Antiphospholipid syndrome and stroke]

Antiphospholipid syndrome is characterized by arterial or venous thrombosis, and the presence of antiphospholipid antibodies (aPL). APL are considered to be a cause of an acquired hypercoagulable state leading to stroke and transient ischemic attack (TIA). We examined the causes in 50 young patients with ischemic stroke. The most prevalent cause was atherosclerosis and the incidence of APS was 12.5%. APL comprise a heterogeneous group of autoantibodies, such as beta2-glycoprotein I dependent anticardiolipin antibody (beta2-GPIaCL), lupus anticoagulant (LA), and other antiphospholid-protein antibodies. We examined the incidence and the pathogenic role of antiphospholipid protein antibodies. The subjects comprised 250 patients (155 male, 95 females) with ischemic stroke, aged 26 to 92 years (mean 72 years). We measured beta2-GPI aCL, IgG aCL, LA, phosphatidyserine dependent antiprothrtombin antibody (PS-PT), antiphosphatidyl-serine antibody (PS), antiphosphatidyl-inositol antibody (PI) in each patient. The incidence of beta2-GPI aCL, IgG aCL, LA, phosphatidyserine, PS-PT, PS, and PI was 2.8%, 12%, 9.2%, 7.2%, 9.6%, and 8.8%, respectively. The incidence of young stroke patients under 50 years was 5.2%. Among 13 young stroke patients, 5 had SLE. Among 23 patients with LA., 18 (78%) patients had PS-PT. Anti-PS-PT antibody is closely related to LA. Antinuclear antibody was detected in 79% of the patients with aPS and/or aPI. We compared the carotid ultrasonographic findings in positive aPI or aPS patients with those in negative ones. Increased IMT, plaque score and carotid stenosis were more common in aPI and aPS-positive patients than in negative ones Three of 5 patients who showed positive beta2-GPI, aCL and LA, simulataneously, had sysyemic lupus erythematosus as an immulological background. Two of 3 patients with PI and/or PS and beta2-GPI and/or LA were patients with SLE. Antiphospholipid antibody was considered to be a risk factor of stroke, especially in SLE and/or young female patients. The incidence of lupus anticoagulant is more common than beta2-GPI aCL in ischemic stroke. In SLE patients with stroke, multi-antiphospholipid-protein antibodies was inclined to be present. LA is closely related to ant-PS-PT and aPI and aPS are associated with anti-nuclear antibody and precipitation of atherosclerosis.     

Platelet activation induced by combined effects of anticardiolipin and lupus anticoagulant IgG antibodies in patients with systemic lupus erythematosus--possible association with thrombotic and thrombocytopenic complications

Antiphospholipid antibodies (aPL) are well known to be associated with arterial and venous thrombosis. In a series of 180 patients with systemic lupus erythematosus (SLE), the prevalence of arterial thrombosis was obviously higher in the patients who had both anticardiolipin antibodies (aCL) and lupus anticoagulant (LA) (17/35, 48.6%, p<0.05) (Table 1) than in the other patients bearing aCL or LA alone or neither of them (2/145, 1.4%). Since a substantial fraction of the former group of patients with arterial thrombosis also had thrombocytopenia (12/17, 70.6%), there was a possibility that aCL and LA might have enhanced platelet activation and aggregation. To test this possibility, we studied the in vitro effects of aCL and LA on the enhancement of platelet activation by flow cytometric analysis using anti-CD62P and anti-CD41 monoclonal antibodies directed against platelet activation-dependent granule-external membrane (PADGEM) protein and platelet glycoprotein IIb (GPIIb), respectively. Platelet activation defined by the surface expression of CD62P was not induced by aCL+ x LA+ plasma only, but was significantly augmented by aCL+ x LA+ plasma in combination with adenosine diphosphate (ADP) at a low concentration that had only a modest effect on platelet activation. In contrast, aCL+ x LA-, aCL- x LA+ and aCL- x LA- plasma samples were incapable of enhancing platelet activation in the presence or absence of ADP stimulation. In addition to plasma samples, the purified IgG from aCL+ x LA+ plasma (aCL+ x LA+-IgG) also yielded apparent enhancement of platelet activation induced by ADP. Furthermore, platelet activation was generated by the mixture of aCL+ x LA--IgG and aCL- x LA+-IgG fractions prepared from individual patients, but not by each fraction alone. These results suggest that aCL and LA may cooperate to promote platelet activation, and may be involved, at least partially, in the pathogenesis of arterial thrombosis and thrombocytopenia in patients with SLE.     

抗心磷脂抗体在狼疮肾炎患者中的临床意义*★

背景：以往的研究表明，在系统性红斑狼疮及抗磷脂抗体综合征患者中，升高的抗心磷脂抗体滴度与血管血栓形成、血小板减少及反复流产的发生明显相关。但有关抗心磷脂在狼疮性肾炎患者中的临床意义的研究报道却不完全统一。 目的：探讨抗心磷脂抗体在中国狼疮性肾炎患者中的阳性率及临床意义。 设计：前瞻性单一样本的随访观察。 单位：深圳市第四人民医院香蜜湖风湿病分院，广东医学院深圳风湿病研究所。 对象：选择2001-03/2003-10于深圳市第四医院香蜜湖风湿病分院风湿科门诊就诊或住院的狼疮性肾炎患者97例。均符合美国风湿病学学会（ACR）1997年修订的狼疮性肾炎的诊断和分类标准。纳入对象均对检测项目知情同意。 方法：记录患者入院后的临床资料和辅助检查结果。应用酶联免疫吸收法检测患者血清中的抗心磷脂抗体，阳性判断标准为测定值超过100 U/mL。大剂量口服强的松联合环磷酰胺静脉冲击治疗以诱导缓解，然后逐渐将强的松减量，将环磷酰胺换成硫唑嘌呤以维持疗效。同时使用其它药物控制可能合并的高血压、高血脂与关节痛等症状。每半年对纳入对象进行定期随访，记录狼疮性肾炎患者的临床资料及实验室检查结果，共3年。 主要观察指标：患者的性别、年龄、系统性红斑狼疮病情活动指数、血栓形成、病理妊娠等临床表现及肾功能等实验室检查结果。 结果：实验共纳入狼疮性肾炎患者97例，83例进入结果分析，14例脱落。在入选的97例患者中，其发病后被确诊时抗心磷脂抗体阳性者有38例（39%），高血压，血小板减少及雷诺现象在伴有抗心磷脂抗体阳性的狼疮性肾炎患者中更为常见。IgG型抗心磷脂抗体阳性狼疮性肾炎患者更易发生血管血栓形成；抗心磷脂抗体阳性狼疮性肾炎患者更易发生流产、早产和死胎以及慢性肾功能不全恶化。 结论：抗心磷脂抗体在狼疮性肾炎患者中的阳性率为39%，抗心磷脂抗体阳性的患者更易出现高血压，血小板减少及雷诺现象，抗心磷脂抗体阳性对预测狼疮性肾炎出现血管血栓形成、病理妊娠及慢性肾功能不全恶化可能有一定作用。     

Detection of complement-fixing antiphospholipid antibodies in association with thrombosis

Antiphospholipid antibody (aPL) is a hallmark of antiphospholipid syndrome (APS), characterized by thrombosis and recurrent fetal loss. We developed a novel ELISA system to detect complement-fixing ability of anticardiolipin antibody (aCL), and evaluated its clinical usefulness through studying the prevalence of the antibodies in rheumatic diseases, especially in association with thrombosis and recurrent abortion. Among 189 patients with rheumatic diseases, the complement-fixing aCL was positive in 26 (83.9%) of 31 patients with APS and 2 (1.3%) of 158 with other disease categories, whereas it was not positive among 52 normal subjects. Twenty-seven of 28 patients (96.4%), who were positive for complement-fixing aCL, had the episodes or history of thrombosis and/or recurrent abortion, at the time we studied. The remaining one in this group developed APS manifesting pulmonary infarction and occlusion of mesenteric artery 6 months after the evaluation. The sensitivity and specificity of this assay system were 75.0% and 99.3%, respectively, in relation with thrombotic episodes. On the other hand, the IgG aCL were positive in 28 (77.8%) of 36 cases with recent thrombotic episodes and 24 (15.7%) of 153 cases with no recent thrombotic episodes. The sensitivity and specificity of IgG aCL assay system were 77.8% and 84.3%, respectively, in relation with thrombotic episodes. These results indicate that complement-fixing aCL may specifically occur in association with the episodes of thrombosis and/or recurrent abortion in patients with APS compared to IgG-aCL. The method for detecting the complement-fixing aCL is simple, and it provides the useful diagnostic marker for thrombotic manifestations associated with APS.     

Morbidity of lupus anticoagulants in children: a single institution experience

INTRODUCTION: The lupus anticoagulant (LA) and the anticardiolipin antibodies (ACA) are the antiphospholipid antibodies more relevant clinically. Their clinical manifestations are diverse with most patients being asymptomatic while others present venous or arterial thrombosis, and more rarely, bleeding. Our objectives were to evaluate clinical presentation of LA in children and to correlate it to LA behavior. PATIENTS AND METHODS: A retrospective cohort of patients (under 18 years old) who had a positive determination of LA followed by at least another determination of LA at a variable period was evaluated. Personal and family history, including infectious diseases temporally related to the event, were recorded. The screening of other coagulation disorders was performed according to symptoms, family history or laboratory results. RESULTS: Thirty-six patients were evaluated, median age was 10.8 years old, and 52.8% were female. Asymptomatic patients were 19.4% (7/36) of study population. Bleeding and thrombosis were found in 52.8% and 27.8%, respectively. Median LA determinations per patient were 3. von Willebrand disease was diagnosed in 66.7% of patients consulting for bleeding. A concomitant hemostatic defect was found in 8/10 patients with thrombosis (p = 0.003). LA behavior was not uniform and not correlated to symptoms. CONCLUSIONS: Most LA found in children is incidental and asymptomatic. In children with bleeding, LA might be a fortuitous finding associated with VWD. The persistence of LA does not imply a higher risk of thrombosis.     

Does the anti-beta2-glycoprotein I antibody provide additional information in patients with thrombosis?

OBJECTIVE: To investigate whether the anti-beta(2)-glycoprotein I (anti-beta(2)GPI) antibody may provide additional information in patients with thrombosis in conjunction with the lupus anticoagulant (LAC) or anticardiolipin (aCL) antibody. METHODS: We selected 235 patients whose plasma were tested for the presence of all three antiphospholipid (aPL) antibodies (LAC, aCL, and anti-beta(2)GPI) and were positive for at least one aPL antibody from January 2000 to December 2001. The LAC test was performed using dilute activated thromboplastin time reagent (dAPTT) and dilute Russell viper venom time reagent (dRVVT). ACL (IgG/IgM) and anti-beta(2)GPI (IgG/IgM) were detected by enzyme-linked immunosorbent assay (ELISA). Clinical data were collected and analysed in all patients with aPL antibody. RESULTS: Of the 235 patients with aPL, thrombosis was detected in 76 patients (28.0%). Of the 76 patients with thrombosis, 29 were positive for LAC, 9 for aCL, 7 for anti-beta(2)GPI, 3 for LAC+aCL, 9 for aCL+anti-beta(2)GPI, 11 for LAC+anti-beta(2)GPI, and 8 for LAC+aCL+anti-beta(2)GPI. The rate of thrombosis was significantly different (p=0.01) among single positive patients (45/163, 27.6%), double positive patients (23/60, 38.3%), and triple positive patients (8/12, 66.7%). In single positive patients, the rate of thrombosis was highest in LAC positive patients (29/85, 34.1%). In double positive patients, the LAC+anti-beta(2)GPI positive group (11/24, 45.8%) and aCL+anti-beta(2)GPI positive group (9/22, 40.9%) had higher rates of thrombosis than the LAC+aCL positive group (3/14, 21.4%). CONCLUSION: Single positivity for anti-beta(2)GPI explained 9.2% of thrombotic events in the absence of LAC or aCL. Double or triple positivity for aPLs were associated with a higher rate of thrombosis than single positivity for aPL. Our results suggest that anti-beta(2)GPI provides additional information in patients with thrombosis in conjunction with LAC or aCL.     

Lupus anticoagulant testing in Europe: an analysis of results from the first European Concerted Action on Thrombophilia (ECAT) survey using plasmas spiked with monoclonal antibodies against human beta2-glycoprotein I.

Lupus anticoagulants (LA) are immunoglobulins directed to either prothrombin or Beta-2-glycoprotein 1(beta1GPI) bound to phospholipids. Most patients with LA have both beta2GPI- and prothrombin-dependent antibodies. Several recent reports have shown that LA is more strongly associated with thrombosis than anticardiolipin antibodies (aCL). Therefore, an accurate detection of LA is of utmost importance in patients suspected of an antiphospholipid syndrome. We recently raised a series of murine monoclonal antibodies against human Beta-2-glycoprotein I (beta2GPI) with LA activity similar to affinity purified human beta2GPI-dependent LAs. A normal plasma pool, and the same pool spiked with LA positive anti-beta2GPI antibodies at two potency levels, were used as materials in an external quality assessment scheme organised by the European Concerted Action on Thrombosis (ECAT). Fifty nine laboratories participating in this trial were asked to test for the presence of a LA in the 3 samples submitted. The majority (82%) of the participants found the high potency LA sample to be positive. Only 37% of the laboratories considered the weak potency LA sample to be positive. The submission of a normal sample, a weakly positive sample and a clearly positive sample enabled us to compare the relative LA responsiveness of the different screening assays used. Clotting time ratios varied from 0.81 to 3.28 for sample B and from 0.66 to 5.32 for sample D. In general, the highest clotting time ratios were found with the dilute prothrombin time (dPT), the dilute Russell Viper Venom time (dRVVT) and the Kaolin Clotting time. The most frequently used screening tests were the aPTT and the dRVVT. With the various assay systems, LA responsiveness varied largely according to the reagents used. For the beta2GPI-dependent LA used in this study, PTT LA clearly showed the highest responsiveness among the aPTT reagents and Innovin among the dPT reagents. The present study also shows that many laboratories still rely on poorly responsive screening assays for their LA tests. Other laboratories rely on sensitive and more specific integrated test systems based on a sensitive screening assay with a low phospholipid content and a confirmatory test employing high phospholipid concentrations. The most used integrated system was dRVVT based. However, also here the LA responsiveness was largely reagent dependent. In conclusion, many laboratories still rely on poorly responsive screening assays by which weakly positive LA samples are misdiagnosed. LA positive anti-beta2GPI moabs have a potential for the unlimited production of LA control specimens, that may help hemostasis laboratories choose more LA responsive assay systems and to assess intralaboratory precision of their LA testing.     

Antiphospholipid antibodies and cerebral ischemia in young people

The importance of a prothrombotic state as a cause of ischemic stroke in young adults is ill defined. We examined 46 unselected patients under age 50 years with cerebral ischemia for anticardiolipin antibody (aCL) and lupus anticoagulants (LA), over a 3-year-period. Age- and sex-matched patients with other neurologic diseases served as a noncerebral ischemia comparison group to test whether (1) stroke/transient ischemic attacks (TIA) in young people is associated with aCL and/or LA, and (2) their presence is specific to cerebral ischemia. In the stroke/TIA group, 21 patients had aCL or LA and 25 had neither, whereas in the control group, 2 patients had aCL and 24 had neither. Equal numbers of stroke/TIA patients with and without antiphospholipid antibodies (aPL) had other stroke risk factors. Patients with aPL and cerebral ischemia, however, had a more frequent history of multiple events than those without them. These antibodies occur with undue frequency in young patients with stroke/TIA and are not associated with a concurrent diagnosis of systemic lupus in most cases. A coexistent aPL-associated prothrombotic state may be a key determinant of whether patients with atherosclerosis, mitral valve prolapse, or other structural lesions experience recurrent ischemia.     

Anticardiolipin antibodies: a study in cerebral venous thrombosis

OBJECTIVES: Anticardiolipin antibodies (aCL) have been recognized as a marker for an increased risk of thrombosis. There are no documented reports from India on the prevalence of aCL in patients with cerebral venous thrombosis (CVT). Our study aimed at establishing the prevalence of these antibodies in patients with CVT and evaluating their clinical significance. SUBJECTS AND METHODS: Thirty-one patients with CVT diagnosed by angiography and/or cranial CT were investigated for the presence of aCL along with 31 age- and sex-matched normal controls. All subjects had no overt evidence of systemic lupus erythematosis or related autoimmune disorders. The titres of IgG and IgM type of aCL were estimated in the sera using a solid phase enzyme-linked immunosorbent assay. RESULTS: Anticardiolipin antibodies were detected in 22.6% of CVT patients compared to 3.2% of normal controls (95% confidence interval (CI) 1.01 to 75.65). Five CVT patients had both IgG and IgM antibodies, and 2 had only IgG antibodies. The aCL positive group did not differ from the aCL-negative group with respect to the clinical characteristics and the demographic and risk factor profile. CONCLUSION: The findings suggest that anticardiolipin antibodies are a risk marker for cerebral venous thrombosis. Further studies on a larger group of patients are needed to establish the role of aCL in the pathogenesis of CVT.     

The dilution effect of equal volume mixing studies compromises confirmation of inhibition by lupus anticoagulants even when mixture specific reference ranges are applied

INTRODUCTION: One of the recommended criteria for the laboratory diagnosis of lupus anticoagulants (LA) is demonstration of inhibitory activity. This is confirmed by performing mixing tests with normal plasma, usually in a 1:1 ratio, and demonstrating persistence of an abnormal clotting time in the screening test with significant confirmatory test reduction. However, the mixing with normal plasma can dilute the antibodies to undetectable levels and generate apparent negative results. No guidelines or consensus exist in how to interpret mixing study results. PATIENTS AND METHODS: The present study assessed the 1:1 mixing study results from 600 patients with a thrombotic history positive for LA demonstrated in neat plasma by individual assays, or combinations, of dilute Russell's viper venom time, dilute activated partial thromboplastin time, activated seven lupus anticoagulant assay and Taipan snake venom time, plus confirmatory tests. Mixing tests were assessed initially using locally derived neat plasma reference ranges and subsequently with mixture specific ranges. RESULTS: The mixture specific ranges had lower upper limits. Of the total LA positive results, 32.5% were positive in the mixing studies when neat plasma reference ranges were applied, and a further 11.2% demonstrated LA activity when using the mixture specific ranges. The remaining 56.3% had been diluted such that they did not elevate the screening test above the upper limit of normal or generated minimal prolongation with an insignificant difference between the screen and confirmatory test result sufficient to confirm LA activity. CONCLUSIONS: The significant impact of the dilution effect in 1:1 mixing studies emphasises the limitations of mixing studies as a vehicle for confirmation of inhibition by LA antibodies.     

Antiphospholipid syndrome: diagnostic aspects of lupus anticoagulants

Antiphospholipid syndrome (APS) is an autoimmune disorder in which antiphospholipid antibodies (aPL) are thought to be involved in the development of venous and/or arterial thrombosis. APL found in this syndrome are antibodies directed against a variety of phospholipid (PL) binding-proteins of which beta3-glycoprotein I (beta2GPI) and prothrombin are considered to be the major antigens. Some of these antibodies prolong PL-dependent clotting reactions and are termed lupus anticoagulants (LA). Autoimmune aPL which bind through beta2GPI to cardiolipin are called anticardiolipin antibodies (aCL). Clinical studies indicate that LA is a stronger risk factor for thrombosis than aCL. The production of monoclonal antibodies against beta2GPI and prothrombin has enabled us to understand the mechanism by which LA prolong coagulation in vitro. LA form bivalent antigen-antibody complexes with increased affinity for PL which compete with coagulation factors for the same catalytic surface. These LA positive monoclonal antibodies may be helpful in further improving the laboratory diagnosis of LA.     

Anti-beta2-glycoprotein I antibodies are associated with pregnancy loss in women with the lupus anticoagulant

The presence of lupus anticoagulant (LA) predisposes to fetal loss and to venous and arterial thrombosis; however, a subgroup of women is unaffected by pregnancy loss. Currently, no predictive markers are available for the identification of women positive for LA at increased risk for pregnancy loss. It was the aim of our study to investigate whether increased anti-beta2-GPI-antibodies predict pregnancy loss in women positive for LA. We performed a cross-sectional study in a cohort of 39 women with persistent LA, who had in total 111 pregnancies. Fifteen women had exclusively normal pregnancies (30 pregnancies) and 24 women had pregnancy losses (81 pregnancies). Anti-beta2-GPI-antibodies were determined using a semiquantitative enzyme linked immunoassay (QUANTA Lite beta2 GPI IgG and IgM; Inova Diagnostics). Increased levels of anti-beta2-GPI antibodies were significantly associated with pregnancy loss [odds ratio (OR) 9.6, 95% confidence interval (CI) 1.6-56.4]. This risk was even higher in the subgroup of women (n = 16) with more than two miscarriages or fetal loss after the first trimester [OR 13.1, 95% CI 1.4-126.3]. There was no significant association between anticardiolipin antibodies and pregnancy loss [OR 3.5, 95% CI 0.7-17.6]. The co-existence of anti-beta2-GPI and anticardiolipin antibodies was also predictive for pregnancy loss [OR 6.1, 95% CI 1.3-29.7]. Interestingly, the prevalence of thrombosis was similar between women with normal pregnancy (87%) and those with pregnancy loss (75%). We conclude that increased levels of anti-beta2-GPI antibodies are predictive for pregnancy loss among women positive for LA, and that prophylactic treatment should be considered in these women even without a history of previous pregnancy loss.     

Thromboembolic risk in patients with high titre anticardiolipin and multiple antiphospholipid antibodies

Asymptomatic antiphospholipid antibody (aPL) carriers with high risk for thrombosis may benefit from preventive anticoagulation. It was our objective to test whether the risk of thrombosis increases with: 1). increasing titres of anticardiolipin antibodies (aCL) after adjustment for other cardiovascular risk factors and 2). the number of aPL detected. In a cross-sectional study, blood was collected from clinics in two teaching hospitals. The study included 208 individuals suspected of having an aPL and 208 age- and sex-matched controls having blood drawn for a complete blood count. Clinical variables included history of previous arterial (ATE) or venous (VTE) thrombotic events, traditional risk factors for cardiovascular disease, and systemic lupus erythematosus (SLE). Laboratory variables included IgG/IgM aCL, lupus anticoagulant, and IgG/IgM anti-beta2-glycoprotein I. Mean age was 46.5 years and 83% were female. Seventy-five of the 416 participants had >or= 1 aPL, and 69 had confirmed >or= 1 ATE or VTE. Family history was positive in 48% of participants, smoking in 28%, hypertension in 16%, diabetes in 6%, and SLE in 20%. A 10-unit increase in aCL IgG titre was associated with an odds ratio (OR) [95% CI] of 1.07 [1.01-1.13] for ATE and 1.06 [1.02-1.11] for VTE. The odds of a previous thrombosis increased with each additional aPL detected: 1.5 [0.93-2.3] for ATE and 1.7 [1.1-2.5] for VTE. These results indicate that increased titres of aCL and multiple aPL were associated with an increased risk of a previous thrombotic event.     

Neurological disease associated with anticardiolipin antibodies in patients without systemic lupus erythematosus: clinical and immunological features

Summary Anticardiolipin antibodies (aCL), one of a group of antiphospholipid antibodies which include the lupus anticoagulant (LA), may occur in association with systemic lupus erythematosus (SLE) and are less commonly detected in other diseases. We retrospectively reviewed the clinical and immunological features of 39 consecutive patients with abnormal aCL identified by one laboratory, to examine the spectrum of neurological disease in those patients without SLE. Fourteen patients in this category are described, 6 of whom did not have evidence of LA. All but 1 presented with neurological symptoms. Stroke and migraine dominated the clinical presentation, but many patients had features to suggest the presence of a hypercoagulable state. This study lends support to the concept of a primary antiphospholipid syndrome.     

Antiphospholipid antibodies and hyperhomocysteinaemia in patients with vascular occlusive disease

Hyperhomocysteinemia (HHcy), lupus anticoagulant (LA) and anticardiolipin antibodies (ACA) are independent risk factors for thrombosis. Even though risks are cumulative, the clinical impact of the association is unknown. Preliminary data suggested that HHcy might be associated with transient LA and ACA, disappearing after lowering HHcy. We prospectively evaluated the association of HHcy and LA/ACA, the effect of lowering HHcy with folic acid in LA behavior, and the correlation of the initial dRVVT with LA behavior after folic acid in 210 patients with thrombosis and adverse pregnancy outcomes. Prevalence of HHcy among patients with LA/ACA was 40%. Thirty-one patients exhibited only HHcy (15%; Group 1), 106 (50%; Group 2) had only LA/ACA, while 73 (35%; Group 3) had both. After therapy, 63% and 64% of LA/ACA remained positive in Group 3 and 2, respectively. We observed a trend towards a more positive dRVVT in persistent LA after lowering HHcy. No differences in clinical presentation or in outcomes after two years of followup were observed among the groups. Even though the association of HHcy and LA/ACA is common in patients with thrombosis, it might have no prognostic implications if Hcy levels are lowered. Currently, no laboratory findings correlate with LA behavior, which is independent of homocysteine levels and vitamin treatment.     

The lupus anticoagulant is a risk factor for myocardial infarction (but not atherosclerosis): Hopkins Lupus Cohort

Antiphospholipid antibodies, both anticardiolipin and lupus anticoagulant, are common in SLE. We asked, in a prospective cohort, whether these antibodies are predictive of atherosclerosis and/or coronary artery disease. Methods: Three hundred eighty patients, 92% female, 49% Caucasian, 51% African-American, mean age 46.4±12.3 years are followed quarterly, with assessment of both anticardiolipin and lupus anticoagulant (dRVVT). These patients underwent both helical CT and carotid duplex. Results: Both the lupus anticoagulant and anticardiolipin are predictive of later venous or arterial thrombosis. Twenty years after diagnosis, SLE patients with the lupus anticoagulant (LA) have a 50% chance of a venous thrombotic event. Myocardial infarction occurs significantly more often in those with LA 22% vs. 9%, p=0.04. Neither anticardiolipin nor LA are associated with carotid IMT, carotid plaque, nor coronary calcium by helical CT. In aCL positive patients carotid IMT was 0.57±0.01 vs. 0.58±0.01 in aCL negative patients (p=NS); carotid plaque 0.47±0.13 vs. 0.32±0.10 (p=NS); and coronary calcium 65.4±37.4 vs. 65.4±30.2 (p=NS). In LA positive patients, carotid IMT was 0.59±0.03 vs. 0.59±0.02 in LA negative patients (p=NS); carotid plaque 0.07±0.02 (SE) vs. 0.80±0.02 (SE) (p=0.06); and coronary calcium 28.1±3.7 (SE) vs. 85.7±2.6 (SE) (p=NS). Conclusion: Antiphospholipid antibodies are not associated with subclinical atherosclerosis (carotid IMR, carotid plaque, helical CT coronary calcium), but are associated with actual thrombotic sequelae (myocardial infarction).     

IgG binding to endothelial cells in systemic lupus erythematosus

Endothelial-associated IgG were determined in 20 patients with systemic lupus erythematosis (SLE)-8 of whom had a lupus anticoagulant (LA) and 6 a history of thrombosis. The binding of IgG present in patient plasma to cultured human endothelial cells was detected using radiolabeled staphylococcal protein A. Thirteen samples gave positive results and a significant association between endothelial-associated IgG and lupus anticoagulant was found (p less than 0.05). No statistically significant relationship with a previous history of thrombosis was found. These results suggest that the lupus anticoagulant may be directly involved in immune vascular injury induced by either antibodies or immune complexes in SLE.     

Prevalence of anti-cardiolipin, anti-beta2 glycoprotein I, and anti-prothrombin antibodies in young patients with epilepsy

PURPOSE: To measure anti-cardiolipin (aCL), anti-beta2 glycoprotein I (anti-beta2GPI), and anti-prothrombin (aPT) antibodies in young patients with epilepsy, and to correlate their presence with demographic data, clinical diagnoses, laboratory and neuroradiologic findings, and antiepileptic drugs (AEDs). METHODS: Sera from one hundred forty-two consecutive patients with epilepsy with a median age of 10 years were tested for aCL and anti-beta2GPI autoantibodies by solid-phase assays. aPT antibodies also were assayed in sera from 90 patients. Positive results were confirmed after a minimum of 6 weeks. Antinuclear antibodies (ANAs) and antibodies against extractable nuclear antigens (ENAs) also were tested. RESULTS: An overall positivity of 41 (28.8%) of 142 sera was found. Fifteen patients were positive for aCL, 25 for anti-beta2GPI, and 18 for aPT antibodies. Several patients (12%) displayed more than one specificity in their serum. Only one of these patients had a concurrent positivity for ANAs and ENAs. A predominance of younger patients was found in the antibody-positive group. All types of epilepsy were represented in the positive group. No relation between antibody positivity and AEDs was found. Diffuse ischemic lesions at computed tomography (CT)/magnetic resonance imaging (MRI) scans were present in higher percentages in patients who were antibody positive. No positive patient had a history of previous thrombosis or other features related to systemic lupus erythematosus (SLE), and no patient was born of a mother with SLE. CONCLUSIONS: Our study suggests a relation between epilepsy and aPL in young patients. A pathogenetic role for these autoantibodies cannot be excluded, and their determination might prove useful even from a therapeutic point of view.     

Antiphospholipid antibody ELISAs: survey on the performance of clinical laboratories assessed by using lyophilized affinity-purified IgG with anticardiolipin and anti-beta2-Glycoprotein I activity

Lupus anticoagulant (LA) and anticardiolipin (aCL) antibodies are the classical tests used to diagnose the antiphospholipid syndrome (APS). Unfortunately, since these are nonspecific and standardization is lacking, the results of laboratory work-ups upon which diagnosis are made are often misleading. The performance of clinical laboratories in detecting LA using lyophilised affinity purified immunoglobulin has been previously reported. The same material was used to investigate the inter-laboratory variability of aCL and anti-beta(2)-Glycoprotein I (beta(2)-GPI) antibody measurements. Laboratories were asked to test normal plasma spiked with purified IgG or distilled water in order to obtain 3 samples positive for aCL and anti-beta(2)-GPI at different antibody concentration (A, B and C) and 3 samples of normal plasma. Thirty-five laboratories participated and interpreted their test results. All performed an ELISA for IgG aCL antibodies, while 17 also tested samples using IgG anti-beta(2)-GPI antibody ELISA. Sensitivity and specificity were calculated on the basis of the responses provided by each laboratory. Overall, 99/105 samples were correctly interpreted as positive and 97/101 as negative for the presence of IgG aCL, corresponding to a sensitivity and specificity of 94% and 96%, respectively. Likewise, 46/51 samples were correctly defined as positive and 50/51 as negative for the presence of IgG anti-beta(2)-GPI corresponding to a sensitivity and specificity of 90% and 98%, respectively. A wide variability in results pertaining to the positive samples was found for aCL-ELISA (coefficient of variation of 79%, 59%, and 53% for samples A, B, and C, respectively) as well as for abeta(2)-GPI-ELISA (coefficient of variation of 85%, 95%, and 50% for samples A, B, and C, respectively). This was confirmed when the analysis was restricted to those centres using the same commercial kit. Median antibody concentrations reported by centres for positive samples were consistent with the prolongation of coagulation tests assessing lupus anticoagulant (LA). Among these, dRVVT showed a good sensitivity and linear correlation with aCL antibody concentration. In conclusion, on the whole this survey found correct interpretation of positive and negative samples by both ELISAs. Nonetheless the high variability of reported data remains a major problem that only a consensus on the part of laboratories and manufacturers to utilize standard, uniform materials and procedures can hope to overcome.     

Dilute aPTT prolongation by antiphospholipid antibodies in patients with liver cirrhosis

The behaviour of aPTT, as assessed by standard or diluted phospholipid mixture, was investigated in 20 patients suffering from liver cirrhosis. Standard aPTT was prolonged in 13 but it was corrected by 1:1 mixture with normal plasma. Dilute aPTT performed in samples mixed 1:1 with normal plasma and calculated by the difference in time between 1:80 and 1:5 phospholipid mixture was prolonged in 9 patients, who had also significantly higher titre of anticardiolipin antibodies (p less than 0.005). Unlike patients' plasma with normal dilute aPTT, the addition of 0.05 M PC/PS liposomes to patient's plasma with prolonged dilute aPTT significantly shortened dilute aPTT (p less than 0.001). This study shows the presence of antiphospholipid antibodies in some patients with liver cirrhosis; this seems to be responsible for the prolongation of dilute aPTT.