1.3 ± 0.4, respectively, p < 0.001). In cultured monocytes, interferon alpha enhanced tissue-factor expression mediated by β2-glycoprotein-I-dependent monoclonal anticardiolipin antibody.

CONCLUSIONS

Monocytes in APS patients had increased PLSCR1 mRNA expression.

'Non-criteria' aPL tests: report of a task force and preconference workshop at the 13th International Congress on Antiphospholipid Antibodies, Galveston, TX, USA, April 2010

Abstract: Current classification criteria for definite APS recommend the use of one or more of three positive standardized laboratory assays, including anticardiolipin antibodies (aCL), lupus anticoagulant (LA), and antibodies directed to β(2)glycoprotein I (anti-β(2)GPI) to detect antiphospholipid antibodies (aPL) in the presence of at least one of the two major clinical manifestations (i.e., thrombosis or pregnancy morbidity) of the syndrome. Several other autoantibodies shown to be directed to phospholipids and/or their complexes with phospholipids and/or to proteins of the coagulation cascade, as well as a mechanistic test for resistance to annexin A5 anticoagulant activity, have been proposed to be relevant to APS. A task force of worldwide scientists in the field discussed and analyzed critical questions related to 'non-criteria' aPL tests in an evidence-based manner during the 13th International Congress on Antiphospholipid Antibodies (APLA 2010, 13-16 April 2010, Galveston, Texas, USA). This report summarizes the findings, conclusions, and recommendations of this task force.

Increased expression of phospholipid scramblase 1 in monocytes from patients with systemic lupus erythematosus

OBJECTIVE

A high incidence of thromboembolic events has been reported in patients with systemic lupus erythematosus (SLE). Phosphatidylserine (PS) is normally sequestered in the inner leaflet of cell membranes. Externalization of PS during cell activation is mediated by phospholipid scramblase 1 (PLSCR1) and has a central role in promoting blood coagulation. We investigated the underlying pathogenic status of thrombophilia in SLE by analyzing PLSCR1 expression on monocytes from patients with SLE.

METHODS

Sixty patients with SLE were evaluated. Twenty-three patients had antiphospholipid syndrome (APS/SLE). Plasma D-dimer levels were measured as a marker of fibrin turnover. The cDNA encoding human PLSCR1 was cloned from the total RNA extract from monocytes, and independent clones were sequenced. PLSCR1 mRNA expression in CD14+ cells was determined by real-time polymerase chain reaction. PS exposure on CD14+ cell surface was analyzed by flow cytometry.

RESULTS

Elevated D-dimer levels were found in plasma from SLE patients. Three splice variants of PLSCR1 mRNA were identified in all subjects, and levels of full-length PLSCR1 mRNA were significantly increased in SLE compared to healthy controls (2.9 +/- 1.5 vs 1.3 +/- 0.4, respectively; p < 0.0001). Flow-cytometry analysis showed relative enhancement of PS exposure in the surface of CD14+ cells in SLE patients compared to healthy controls.

CONCLUSION

Novel PLSCR1 splice variants were identified. Monocytes in SLE patients had enhanced PLSCR1 mRNA expression, as well as increased fibrin turnover and cell-surface PS exposure, indicating that PLSCR1 may, in part, contribute to the prothrombotic tendency in SLE.

Anti-beta2 glycoprotein-I antibody increases the risk of pregnancy-induced hypertension: a case-controlled study

The aim of this study was to evaluate whether anti-beta2 glycoprotein-I antibody (anti-beta2GPI) of the IgG or IgM classes is associated with the development of pregnancy-induced hypertension (PIH) or preeclampsia in the Japanese population. In a case-controlled cohort study, peripheral blood was obtained at 8-14 weeks of gestation from a consecutive series of 1155 women. The case group comprised 36 patients who later developed PIH during the pregnancy. Of the 36 PIH patients, 13 had severe PIH, 18 had preeclampsia and 11 had severe preeclampsia. One hundred and eleven age- and parity-matched women whose pregnancies ended in normal delivery without obstetric complications were selected as controls. We found that a titer of anti-beta2GPI IgG>or=1.0 U/ml was a risk factor for severe PIH (P=0.023, OR 5.7 95%CI 1.4-22.8). In addition, titers of anti-beta2GPI IgM>or=1.2 U/ml was found to be a risk factor for PIH (P=0.001, OR 8.8 95%CI 1.6-47.5). In women positive for anti-beta2GPI but negative for lupus anticoagulant, anti-cardiolipin, phosphatidylserine-dependent anti-prothrombin, or kininogen-dependent anti-phosphatidylethanolamine antibodies, the presence of anti-beta2GPI was not a significant risk factor for development of PIH or preeclampsia. In conclusion, the presence of anti-beta2GPI antibody represents a risk factor for developing PIH and severe PIH. This finding supports the utility of anti-beta2GPI determination as one of the laboratory criteria for anti-phospholipid syndrome classification. The usefulness of anti-beta2GPI measurement among women without other anti-phospholipid antibodies requires further study.

Complement activation in patients with primary antiphospholipid syndrome

OBJECTIVE

To investigate the significance of complement activation in patients with primary antiphospholipid syndrome (APS).

METHODS

Thirty-six patients with primary APS, 42 control patients with non-systemic lupus erythematosus (SLE) connective tissue diseases, and 36 healthy volunteers were analysed retrospectively. Serum complement levels (C3, C4, CH(50)) and anaphylatoxins (C3a, C4a, C5a) were examined in all subjects, and serum complement regulatory factors (factor H and factor I) were measured in patients with primary APS. Plasma anticoagulant activity was determined in a mixing test using the activated partial thromboplastin time.

RESULTS

Serum complement levels were significantly lower in patients with primary APS than in patients with non-SLE connective tissue diseases (mean (SD) C3: 81.07 (17.86) vs 109.80 (22.76) mg/dl, p<0.001; C4: 13.04 (8.49) vs 21.70 (6.96) mg/dl, p<0.001; CH(50): 31.32 (8.76) vs 41.40 (7.70) U/ml, p<0.001) or healthy volunteers. Only two healthy subjects with low serum C4 levels showed hypocomplementaemia, whereas most patients with primary APS showed raised serum C3a and C4a. No subjects showed raised C5a. Patients with primary APS with low serum C3 or C4 had significantly higher levels of C3a or C4a than healthy controls. No patients had low serum complement regulatory factors. Among patients with primary APS, hypocomplementaemia was significantly more common in those with high anticoagulant activity than in those with low or normal activity.

CONCLUSION

Hypocomplementaemia is common in patients with primary APS, reflecting complement activation and consumption, and was correlated with anticoagulant activity, suggesting that antiphospholipid antibodies may activate monocytes and macrophages via anaphylatoxins produced in complement activation.

Thrombotic microangiopathy in patients with phosphatidylserine dependent antiprothrombin antibodies and antiphospholipid syndrome

Thrombotic microangiopathy (TMA) is a rare disorder characterized by microvascular thrombosis. TMA has been reported in patients with antiphospholipid antibodies and/or antiphospholipid syndrome but its pathogenesis is not clarified. We present two patients with TMA associated with IgG phosphatidylserine dependent antiprothrombin antibodies (aPS/PT). CASE 1: A 44-year-old Japanese female with systemic lupus erythematosus (SLE) and positive lupus anticoagulant (LA) was started on ticlopidine after having stroke. Four weeks later she developed TMA. IgG/M/A anticardiolipin antibodies (aCL) were negative, but strong positive IgG aPS/PT were detected. CASE 2: A 32-year-old Russian female with SLE was admitted because of hypertension, renal insufficiency and proteinuria at 14 weeks of pregnancy. She developed TMA after surgical abortion. IgG aPS/PT and LA were strongly positive but IgG/M/A aCL were negative. Neither case had von Willebrand factor cleaving protease (ADAMTS-13), suggesting that TMA in those patients was associated with thrombophilia rather than insufficient ADAMTS-13. Both patients were successfully treated with a series of plasma exchange.

Antiphospholipid antibodies: lessons from the bench

Antiphospholipid antibodies (aPL) are an heterogeneous group of circulating immunoglobulins arising in a wide range of infectious and autoimmune diseases. Since the early 80s, the interest on anticardiolipin antibodies (aCL) has exponentially increased due to their association with thrombosis. The antiphospholipid syndrome (APS) was defined as a clinical disorder characterized by thrombosis and pregnancy morbidity associated to the persistent presence of aCL and/or lupus anticoagulant (LA). Thrombosis is the major manifestation in patients with aPL, but the spectrum of symptoms and signs associated with aPL has considerably broadened, and other manifestations such as thrombocytopenia, non-thrombotic neurological syndromes, psychiatric manifestations, livedo reticularis, skin ulcers, haemolytic anemia, pulmonary hypertension, cardiac valve abnormality and atherosclerosis have also been related to the presence of those antibodies. Numerous mechanisms have been proposed to explain the thrombotic tendency of patients with aPL, but the pathogenesis seems to be multifactorial.

Research around beta 2-glycoprotein I: a major target for antiphospholipid antibodies

Beta2-glycoprotein I (beta2GPI), a phospholipid-binding protein, is one of the major target antigens for antiphospholipid antibodies (aPL) found in patients with antiphospholipid syndrome (APS). Thrombophilic disorders in APS patients are strongly associated with aPL, and their pathogenic properties depend on the presence of beta2GPI. Procoagulant cell stimulation by aPL, via beta2GPI, is one of the most plausible mechanisms of thrombosis in APS, and p38 mitogen activated protein kinase (MAPK) pathway plays a crucial role in such activation. beta2GPI is proteolytically cleaved in domain V by activated factor X or plasmin, leading to the generation of the nicked form of beta2GPI. Recently, increasing attention is focused on the role of nicked-beta2GPI as a regulator of extrinsic fibrinolysis pathway.

Association of HLA-DM polymorphism with the production of antiphospholipid antibodies

OBJECTIVE

To investigate whether variation in the HLA-DM gene is important in producing a group of pathogenic autoantibodies-antiphospholipid antibodies (aPL)-on the basis that HLA class II restricted antigen presentation is involved in the production of aPL.

METHODS

HLA-DMA and DMB polymorphisms were genotyped by polymerase chain reaction combined with restriction enzyme digestion in 51 white patients with primary antiphospholipid syndrome (APS), 82 with systemic lupus erythematosus (SLE) (42 with APS and 40 without APS), and 109 healthy white controls. The association with the aPL profile was examined.

RESULTS

The distribution of DMA alleles in APS patients and in patients with APS associated with SLE was significantly different from that in controls by 4x2 chi(2) test with 3 degrees of freedom (p = 0.035 and 0.011, respectively), but it was not different between SLE patients without APS and controls. The allelic distribution of DMA was also different between patients with IgG class anticardiolipin antibody or those with lupus anticoagulant (LA) and controls (p = 0.012 and 0.007, respectively) and between patients with and without LA among SLE patients (p = 0.035). All these differences included the increase in DMA*0102 in the former groups.

CONCLUSIONS

The results suggest that HLA-DMA*0102 or its linked gene(s) form one of the genetic risks for the production of aPL.

The p38 mitogen-activated protein kinase (MAPK) pathway mediates induction of the tissue factor gene in monocytes stimulated with human monoclonal anti- 2Glycoprotein I antibodies

The anti-phospholipid syndrome (APS) is characterized by thrombosis and the presence of anti-phospholipid antibodies (aPL). Tissue factor (TF), the major initiator of the coagulation system, is induced on monocytes by aPL in vitro, explaining, in part, the pathophysiology in this syndrome. However, little is known regarding the nature of the aPL-induced signal transduction pathways leading to TF expression. In this study, we investigated aPL-inducible genes in PBMC using cDNA array system and real-time PCR. Our results indicated that the mitogen-activated protein kinase (MAPK) pathway was related to TF expression when PBMCs were treated, in the presence of beta(2)Glycoprotein I (beta(2)GPI), with human monoclonal anti-beta(2)GPI antibodies [beta(2)GPI-dependent anti-cardiolipin antibodies (aCL/beta(2)GPI)]. Western blotting studies using monocyte cell line (RAW264.7) demonstrated that p38 MAPK protein was phosphorylated with nuclear factor kappaB (NF-kappaB) activation by monoclonal aCL/beta(2)GPI treatment, and that SB203580, a specific p38 MAPK inhibitor, decreased the aCL/beta(2)GPI-induced TF mRNA expression. The p38 MAPK phosphorylation, NF-kappaB translocation and TF mRNA expression triggered by aCL/beta(2)GPI were abolished in the absence of beta(2)GPI. These results demonstrated that the p38 MAPK signaling pathway plays an important role in aPL-induced TF expression on monocytes and suggest that the p38 MAPK may be a possible therapeutic target to modify a pro-thrombotic state in patients with APS.

Antiprothombin antibodies and the diagnosis of antiphospholipid syndrome

The preliminary classification criteria for definite antiphospholipid syndrome (APS) include the presence of anticardiolipin antibodies (aCL) and/or lupus anticoagulant (LA) as laboratory criteria. However, antiphospholipid antibodies (aPL) are a heterogeneous group of antibodies comprising also antibodies against phospholipid-binding proteins or their complexes with phospholipids. Prothrombin is one of the antigen recognized by aPL. In the last decade, there has been increasing interest in antibodies against prothrombin alone and those against phosphatidylserine-prothrombin complex. The latter, phosphatidylserine-dependent antiprothrombin antibodies (aPT), have been closely associated with APS and LA. In this paper, we review the properties of antiprothrombin antibodies.

Diagnostic value of antiagalactosyl IgG antibodies in rheumatoid arthritis

Our objective in this study was to explore the diagnostic value of antiagalactosyl IgG antibodies in rheumatoid arthritis (RA). The study comprised 266 Japanese patients with systemic autoimmune diseases, including 60 with RA. Human agalactosyl IgG was prepared enzymatically, and the serum levels of antiagalactosyl IgG antibodies were determined using a lectin enzyme immunoassay. Serum IgG and IgM rheumatoid factors (RF) were measured using laser nephelometry for IgM (LN-RF) and an enzyme-linked immunosorbent assay for IgG (IgG-RF). Antiagalactosyl IgG antibodies were significantly more common in patients with RA than in those without (78% vs. 18%, odds ratio (OR) 16.51, 95% confidence interval (CI) 8.12-33.58, p<0.0001). Patients with RA also had a higher frequency of LN-RF than those without RA (75% vs. 28%, OR 7.81, 95% CI 3.91-15.58, p< 0.001). The specificity of antiagalactosyl IgG antibodies for RA was significantly higher than that of LN-RF (82% vs. 72%, p<0.0011). There was a significant correlation between titers of antiagalactosyl IgG antibodies and C-reactive protein levels. Antiagalactosyl IgG antibodies are more specific markers for RA than conventional LN-RF, and may provide useful information for the diagnosis of RA.

Nicked beta2-glycoprotein I: a marker of cerebral infarct and a novel role in the negative feedback pathway of extrinsic fibrinolysis

BEta(2)-glycoprotein I (beta(2)-GPI) is proteolytically cleaved by plasmin in domain V (nicked beta(2)-GPI), being unable to bind to phospholipids. This cleavage may occur in vivo and elevated plasma levels of nicked beta(2)-GPI were detected in patients with massive plasmin generation and fibrinolysis turnover. In this study, we report higher prevalence of elevated ratio of nicked beta(2)-GPI against total beta(2)-GPI in patients with ischemic stroke (63%) and healthy subjects with lacunar infarct (27%) when compared to healthy subjects with normal findings on magnetic resonance imaging (8%), suggesting that nicked beta(2)-GPI might have a physiologic role beyond that of its parent molecule in patients with thrombosis. Several inhibitors of extrinsic fibrinolysis are known, but a negative feedback regulator has not been yet documented. We demonstrate that nicked beta(2)-GPI binds to Glu-plasminogen with K(D) of 0.37 x 10(-6) M, presumably mediated by the interaction between the fifth domain of nicked beta(2)-GPI and the fifth kringle domain of Glu-plasminogen. Nicked beta(2)-GPI also suppressed plasmin generation up to 70% in the presence of tissue plasminogen activator, plasminogen, and fibrin. Intact beta(2)-GPI lacks these properties. These data suggest that beta(2)-GPI/plasmin-nicked beta(2)-GPI controls extrinsic fibrinolysis via a negative feedback pathway loop.

Antiprothrombin antibodies—are they worth assaying?

According to the preliminary classification criteria of the antiphospholipid syndrome (APS) (Sapporo Criteria), beta2-glycoprotein I (beta2GPI)-dependent anticardiolipin antibodies (aCL) and lupus anticoagulant (LA) are the only laboratory tests considered as criteria for the classification of the APS. Recently, antibodies against phosphatidylserine-prothrombin complex (aPS/PT) have been detected and these antibodies, rather than antibodies against prothrombin alone, are closely associated with APS and LA. We assessed the sensitivity and specificity of aPS/PT for the diagnosis of APS in our population of patients with a variety of autoimmune disorders and investigated whether aPS/PT could be used as diagnostic test in patients suspected of having APS. The study population comprised 219 patients with autoimmune diseases including 82 patients with APS and 137 without APS (55 systemic lupus erythematosus, 32 rheumatoid arthritis, 10 primary Sjogren's syndrome, 8 scleroderma, 5 Behcet's disease and 27 other rheumatic diseases). IgG/M aPS/PT were measured by ELISA using phosphatidylserine-prothrombin complex as antigen immobilized on ELISA plates in the presence of CaCl2. IgG/M aCL were measured by standard methods and LA was detected by clotting assays. aPS/PT, aCL and LA were more frequently found in patients with APS (47, 46 and 69, respectively) than in those without APS (11, 19 and 29, respectively) (OR 95% [CI]; 15.4 [7.2-32.7], 7.9 [4.1-15.2, 19.8 [9.6-40.6], respectively]. The sensitivity of each assay for the diagnosis of APS was 57%, 56% and 86% with a specificity of 92%, 86% and 79%, respectively. aPS/PT and aCL have similar diagnostic value for APS, therefore, we propose that aPS/PT should be further explored, not only for research purposes, but also as a candidate of one of the laboratory criteria for the classification of the APS.

Cerebral imaging by magnetic resonance imaging and single photon emission computed tomography in systemic lupus erythematosus with central nervous system involvement

OBJECTIVE

To assess the significance of magnetic resonance imaging (MRI) and single photon emission computed tomography (SPECT) abnormalities in patients with systemic lupus erythematosus (SLE).

METHODS

Forty-four patients with SLE were retrospectively analysed. Patients were classified into three groups [1 and 2: patients with central nervous system (CNS) manifestations before and after starting high-dose steroid therapy, respectively; 3: patients without CNS manifestations. MRI was performed in all 44 patients and SPECT in 31.

RESULTS

Abnormal findings in MRI were found in 19 patients. MRI abnormalities were significantly more frequent in patients with CNS manifestations than in those without [71 vs 17%, odds ratio (OR) 11.9, confidence interval (CI) 2.8-49.9, P=0.0003]. After the initiation of steroid therapy, patients with CNS manifestations also had an increased frequency of abnormal MRI. No correlation was found between SPECT findings and CNS manifestations. However, patients with CNS manifestations after starting steroids showed a markedly increased frequency of abnormal MRI and SPECT compared with those without CNS manifestations (80 vs 7%; OR 56, CI 4.4-719, P=0.0003). The positive predictive value of abnormality in both techniques in developing CNS manifestations after starting steroids was 89%.

CONCLUSION

MRI findings correlated with CNS manifestations in SLE. Where there is a high suspicion of CNS involvement, the combination of MRI and SPECT may be useful in predicting CNS manifestations after starting steroid therapy.

HLA class II gene polymorphisms in antiphospholipid syndrome: haplotype analysis in 83 Caucasoid patients

OBJECTIVES

We investigated the association between HLA class II haplotypes and antiphospholipid syndrome (APS).

METHODS

HLA DRB1, DQB1 and DQA1 genotypes were determined by the polymerase chain reaction using sequence-specific primers in 83 Caucasoid British patients with APS. The genotype frequencies were compared between subgroups of patients and 177 healthy controls.

RESULTS

DQB1*0604/5/6/7/9-DQA1*0102-DRB1*1302 and DQB1*0303-DQA1*0201-DRB1*0701 haplotypes showed significantly positive correlations with APS [P=0.0087 and P=0.0012, respectively]. The association of the former was enhanced in primary APS patients with anti-beta 2-glycoprotein I antibodies (anti-beta 2GPI) [odds ratio 6.2, 95% confidence interval (2.2-17.6), P=0.0014, corrected P=0.042].

CONCLUSIONS

These alleles and haplotypes might affect anti-ss2GPI production and APS development in different and heterogeneous fashion.

Antiphospholipid antibodies in leprotic patients: a correlation with disease manifestations

OBJECTIVES

Previous studies showed that antiphospholipid antibodies (aPL) are frequent in the sera of leprosy patients and are most probably directed against body tissue cardiolipins. Some groups have demonstrated differences between the binding specificity of "autoimmune-aPL" and "non-autoimmune-aPL". It is widely accepted that a plasma protein, beta 2-Glycoprotein I (beta 2-GPI), is required for the binding of autoimmune anticardiolipin antibodies (aCL) to cardiolipin. However, some reports suggested heterogeneity of leprosy aCL with respect to their beta 2-Glycoprotein I (beta 2GPI) dependency, although no thromboembolic complications have been reported. This study was designed to assess the specificity of aPL by investigating the prevalence of aCL, anti-phosphatidylserine (aPS), anti-phosphatidylinositol (aPI), anti-beta 2GPI and antiprothrombin (aPT) antibodies, and evaluate their clinical significance in a group of patients with lepromatous leprosy.

PATIENTS AND METHODS

35 lepromatous leprosy patients were selected randomly from an Egyptian leprosarium as a study group. 35 normal household contact controls were selected matching the study group for both sex and age. aCL, aPS, aPI, aPT, anti-beta 2GPI and beta 2-dependent aCL antibodies were investigated by ELISA in all patients and controls.

RESULTS

aCL antibodies were more frequent in leprosy patients than in controls [13/35 (37%) vs. 3/35 (9%), respectively, p = 0.02] and significantly correlated with Raynaud's phenomenon, skin nodules, chronic skin ulcers and urticarial skin rash. No association was found with hypopigmentation, hyperpigmentation and saddle nose. None of the patients presented aPS nor aPI. Only 1 subject from the control group presented aPI along with aCL. aPT were present in 2/35 (5.7%) and anti-beta 2GPI in 1/35 (2.9%) leprotic patients. None of the individuals from the control group presented aPT nor anti-beta 2GPI.

CONCLUSIONS

An association was found between the presence of aCL and certain dermatological manifestations of leprosy, such as Raynaud's phenomenon, skin nodules, chronic skin ulcers and urticarial skin rash. As in other infectious diseases, there was a lack of beta 2GPI-dependency and an absence of thrombotic complications.

Association of antiphosphatidylserine/prothrombin autoantibodies with HLA class II genes

OBJECTIVE

To investigate the associations between HLA class II genes and antiphosphatidylserine/prothrombin antibodies (aPS/PT) in a group of British caucasoid patients with antiphospholipid antibodies (aPL).

METHODS

This study included 82 patients with aPL. IgG aPS/PT were detected in sera using enzyme-linked immunosorbent assays. HLA-DQB1, DQA1, and DRB1 genotypes were determined by polymerase chain reaction using sequence-specific primers. All results were compared with 177 matched healthy control subjects.

RESULTS

IgG aPS/PT were present in 41 of 82 patients (50%). The frequencies of DQB1*0301/4, DQB1*0604/5/6/7/9, and DRB1*1302 alleles were increased in patients with aPS/PT compared with controls. To minimize the interference of the association between anti-beta2-glycoprotein I (anti-beta2GPI) and HLA, patients with anti-beta2GPI were excluded from further analyses, and only HLA-DQB1*0301/4 remained significant compared with controls (odds ratio [OR] 2.75, 95% confidence interval [95% CI] 1.2-6.5, P < 0.03). In the haplotype analysis, HLA-DQB1*0301/4;DQA1* 0301/2;DRB1*04 was significantly increased in patients with IgG aPS/PT compared with controls (OR 4.75, 95% CI 1.72-13.10, P = 0.0063).

CONCLUSION

The HLA-DQB1*0301/4;DQA1*0301/ 2;DRB1*04 haplotype and its components may influence the production of aPS/PT in the antiphospholipid syndrome, which partly explains the correlation between the lupus anticoagulant and DQB1*03.

Autoantibodies against malondialdehyde-modified lipoprotein(a) in antiphospholipid syndrome

OBJECTIVE

To demonstrate the existence of antibodies that react against malondialdehyde (MDA)-modified lipoprotein(a) (MDA-Lp[a]), a molecule that exhibits behavioral similarities to MDA-modified low-density lipoprotein (MDA-LDL), and to assess the possible relationship of these antibodies (anti-MDA-Lp[a]) to anti-MDA-LDL antibodies (anti-MDA-LDL) in the antiphospholipid syndrome (APS).

METHODS

We studied 104 patients with APS (61 with primary APS and 43 with APS secondary to systemic lupus erythematosus) and 106 healthy controls. Anti-MDA-Lp(a) were measured by enzyme-linked immunosorbent assay (ELISA) using MDA-Lp(a) as antigen. Plasma levels of Lp(a) were determined. Anti-MDA-LDL, anticardiolipin antibodies (aCL), and anti-beta2-glycoprotein I antibodies (anti-beta2GPI) were also measured by ELISA. Inhibition assays were performed to determine the presence of cross-reactivity between anti-MDA-Lp(a) and anti-MDA-LDL.

RESULTS

Anti-MDA-Lp(a) were detected in 38 of 104 patients (37%) but in only 6 of 106 controls (6%) (chi2 = 28, P<0.0001). Levels of anti-MDA-Lp(a) were also higher in patients than in controls (P<0.0001). Titers of these antibodies did not correlate with plasma levels of Lp(a). The presence of anti-MDA-Lp(a) was significantly associated with that of anti-MDA-LDL (chi2 = 22.09, P<0.0001). There was a strong correlation between the titers of anti-MDA-Lp(a) and anti-MDA-LDL (r = 0.59, P<0.0001), and inhibition assays showed significant cross-reactivity between the 2 populations of antibodies. Anticardiolipin antibodies and anti-beta2GPI were present in sera from 67 patients (64%) and 48 patients (46%), respectively. No correlation was found between the titer of anti-MDA-Lp(a) and titers of either aCL or anti-beta2GPI.

CONCLUSION

We report for the first time the existence of autoantibodies against MDA-Lp(a). The presence of antibodies reacting not only against MDA-LDL but also against MDA-Lp(a) supports the hypothesis of a role for oxidative phenomena in the pathogenesis of APS and atherosclerosis.

Correlation between beta2-glycoprotein I valine/leucine247 polymorphism and anti-beta2-glycoprotein I antibodies in patients with primary antiphospholipid syndrome

OBJECTIVES

Beta2-Glycoprotein I (beta2GPI) exon 7 polymorphism leads to a valine leucine amino acid exchange at position 247 in domain 5 of beta2GPI, between the phospholipid binding site and the cryptic site of the epitopes for anti-beta2GPI antibodies. Therefore, position 247 polymorphism may affect the conformational change of beta2GPI and the exposure of the epitopes for anticardiolipin antibodies (aCL) (= anti-beta2GPI antibodies). In this study we analysed the genetic polymorphism of beta2GPI in a British cohort of well-defined antiphospholipid syndrome (APS) patients.

METHODS

This study comprised 88 Caucasoid patients with APS [57 with primary APS and 31 with APS secondary to systemic lupus erythematosus (SLE)]. Polymorphism assignment was determined by polymerase chain reaction followed by allele-specific restriction enzyme digestion (PCR-RFLP). The presence of anti-beta2GPI antibodies was detected by ELISA utilizing irradiated ELISA plates.

RESULTS AND CONCLUSIONS

Anti-beta2GPI antibodies were present in 28 of 57 primary APS patients (49%) and in 19 of 31 secondary APS patients (61%). The allele containing valine247 was significantly more frequent in primary APS patients with anti-beta2GPI antibodies than in controls (OR = 2.51, 95%, CI 1.03-6.13, P = 0.0396) or in primary APS patients without anti-beta2GPI antibodies (OR = 2.92, 95% CI 1.16-7.39, P = 0.0204). This tendency was not found in the secondary APS group. In conclusion, the beta2GPI polymorphism, valine/leucine247, is correlated with anti-beta2GPI antibody production in patients with primary APS, and valine247 may be important in the formation of beta2GPI antigenicity.

Risk of thrombosis in patients with antiphospholipid antibodies and factor V Leiden mutation

OBJECTIVE

Antiphospholipid antibodies (aPL) are thrombophilic risk markers in patients with systemic lupus erythematosus (SLE) or primary antiphospholipid syndrome (APS). The risk factors for recurrent venous or arterial thrombosis and indications for longterm anticoagulation therapy are debated. We hypothesized that carrying a second thrombophilic defect, factor V Leiden mutation, would increase the risk for thrombosis in patients with aPL.

METHODS

Seventy-five patients with primary APS and 83 with SLE and aPL with or without thrombosis followed at 2 university hospitals were studied. Factor V mutation rate was analyzed in patients and in 200 healthy blood donors by polymerase chain reaction analysis.

RESULTS

The prevalence of factor V Leiden mutation in patients with SLE and aPL or primary APS was similar to controls. Patients with deep vein thrombosis or arterial thrombosis did not have a significantly increased rate of factor V mutation compared to controls or to patients with aPL without thrombosis.

CONCLUSION

Factor V Leiden mutation is not significantly associated with vein thrombosis in patients with aPL. However, due to the sample size we cannot rule out synergy between both factor V Leiden and aPL. A trend toward increased risk for thrombosis was detected in patients with the mutation and this should be analyzed in a larger study.

Multiple antiphospholipid tests do not increase the diagnostic yield in antiphospholipid syndrome

The family of antiphospholipid antibodies (aPL) includes a heterogeneous population of autoantibodies whose specificity is directed against not only phospholipids, but their complex with plasma proteins. Anticardiolipin antibodies (aCL) and lupus anticoagulant (LA) tests are widely performed to screen the aPL family which is associated with thrombotic complications in patients with systemic lupus erythematosus (SLE) or antiphospholipid syndrome (APS). The clinical significance of other aPL tests, including antibodies against phosphatidylserine (aPS), phosphatidylinositol (aPI), phosphatidic acid (aPA), phosphatidylcholine (aPC) and phosphatidylethanolamine (aPE), has not been established. The purpose of this study was to evaluate whether multiple aPL tests have enhanced diagnostic value for APS. We tested IgG/M/A aPS, aPI, aPA, aPC and aPE by ELISA using 10% bovine serum as blocking and sample diluent in 26 SLE patients with clinical manifestations of APS, but negative for both aCL and LA (Group 1). The results were compared with 32 SLE patients without any features of APS (Group 2) and 24 SLE patients with APS (aCL and/or LA positive) (Group 3). In Group 1, 1/26 (4%) was positive for IgA aPE, less frequent than in other groups, and none of the patients had any other aPL. In Group 2, 1/32 (3%) was positive for aPS, two (6%) for aPI, one (3%) for aPA and four (12.5%) for aPE. None was positive for aPC. In the third group, 13/24 (54%) were positive for aPS, 11 (46%) for aPI, 15 (63%) for aPA, four (17%) for aPC and seven (29%) for aPE. Since aPE was found in some patients, we extended the study, including 207 SLE patients, and tested aPE. IgG/M/A aPE was found in six (3%), 10(5%) and 21 (10%), respectively, but no association was found between aPE and any clinical features of APS. This study suggests that screening by multiple aPL tests does not increase the diagnostic yield in APS.

Antibodies to beta2-glycoprotein I: a potential marker for clinical features of antiphospholipid antibody syndrome in patients with systemic lupus erythematosus

OBJECTIVE

To clarify risk factors for the development of clinical features of antiphospholipid syndrome (APS) in patients with anticardiolipin antibodies (aCL) in systemic lupus erythematosus (SLE).

METHODS

We studied 65 SLE patients, all with positive IgG and/or IgM aCL. Patients were divided into 2 groups; I: 29 SLE patients with features of APS (SLE/APS) and II: 36 aCL positive SLE patients without any feature of APS (SLE/aCL). Serum samples were collected from our serum bank. Anti-beta2-glycoprotein I (anti-beta2-GPI) were tested by ELISA using irradiated plates in the absence of cardiolipin. Anti-dsDNA antibodies were tested by standard Farr assay.

RESULTS

There were no major differences between SLE clinical manifestations in both groups. However, the frequency of IgG anti-beta2-GPI was markedly increased in SLE/APS (18/29, 62%) than in SLE/aCL (4/36, 11%) (chi-squared 18.6, p=0.0001). The levels of anti-dsDNA antibodies in the same samples were slightly lower in SLE/APS.

CONCLUSION

Our data suggest that increased levels of IgG anti-beta2-GPI may be a specific feature of SLE/APS patients rather than reflecting a polyclonal B cell activation.