Novel antiphospholipid antibodies in autoimmune bullous diseases.

BACKGROUND: Pemphigus and bullous pemphigoid are two autoimmune diseases that have similar pathogenesis. Both have a genetic predisposition, which promotes the production of auto antibodies targeted against different components of the epidermal desmosome and hemidesmosome. Antiphospholipid antibodies (aPL) are heterogeneous group of antibodies found in patients with autoimmune diseases and inflammatory conditions and are associated with thrombotic events. OBJECTIVE: We sought to determine the expression profile of eight non classical aPLs in ABD patients. METHODS: A cohort of 266 serum samples of patients with pemphigus, bullous pemphigoid and controls was screened for the presence of eight aPL antibodies, using the Bio-Rad BioPlex™ 2200 system. RESULTS: Phosphatidylserine-beta-2-glycoprotein-I (aPS-ß2GPI) and anti prothrombin complex (aPT-PT) serum profiles were significantly more prevalent among ABD patients; 20.7% patients with ABD compared to 5.9% of control patients were positive for aPS-ß2GPI IgM. In addition, aPT-PT IgM was more prevalent among ABD patients (31% vs. 14.8%). CONCLUSION: aPL auto antibodies are more prevalent in ABD. Any clinical association should be further determined.

Are immunoglobulin A anti-gliadin antibodies helpful in diagnosing coeliac disease in children younger than 2 years?

The usefulness of immumoglobulin (Ig) A antibodies to gliadin (AGA-IgA) in addition to IgA anti-endomysium and tissue transglutaminase antibodies was evaluated in 4122 children younger than 2 years with a suspicion of coeliac disease (CD). Eight percent (312/4122) displayed IgA anti-endomysium and/or IgA anti-tissue transglutaminase, whereas 2.1% (85/4122) displayed only AGA-IgA. Clinical data were obtained for 62 of 85 children with isolated AGA-IgA, and 33 children underwent a duodenal biopsy. Histologically proven CD was established for 5 patients, whereas 57 children were diagnosed to experience other diseases. The systematic detection of AGA-IgA using native gliadin conferred no additional diagnostic benefit for the diagnosis of CD in children younger than 2 years of age, except for rare cases.

Autoimmune bullous diseases the spectrum of infectious agent antibodies and review of the literature.

Pemphigus and bullous pemphigoid are two autoimmune diseases that have a similar pathogenesis. Both have a genetic predisposition which promotes the production of auto-antibodies targeted against different components of the epidermal desmosome and hemidesmosome. Environmental factors play an important role in the pathogenesis of this autoimmune disease. Among these, the role of infectious agents was debated as a causative factor. We sought to determine a possible connection between various infectious agents and autoimmune bullous disease (ABD). A cohort of 148 serum samples of patients with pemphigus, bullous pemphigoid and controls was screened for evidence of a prior infection with HBV, HCV, EBV, CMV, Helicobacter pylori, Toxoplasma gondii and Treponema pallidum, utilizing the Bio-Rad BioPlex 2200 system as well as ELISA assays to complete the panel. HBV, HCV, H. pylori, T. gondii and CMV were demonstrated to have significantly higher prevalence of antibodies in patients with pemphigus and bullous pemphigoid in comparison to controls. Among them, we found a novel association between H. pylori and ABD. Our study suggests a contributing role for HBV, HCV, H. pylori, T. gondii and CMV in inducing ABD in the genetically susceptible host.

Is testing for antiphosphatidylethanolamine antibodies clinically useful?

One of the most intriguing characteristics of the antiphospholipid syndrome (APS) is that diagnosis requires the combined presence of clinical abnormalities (thrombosis and/or miscarriages) and at least one of the following antiphospholipid antibodies: lupus anticoagulant, anticardiolipin, or anti­ß2-glycoprotein I. Clinicians occasionally have difficulty making this diagnosis in patients with a clinical picture of APS but without any of the previously mentioned antiphospholipid antibodies. Such a status has been defined as "seronegative APS." Under these conditions, antiphosphatidylethanolamine antibodies deserve particular attention, as they have been described as being associated with the main clinical events of APS. Thus, this review focuses on issues related to the characteristics of antiphosphatidylethanolamine antibodies, including the nature of antigen targets and their role in homeostasis, the methodologic problems encountered in their detection, and their clinical associations.

ELISA for antiphosphatidylethanolamine antibody detection: high impact of assay buffer on results.

The aim of this study was to evaluate the influence on the results of the main variables of ELISA used for the detection of antiphosphatidylethanolamine antibodies (aPE). Forty sera from patients with either autoimmune disorders including antiphospholipid syndrome (APS) or the clinical features of APS only were assayed by ELISA performed under different conditions. Variables were sources of PE (egg yolk, soybean, bovine brain or Escherichiacoli), microtiter plates (plain or gamma irradiated) and buffer components-fetal calf serum (FCS), adult bovine plasma (ABP), adult bovine serum (ABS) or bovine serum albumin (BSA). aPE binding was decreased with PE from E. coli while the other tested PE gave comparable results. The influence of the type of plates was restricted to IgM isotype with slightly, but significantly higher optical densities with plain than with irradiated plates. Most importantly, the component buffer had the highest impact on the results as shown by a strong decrease of the signal by ABP or ABS. This inhibitory effect was confirmed by using mixtures of FCS or BSA with increasing concentrations of ABS. Partial delipidation of ABS resulted in a recovery of OD levels close to those obtained with FCS. This study is the first to demonstrate that aPE reactivity is dependent on the lipid concentration of the buffer component. These results highlight the need for standardization of aPE-ELISA for a better understanding of their clinical significance.

Low prevalence of anti-RNA polymerase III antibodies in a French scleroderma population: anti-RNA polymerase III scleroderma.

BACKGROUND: Anti-RNA polymerase III antibodies (anti-RNAP III) have been reported as potential immune markers of Systemic Sclerosis (SSc). Until now, their clinical use was disregarded because of technical difficulties to perform immunoprecipitation. Recently, ELISA kits became commercially available allowing an easy detection of anti-RNAP III. We intended to clarify the relevance of these antibodies in the diagnosis of SSc by ELISA detection. METHODS: The prevalence of anti-RNAP III was analyzed using two ELISA kits in 50 consecutive SSc patients from Marseilles in South of France. Controls included 66 patients with other systemic autoimmune diseases, 34 viral diseases and 50 healthy subjects. Positive results with at least one ELISA kit were controlled by immunoprecipitation which is the reference assay. RESULTS: In this study, positivity for anti-centromere and/or anti-topoisomerase I antibodies was observed in 84% of SSc patients. The prevalence of anti-RNAP III in SSc patients was 0% to 6% (3/50) depending on the ELISA kit and only 2% by immunoprecipitation. Concerning controls, two rheumatoid arthritis patients were positive using ELISA (6%), including one with immunoprecipitation confirmation. No anti-RNAP III was detected in systemic lupus erythematosus patients. Three blood donors and one viral disease control were positive using ELISA, but all were negative by immunoprecipitation. CONCLUSIONS: Anti-RNAP III was rarely detected in a French population of SSc patients. Their prevalence was even lower than the one observed in rheumatoid arthritis controls. Therefore local immunologic profiles should be established before deciding a change in clinical practice for SSc immune screening.

Prevalence of hepatitis C serum antibody in autoimmune diseases.

OBJECTIVE: To evaluate the prevalence of serum antibodies against hepatitis C virus and other infectious agents in a large cohort of well-characterized patients with autoimmune diseases (AID). METHODS: We utilized 1322 sera from patients with 18 different AID and 236 sera from healthy controls from the same countries and with similar age and sex distribution. All sera were tested for the presence of serum anti-hepatitis C virus (HCV) antibodies as well as antibodies directed at other infectious agents and autoantibodies. RESULTS: Anti-HCV antibody was detected in 115/1322 (8.7%) of patients with AID and 0.4% of matched healthy controls (P < 0.0001). The prevalence of anti-HCV antibody was significantly higher in 7/18 different AID (i.e. cryoglobulinemia, mixed cryoglobulinemia pemphigus vulgaris, vasculitis, secondary anti-phospholipid syndrome, Hashimoto's thyroiditis, and inflammatory bowel disease) compared to controls. Patients with AID and serum anti-HCV positivity had an increased prevalence of antibodies against hepatitis B virus, Toxoplasma gondii and Cytomegalovirus as opposed to a lower frequency of serum autoantibodies. CONCLUSIONS: The enhanced prevalence of anti-HCV serum antibodies in AID may suggest a role for HCV in tolerance to breakdown, similarly to its established role in mixed cryoglobulinemia. This immune mediated effect does not rule out the role of other infectious agents.

Clinical significance of antiphosphatidylethanolamine antibodies in the so-called "seronegative antiphospholipid syndrome".

The antiphospholipid syndrome (APS) is characterized by thrombosis and/or pregnancy morbidity associated with the presence of laboratory criteria such as antibodies directed towards cardiolipin or beta(2)-GPI and lupus anticoagulant. Recently, the term "seronegative APS " has been proposed to define patients with the typical clinical manifestations but with negative serologies. One explanation for such a context could be that some APS patients may only have antiphospholipid antibodies (aPL) other than the admitted laboratory criteria. This review is focused on antibodies directed against phosphatidylethanolamine (aPE) and underlines the interest of their investigation in the different clinical manifestations of APS.

BioPlex 2200 multiplexed system: simultaneous detection of anti-dsDNA and anti-chromatin antibodies in patients with systemic lupus erythematosus.

BACKGROUND: Antibodies for double-stranded DNA (anti-dsDNA) and chromatin represent specific markers of systemic lupus erythematosus (SLE). AIMS: (1) To evaluate the analytical performance of a multiplexed bead assay (BioPlex 2200) for the simultaneous detection of anti-dsDNA and anti-chromatin antibodies, (2) to compare the results for anti-dsDNA with those obtained using Farr assay, and (3) to analyze the clinical relevance of these antibodies when applied to the follow-up of SLE patients with active nephritis. PATIENTS AND METHODS: Hundred and five clinically characterized SLE patients and 96 healthy blood donors sera were analyzed by BioPlex 2200. RESULTS: Prevalence of these antibodies was significantly higher (p < 0.0001) in SLE patients than in controls (68 and 70% for anti-dsDNA and anti-chromatin, vs. 1% for both anti-dsDNA and anti-chromatin, respectively). If you consider a sample positive if either anti-dsDNA and/or anti-chromatin is positive, then the prevalence of these antibodies reached 78% (82/105) in SLE patients. For anti-dsDNA measurements, the kappa coefficient was 0.59 between BioPlex 2200 and Farr assay. Comparison between SLE patients with and without nephritis in a follow-up study showed that patients with active nephritis were associated with an increase of anti-dsDNA and anti-chromatin levels and a reduction of CH50, whereas no variation of antibody levels was observed in SLE patients without nephritis. CONCLUSION: Our results demonstrated a benefit of simultaneously measuring anti-dsDNA and anti-chromatin in SLE patients. The BioPlex 2200 achieved good analytical performances and proved to be a useful method for monitoring and diagnosing SLE.

Prevalence of autoantibodies to cyclic citrullinated peptide in patients with rheumatic diseases other than rheumatoid arthritis: a French multicenter study.

Our objective was to evaluate the prevalence of autoantibodies to cyclic citrullinated peptides (anti-CCP aAbs) in a cohort of patients with a variety of inflammatory or non-inflammatory rheumatic diseases other than rheumatoid arthritis (RA). Six hundred and nine serum samples were tested for anti-CCP aAbs and for rheumatoid factor (RF) using enzyme-linked immunosorbent assays and immunonephelometry. The prevalence of anti-CCP aAbs and RF reached 10% and 25%, respectively, using the positive cutoff value suggested by the manufacturers. Using a higher cutoff value (50 U/ml) for both aAbs, the prevalence was lower with 6% and 16%, respectively. The specificity of both markers for RA thus reached 94% and 84%, respectively. Anti-CCP aAbs were found to be elevated in inflammatory and also in non-inflammatory rheumatic diseases in the same proportion. Clinical data obtained for 36 positive patients showed that 17% developed RA within 5 years. In conclusion, anti-CCP aAbs are clearly more specific than RF for RA. Follow-up of anti-CCP aAbs-positive patients with inflammatory or non-inflammatory rheumatic diseases other than RA could be important considering the predictive value of these aAbs for the development of RA.

Evaluation of the BioPlex 2200 ANA screen for the detection of antinuclear antibodies and comparison with conventional methods.

BioPlex 2200 multiplexed assays system is an automatic method allowing detection of antinuclear antibodies (ANA). The aim of our study was to evaluate the determination of 13 autoantibodies against chromatinic and nonchromatinic nuclear antigens by the BioPlex 2200 system and to compare the results achieved by this method to those obtained with our routinely used immunoassays. One thousand and four serum samples consecutively sent for ANA detection were routinely tested by indirect immunofluorescence (IIF) on HEp2 cells. Among them, 321 were also analyzed by dsDNA enzyme immunoassay (EliA) test and 657 by double immunodiffusion (DID) for extractable nuclear antigen (ENA) antibodies. All the sera were evaluated by the BioPlex 2200 ANA screen kit allowing simultaneous detection of antibodies against the following antigens: dsDNA, chromatin, SSA-52 kDa, SSA-60 kDa, SSB, Sm, Sm/RNP, RNP-A, RNP-68 kDa, Scl70, centromere B, Jo-1, and P ribosomal proteins. The kappa coefficient between BioPlex 2200 and routine tests for detection of ANA on HEp2 cells, anti-dsDNA, and anti-ENA antibodies was, respectively, 0.31, 0.66, and 0.61. The comparison with our routine tests showed numerous discrepancies between IIF ANA screening and BioPlex but a good concordance for detection of anti-dsDNA and anti-ENA specificities. BioPlex 2200 system is a rapid and sensitive method for simultaneous quantitative detection of several autoantibodies. It is perfectly well adapted to determine ANA antigenic specificities of samples found positive using initial IIF screening. The capability of this multiplexed technology to analyze simultaneously 13 ANA autoantibodies leads to the rapid availability of an "autoimmune connective tissue disease serologic profile."

Clinical evaluation of a new quantitative enzyme-linked immunosorbent assay for detection of double-stranded DNA autoantibodies.

The measurement of autoantibodies specific for double-stranded DNA (anti-dsDNA) is a useful tool for the diagnosis and the prognosis of systemic lupus erythematosus (SLE). A new quantitative enzyme-linked immunosorbent assay (ELISA), ORG anti-dsDNA, is recently available for the determination of anti-dsDNA antibodies. The aim of this study was to evaluate the clinical performance of this new assay in a cohort of SLE patients. Seventy-five sera from SLE patients were tested by two methods for anti-dsDNA determination, ORG anti-dsDNA, and EliA anti-dsDNA. Normal controls were 60 sera from healthy subjects. Moreover, 37 sera from patients with non-SLE connective tissue diseases were tested in parallel. The levels of complement components (C3, C4, CH50) were measured by nephelometry. From SLE patients, 91% were positive against 9% in non-SLE patients and 2% in healthy subjects. The sensitivity, specificity, and Youden test for SLE were 90%, 98%, and 88%, respectively. The Yule test (1%) indicated a close association with the disease. The comparison with EliA anti-dsDNA showed a moderate concordance between the two tests in the group of SLE (kappa = 0.51) and a good concordance in the non-SLE group (kappa = 0.89). A significant inverse correlation was found with complement components levels, biological markers associated with disease activity. Our results show this new assay as sensitive and specific for the diagnosis of SLE. Moreover, the correlation with markers associated with disease activity makes it promising for clinical use.

Does the anti-prothrombin antibodies measurement provide additional information in patients with thrombosis?

The aim of this study is to get new insight into the relevance of IgG anti-prothrombin antibodies in patients with thrombosis and to determine whether human prothrombin alone (aPT) or complexed to phosphatidylserine (aPS/PT) should be preferentially used for measuring these antibodies by enzyme-linked immunosorbent assay (ELISA). To this end, prevalence of anti-prothrombin antibodies, their characteristics in terms of avidity and heterogeneity, and their relationship with anti-beta2 glycoprotein I antibodies (abeta2GPI) were studied in 152 patients with thrombosis. Patients were divided into two groups according to the presence or absence of antiphospholipid antibodies (aPL), called aPL+ or aPL-, respectively. In the aPL- group (n=90), the prevalence of anti-prothrombin antibodies was substantial (10%) but not significantly different from that of control (5%). In the aPL+ group (n=62), lupus anticoagulant (LA) or anticardiolipin antibodies (aCL) positive, 61% were positive for anti-prothrombin antibodies with no statistical difference between aPT and aPS/PT prevalence (42% vs. 55%, respectively). In the whole thrombotic population, 19% were only aPT and 34% only aPS/PT suggesting the presence of different antibodies. Absorption experiments confirmed the heterogeneity of aPT and aPS/PT. No difference in their avidity was demonstrated. From the aPL+ group, 60 were LA positive. Among them, 18% were negative for abeta2GPI and anti-prothrombin antibodies showing that the detection of these antibodies could not substitute for LA determination. In conclusion, our data show that the screening of the different anti-prothrombin antibodies is not warranted in the aPL+ group since these antibodies do not provide additional information compared to aCL, LA and/or abeta2GPI measurement. Nevertheless, the substantial prevalence of anti-prothrombin antibodies in the aPL- group should be further explored in a large prospective study.

Antiphosphatidylethanolamine antibodies are associated with an increased odds ratio for thrombosis. A multicenter study with the participation of the European Forum on antiphospholipid antibodies.

A multicenter study was set up to evaluate the prevalence, clinical and biological significance of antiphosphatidylethanolamine antibodies (aPE) in thrombotic patients with or without the main known clinical and biological risk factors for thrombosis. APE and antibodies, defined as the laboratory criteria of antiphospholipid syndrome (APS) -lupus anticoagulant, anticardiolipin and anti-beta(2)-GPI antibodies were measured in 270 patients with thrombosis (234 venous and 37 arterial) and 236 matched controls. APE were found in 15% of thrombotic patients compared to 3% of controls (p < 0.001) with no predominant isotype, no association with the main known clinical or biological risk factors for thrombosis neither with a type of thrombosis, arterial or venous. In a multivariate logistic regression analysis of antibodies, aPE showed the highest association with thrombosis (odds ratio [OR]: 4.2, p < 0.001). Moreover, using a multivariate analysis in a case-control subgroup study on 158 patients, IgGaPE were found to be significantly associated with venous thrombosis (OR:6;p = 0.005). Interestingly, 25 of the 40 aPE-positive patients (63%) were negative for the APS laboratory criteria. Most of them (21/25) had venous thrombosis, recurrent in ten of them. Four patients also suffered from early or late miscarriages. Our results underline the strength of the association between the presence of aPE and thrombosis and suggest their measurement in thrombotic patients, especially when lupus anticoagulant, anticardiolipin or anti-beta(2)-GPI antibodies are absent.

Variability of anti-beta2 glycoprotein I antibodies measurement by commercial assays.

The aim of this study was to evaluate the agreement in assay results between commercial kits for the measurement of anti-beta2glycoprotein I antibodies. Ten manufacturers provided one IgG and one IgM kit to three testing centres. Samples from patients with primary (n = 13) or secondary (n = 3) antiphospholipid syndrome (APS), from lupus patients without APS features (n = 6) and from normal individuals (n = 2) were tested in the three centres according to manufacturers' instructions. Dilutions in normal serum of a pool made from positive patients' samples (Forum Calibrators) and dilutions of humanized monoclonal antibodies (MoAbs) were used as additional calibrators. The calibration curves obtained with each calibrator differed widely between kits. The rate of positivity of patients' samples varied from 7 to 16 for IgG and from 2 to 17 for IgM, depending on the kit. Perfect agreement occurred in 12/22 samples for IgG and 5/22 samples for IgM. Samples from normals were found negative by all kits. Between kits, cutoff values varied up to five fold when expressed in Forum Calibrators arbitrary units and up to three fold when expressed in MoAbs equivalents. Examination of discrepant samples indicated that about half of the discrepancies, scoring 8:2 and 9:1, involved the same few kits. In highly discrepant samples, some kits appeared as high responders as compared to others. In conclusion, with the exception of a few kits, agreement in assay results was acceptable. In conclusion, additional efforts are however necessary, especially concerning the way to assess the cutoff point and the adoption of a reference calibrator, in order to improve standardization of the assays.

Heterogeneity of anti-beta2-glycoprotein I antibodies. A factor of variability in test results.

The aim of this study was to evaluate the heterogeneity of IgGanti-beta2-glycoprotein I antibodies (IgG-abeta2GPI) as regarding their reactivity pattern against different sources of human beta2 GPI, their avidity and their association with clinical events of antiphospholipid syndrome (APS). Three thousand six hundred and eighty-four consecutive patient sera were routinely tested for IgGabeta2 GPI over 1 year using an in-house ELISA with 2 different commercial preparations of human purified beta2GPI. Of the 340 sera found positive, all those clinically documented were included in this study; 61 were positive with only one preparation (S1) and 59 with both (S2). The results of ELISA were confirmed by Western blot. Heterogeneity was stressed by testing sera with a human recombinant protein and 3 beta2GPI-related peptides. No contribution of glycosylation in the binding to beta2GPI was found. The avidity indices for each protein were significantly higher in S1 than in S2 (p=0.0021). S2 were more associated with antiphospholipid antibodies than S1 (75% versus 21% ; p<0.0001). A similar frequency of the main clinical features of APS was found in S1 and S2 sera (69% and 71%, respectively). In conclusion, our data show a heterogeneity in the antigenic reactivity pattern of IgG- abeta2 GPI and a relationship between a binding profile and antibody avidity. This heterogeneity could represent a crucial factor of variability in test results and underlines the difficulty of getting standardisation.

Minimal requirements for antiphospholipid antibodies ELISAs proposed by the European Forum on antiphospholipid antibodies.

Antiphospholipid ELISAs are part of the Antiphospholipid Antibodies Syndrome classification criteria, having the same diagnostic value as lupus anticoagulant. However, sometimes their results appear scarcely meaningful especially when wide metanalyses studies are performed, probably because of their well-known inter-laboratory variability. The application of a common protocol was shown to improve the test reproducibility, but this observation did not have any influence on the routine performances. After discussion among experts at the European level, we identified four conditions named "minimal requirements" considered useful to decrease the inter-laboratory variability: (1) to run the samples in duplicate; (2) to determine the cut off level in each laboratory analysing at least 50 samples from normal subjects, possibly age- and sex-matched with the patient population usually attending the Centre; (3) to calculate the cut-off level in percentiles; (4) to use stable external control in the tests. A collaborative study involving 36 European centres proved that the use of monoclonal anti-beta2 glycoprotein I antibodies, HCAL (IgG) and EY2C9 (IgM) as standards, can help to reduce the inter-laboratory coefficient of variation both in anticardiolipin (aCL) and anti-beta2GPI (anti-beta2 glycoprotein I) ELISA. Therefore, we propose HCAL and EY2C9 as external controls, but other monoclonal or polyclonal preparations may be considered. During an interactive workshop held last May in Italy, 16 companies producing these tests agreed to consider the introduction of the "requirements" in their products. We suggest to adopt these "requirements" particularly in clinical studies, in order to compare more easily the literature data.

Combined search for anti-beta2-glycoprotein I and anticardiolipin antibodies in antiphospholipid syndrome: contribution to diagnosis.

In this study we sought to assess (1) the diagnostic value of a combined search for anti-beta(2)-glycoprotein (abeta(2)-GPIs) and anticardiolipin antibodies (aCLs) in primary (APS I) and secondary (APS II) antiphospholipid syndrome and (2) the influence of the beta(2)-GPI preparation in the ELISA's results. abeta(2)-GPI and aCL concentrations were assessed in 70 patients with APS and compared with those in 65 patients with systemic lupus erythematosus (SLE) without clinical features of APS. In APS patients (38 with APS I, 32 with APS II), the diagnosis had to have been made at least 3 years earlier; in subjects with SLE, the diagnosis had to have been made at least 5 years earlier. All serum samples were tested for abeta(2) -GPI with the use of an in-house ELISA with an abeta(2) -GPI preparation from human plasma. Samples negative for abeta(2) -GPI were controlled with 2 additional beta(2)-GPI preparations, 1 from human serum and 1 from bovine serum. In APS, abeta(2)-GPIs were more frequent than in SLE (76% and 15%, respectively; P <.0001), mainly with IgG isotype and with significantly higher levels than those found in SLE. The specificity for APS was 92% for IgG abeta(2)-GPIs and 68% for IgG aCLs. The highest association with APS was found for the combination of the 2 markers (odds ratio 29; 95% confidence interval 10-76; P <.0001). Among the APS patients, 6 were positive for aCL only and remained negative regardless of which beta 2 -GPI preparation was used; 1 patient was aCL-negative and only positive with human beta 2 -GPI. These data emphasize the heterogeneity of the APS immunologic profile and the diagnostic possibilities of both antibodies.

Features associated with epilepsy in the antiphospholipid syndrome.

OBJECTIVE: To assess the frequency of epilepsy in primary and secondary antiphospholipid syndrome (APS); to analyze the clinical and laboratory features characterizing those with epilepsy in a cohort of 538 patients with APS; and to find associated features that would suggest risk factors for epilepsy in APS. METHODS: We analyzed the clinical features of patients with APS who had epilepsy and compared them to the clinical features of non-epileptic APS patients. RESULTS: Of 538 APS patients, 46 (8.6%) had epilepsy. Epilepsy was more prevalent among APS secondary to systemic lupus erythematosus (SLE) compared to primary APS (13.7% vs 6%; p < 0.05). The patients with epilepsy had a higher prevalence of central nervous system (CNS) manifestations including focal ischemic events (strokes or transient ischemic events, 54.3% vs 24.6%; p < 0.0001) and amaurosis fugax (15.2% vs 4.9%; p < 0.05). APS patients with epilepsy had a higher frequency of valvular pathology (30.4% vs 14.6%; p < 0.01), thrombocytopenia (43.5% vs 25%; p < 0.05), and livedo reticularis (26.1% vs 11.5%; p < 0.01). The multivariate logistic regression analysis found CNS thromboembolic events as the most significant factor associated with epilepsy, with an odds ratio (OR) of 4.05 (95% confidence interval, CI: 2.05-8), followed by SLE (OR 1.4, 95% CI 1.2-4.7), and valvular vegetations (OR 2.87, 95% CI 1-8.27). CONCLUSION: Epilepsy is common in APS and most of the risk seems to be linked to vascular disease as manifested by extensive CNS involvement, valvulopathy, and livedo reticularis and to the presence of SLE. These factors, however, explain only part of the increased occurrence of epilepsy in APS and other causes such as direct immune interaction in the brain should be investigated.

Endothelial microparticles: a potential contribution to the thrombotic complications of the antiphospholipid syndrome.

The antiphospholipid syndrome (APS) refers to persistent anti-phospholipid antibodies (aPL) associated with thrombotic and/or obstetrical complications. The endothelial cell is a target of aPL which can induce a procoagulant and proinflammatory endothelial phenotype, as reported both in vivo and in vitro. Microparticle production is a hallmark of cell activation. In the present study, the presence of endothelial microparticles (EMP) in the plasma of APS patients was investigated. To determine if there is a correlation with certain biological and clinical features, EMP levels were measured in thrombosis-free patients with systemic lupus erythematosus (SLE) patients, with and without aPL, in patients with non aPL-related thrombosis, as well as in healthy controls. Compared to healthy subjects, elevated plasma levels of EMP were found in patients with APS and in SLE patients with aPL, but not in SLE patients without aPL or in non aPL-related thrombosis. EMP levels were also associated with Lupus Anticoagulant (LA) detected by a positive Dilute Russell's Viper Venom time (DRVVT). In parallel, we analyzed the capacity of these plasma to induce vesiculation of cultured endothelial cells. We demonstrated an increase of EMP generated in response to plasma from patients with auto-immune diseases. Interestingly, only APS plasma induced the release of EMP with procoagulant activity. These ex vivo and in vitro observations indicate that generation of EMP in APS and SLE patients results from an autoimmune process involving aPL. Production of procoagulant microparticles in APS patients may represent a new pathogenic mechanism for the thrombotic complications of this disease.