抗磷脂综合征165例临床特征与分型

目的 分析抗磷脂综合征(APS)的临床特征与分型.方法 根据2006年更新的APS分类诊断标准及新的临床亚型的定义,回顾性分析北京协和医院住院的165例APS患者的临床分型,总结患者的临床表现及治疗,并分析抗磷脂抗体与血栓的相关性.结果 165例患者中,男:女为1:3.不同临床亚型的分类包括确诊APS 116例(70.3%),可能APS 34例(20.6%),血清阴性APS 10例(6.1%),微血管性APS 5例(3.0%).124例(75.2%)合并其他疾病,其中113例(91.1%)合并自身免疫病,以系统性红斑狼疮常见(79.6%).合并血栓者121例(73.3%),其中静脉血栓68例(56.2%),以下肢深静脉血栓最常见.仅有狼疮抗凝物(LA)阳性和仅有抗心磷脂抗体(ACL)阳性患者的血栓发生率分别为86.0%和65.5%(P<0.05).61例APTT延长的患者中,LA阳性50例(82.0%),ACL阳性34例(55.7%).结论 根据APS临床表现可分为多种临床亚型.APS合并血栓以静脉血栓多见.LA阳性较ACL阳性的患者血栓发生率高.APTT延长与LA的相关性较强.     

抗膜联蛋白A2抗体在抗磷脂综合征中的作用

目的 研究抗膜联蛋白A2抗体在抗磷脂综合征(APS)、系统性红斑狼疮(SLE)的血栓/病态妊娠中的可能作用.方法 先用分子克隆方法表达纯化出重组膜联蛋白A2,然后以重组膜联蛋白A2为抗原,采用酶联免疫吸附试验(ELISA)法分别检测了,101例APS患者,41例SLE合并血栓患者,124例无血栓的SLE患者及120名健康人的血清中IgG型抗膜联蛋白A2抗体水平.结果 APS组和SLE合并血栓组的IgC型抗膜联蛋白A2抗体阳性率分别为21.8%,26.8%,均品著高于单纯SLE组(6.5%)(P值均<0.0.).IgG型抗膜联蛋白A2抗体与血栓/病态妊娠有关联(P<0.01).IgG型抗膜联蛋白A2抗体对血栓/病态妊娠诊断的敏感性、特异性、预测值分别为0.232、0.935、0.805.结论 IgG型抗膜联蛋白A2抗体与APS和SLE患者的血栓/病态妊娠表现相关,将有助于一些潜在的APS患者的诊断.     

抗磷脂综合征100例临床特征分析

目的探讨抗磷脂综合征（APS）的临床特征和血清学特点。方法回顾性分析总结100例APS患者的临床表现和免疫学改变。结果原发性APS（PAPS）37例，继发性APS（SAPS）63例，其中继发于系统性红斑狼疮（SLE）46例、狼疮样综合征14例。80％患者出现血管性血栓形成，其中静脉血栓43例、动脉闭塞18例、静脉血栓和动脉闭塞15例。52％为单一部位，32％有2个部位，15％多个部位血栓。56％单次，25％2次，19％多次血栓形成。血栓事件以下肢深静脉血栓（36％）、肺栓塞（30％）和脑卒中（26％）常见。51％（34／67）女性出现病态妊娠，胎死宫内占37％，习惯性自发性流产13％。血小板减少71例。抗心磷脂抗体（ACL）和狼疮抗凝物（LA）的阳性率分别为84％和58％。SLE继发APS组关节炎、白细胞减少、抗核抗体（ANA）阳性和低补体血症较PAPS多见。男性患者下肢深静脉血栓和LA阳性较多见；而女性白细胞减少、ANA阳性和ACL阳性较多见。结论APS以血栓形成及病态妊娠为特点．高滴度ACL和（或）LA阳性是其免疫学特征。其临床表现受基础疾病（SLE）和性别的影响而有不同。     

以反复肺动脉栓塞为首发症状的原发性抗磷脂综合征1例

正抗磷脂综合征(antiphospholipid syndrome,APS)是一种自身免疫状态,可以针对某些磷脂结合的血浆蛋白产生自身抗体,与血栓形成(包括静脉和动脉)、妊娠丢失等疾病发生风险相关。发生在没有其他自身免疫性疾病的情况下,称为原发性APS(primary APS,PAPS)。发生在系统性红斑狼疮或其他自身免疫性疾病患者的APS被称为继发性APS(secondary APS,SAPS)。APS特征是血液循环中抗磷脂抗体(antiphospholipid antibodies,APL)持续阳性,APL常用的临床实验室检测是狼     

系统性红斑狼疮合并继发性抗磷脂综合征1例

抗磷脂综合征(APS)为一种自身免疫性疾病,其特征为反复发作的动脉和(或)静脉血栓形成、反复自然流产和(或)“死胎”,伴有持续存在的抗磷脂抗体(aPL)阳性[1]。APS分为原发性和继发性两大类。系统性红斑狼疮(SLE)为继发性APS的主要原因。现将我院1例系统性狼疮合并APS报道如下。1     

抗磷脂抗体综合征的分类及临床表现

抗磷脂抗体综合征 (APS)的临床表现主要为 :1动、静脉血栓形成及栓塞 ;2血小板减少 ;3反复自发性流产或死胎。既所谓“三联症”。1.分类根据病因分类 :1原发性抗磷脂血栓综合征 (APL- T) :临床上原因不明的血栓与习惯性流产伴 APA持续阳性者。2继发性 APL- T:原因有 SL E和其他自身免疫性疾病、淋巴增生性疾病、肿瘤、感染 (细菌、病毒、原虫 )、炎症、药物等 ,已如前述。根据抗体分类 :1狼疮抗凝因子血栓综合征 (L A- T综合征 ) :伴 L A持续阳性 ,L A往往引起静脉血栓 (主要为 DVT和 PE) .2抗心磷脂抗体血栓综合征 (ACA- T综…     

抗磷脂抗体综合征肠系膜血管血栓形成的特点

目的 了解抗磷脂抗体综合征(APS)患者发生肠系膜血管血栓的特点.方法 在Pubmed及中国生物医学文献数据库(1983年1月至2007年7月)检索、分析、总结有关APS发生肠系膜血管血栓的病例报道.结果 共检索病例报道21例,男性13例,女性8例,年龄5个月～69岁,平均(37±17)岁.既往深静脉血栓形成病史3例(14%),自然流产史4例(19%).病程4 h～4个月.表现腹痛18例(86%)、便血或黑粪4例、呕吐3例、腹泻2例、呕血2例,其他有发热等表现.查体腹部压痛10例(48%)、腹膜刺激征5例(24%)、移动性浊音3例、肠鸣音减弱或缺如3例.10例行B超检查,其中3例(33%)检测到肠系膜血管血栓,13例行CT检查者中9例(69%)发现肠系膜血管血栓,4例行磁共振成像(MRI)检查及4例行多普勒超声均发现肠系膜血管血栓(100%),6例通过血管造影证实血栓形成.21例中抗心磷脂抗体阳性18例(86%),其中IgG型占14例(67%).16例行剖腹探查,发现肠缺血坏死者9例(56%).21例中肠系膜上静脉血栓17例(81%),肠系膜上动脉血栓4例(19%),肠系膜下动脉血栓1例(5%),其中肠系膜静脉血栓中7例同时存在门静脉血栓(33%).结论 APS肠系膜血管血栓以肠系膜上静脉为主,常同时存在门静脉血栓,男性略多,中青年略多,可有血栓或自然流产史,可急性起病或逐渐进展,常表现为肠梗阻、肠缺血坏死,IgG型抗心磷脂抗体阳性多见,多种影像学方法联合检测利于及时发现血栓,抗凝及必要时及时手术对多数患者有益.     

抗磷脂综合征相关心血管疾病的表现及新进展

抗磷脂综合征（APS）是以反复发生血栓事件和妊娠并发症以及抗磷脂抗体持续阳性为特点的一种系统性自身免疫性疾病。APS可以影响包括心血管系统在内的多个器官和系统,APS相关心血管疾病会给患者生命造成严重威胁。在2023年更新的美国风湿病学会（ACR）联合欧洲抗风湿病联盟（EULAR）APS分类标准中,将瓣膜病变纳入了APS的临床标准,这也提示应该重视APS合并的心血管疾病。本文将对APS合并的常见心血管疾病的表现及机制进行综述。     

抗磷脂综合征115例的临床特点及临床分类标准的演变和局限性的探讨

目的 研究抗磷脂综合征（APS）的临床特点，分析不同时期的APS的分类标准，以提高对这一疾病的认识。方法 回顾性分析1996-2006年在仁济医院根据不同时期的分类标准诊断的APS患者的临床和实验室特点。结果 1996-2006年满足至少1个分类标准的患者共120例，其中符合1988年Asherson分类标准者有101例，符合1999年Sapporo标准者为96例。符合2006年Sydney标准者为115例。在115例APS患者中，男女比例为1：10．5，平均病程为82．6个月，平均年龄为（41±12）岁。其中90例患者发生血栓事件，以深静脉血栓、脑梗死、皮肤血管为主。92例已婚有生育史的女性患者中。有46例发生病态妊娠。7例患者发生恶性APS。抗心磷脂抗体阳性86例，抗β2-糖蛋白Ⅰ（β2-GP Ⅰ）抗体阳性58例，狼疮抗凝物阳性27例。结论 常见的血栓部位为下肢深静脉、脑梗死和皮肤血管。Sydney标准增加抗β2-GP Ⅰ抗体作为一项实验室指标，提高了分类标准的敏感性，但是对于一些仅有血小板减少和实验室指标阳性的原发性APS患者的诊断存在局限性。另外，一些针对凝血因子的抗体对APS诊断的意义有待深入研究。     

非标准抗磷脂抗体对抗磷脂综合征的临床应用价值

目的 探讨抗磷脂酰胆碱抗体(aPC)、抗磷脂酰甘油抗体(aPG)和抗鞘磷脂抗体(aSM)检测在抗磷脂综合征(APS)的临床应用价值。方法 共纳入98例原发性APS患者(PAPS组),41例继发性APS患者(SAPS组),138例系统性红斑狼疮患者(SLE组)和55例健康体检者(HC组)。采用化学发光免疫试验(CLIA)检测血清抗心磷脂抗体(aCL)、抗β₂糖蛋白I抗体(aβ₂GPI);酶联免疫吸附试验(ELISA)检测aPC、 aPG和aSM。比较分析组间各指标的差异以及其与临床表现的相关性。结果 PAPS组的aPC IgM (1.47 U/mL)、aPG IgM (1.82 U/mL)、aSM IgM (20.97 U/mL)、aPG IgG (1.22 U/mL)、aSM IgG (14.56 U/mL)浓度高于SLE组(0.91、0.67、10.83、0.88、9.54 U/mL),差异有统计学意义(均P<0.05);SAPS组aPC IgM (2.00 U/mL)、aPG IgM (1.59 U/mL)、 aSM IgM (17...     

Clinical characteristics and thrombosis outcomes of paediatric antiphospholipid syndrome: analysis of 58 patients

The study aims to analyse the clinical and immunological manifestations of paediatric antiphospholipid syndrome (APS) in patients, based on the 2006 revised classification criteria of definite APS. Fifty-eight paediatric patients with APS were enrolled and analysed retrospectively. A total of 37 female and 21 male patients with a mean age of 14 ± 3 years at disease onset were included. Fourteen (24%) cases were primary APS, and 40 (69%) cases were secondary to systemic lupus erythaematosus (SLE). Anti-nuclear antibody (ANA) positivity and hypocomplementemia were more common in secondary APS than in primary APS. The most common manifestations of thrombosis were deep vein thrombosis of the lower extremities (25 cases, 37%). Non-thrombotic manifestations were mainly immunologic thrombocytopenia, autoimmune haemolytic anaemia, skin lesions, arthritis, pulmonary hypertension, heart valve vegetations and spontaneous abortion. LA, ACL and anti-β2GPI were positive in 42 (95%), 28 (64%) and 34 (77%) cases, respectively. Over half (23 cases, 52%) of the patients were triple-positive for antiphospholipid (aPL) antibodies. Among patients with single-positive LA and anti-β2GPI, the proportion with venous thrombosis was 100% (5 cases) and 0% (0 cases), respectively. The arterial thrombosis proportions were 22% (5 cases), 21% (3 cases) and 14% (1 case) in the triple-, double- and single-aPL-positive groups, respectively (P > 0.05). Fifty-three (91%) cases were followed up for 3 to 140 months, with a median time of 32 months. Seven (13%) cases had recurrences or appearances of thrombosis during follow-up, all of which were double- or triple-aPL positive. APS in the paediatric patients is mostly secondary to SLE. ANA positivity and hypocomplementemia are more common in secondary APS, but there are no differences in the other clinical manifestations between the primary and secondary APS groups. Deep vein thrombosis is the most common thrombotic event. Positive LA may increase the risk of venous thrombosis. Multiple-aPL positivity does not increase the proportion of thrombosis. Long-term anticoagulant or antiplatelet therapy is needed to prevent thrombosis recurrence in double- or triple-positive aPL cases.     

Central nervous system involvement in the antiphospholipid (Hughes) syndrome

The antiphospholipid (Hughes) syndrome (APS) is characterized by arterial and/or venous thrombosis and pregnancy morbidity in the presence of anticardiolipin antibodies and/or lupus anticoagulant. APS can occur either as a primary disorder or secondary to a connective tissue disease, most frequently systemic lupus erythematosus. Central nervous system (CNS) involvement is one of the most prominent clinical manifestations of APS, and includes arterial and venous thrombotic events, psychiatric features and a variety of other non-thrombotic neurological syndromes. In this review we focus on the common and some of the less common CNS manifestations that have been reported in association with antiphospholipid antibodies.     

Clinical characteristics and laboratory findings of 252 Chinese patients with anti-phospholipid syndrome: comparison with Euro-Phospholipid cohort

This study aims to characterize the Chinese Han patients with anti-phospholipid syndrome (APS) and compare the data with those of the Euro-Phospholipid cohort. We conducted a single center study consisting of 252 patients with definite APS from 2000 to 2015. We analyzed the clinical and laboratory characteristics of our cohort and compared the data with those of the Euro-Phospholipid cohort. Our cohort consisted of 216 females and 36 males, with a mean age at entry into this study of 41 years (range 11–74 years). Of these patients, 69 (27.4%) patients had primary APS, and 183 (72.6%) had secondary APS (SAPS), including 163 (64.7%) patients had systemic lupus erythematosus (SLE). Thrombotic events occurred in 190 (75.4%) patients, and the most common ones were deep vein thrombosis (40.1%) and stroke (23.8%), which were similar to the reports of the Euro-Phospholipid cohort. In contrast, our cohort had less pulmonary embolism (6.7%). Among 93 females with 299 pregnancy episodes, the rates of early (<10 weeks) and late fetal loss (≥10 weeks) were, respectively, 37.8% and 24.4%. The latter was significantly higher than that of the Euro-Phospholipid cohort. Moreover, 7 APS nephropathy patients (characterized histopathologically by thrombotic microangiopathy) and 8 catastrophic APS patients were found in our cohort. Anti-cardiolipin antibodies (aCL) were detected in 169 (67.1%) patients, lupus anti-coagulant (LA) was detected in 83 (32.9%), and anti-β2 glycoprotein I antibodies (anti-β2GPI) in 148 (58.7%) patients. These results show that some clinical manifestations of APS may vary among different racial groups.     

Prevalence and clinical significance of antiprothrombin antibodies in patients with systemic lupus erythematosus or with primary antiphospholipid syndrome

BACKGROUND AND OBJECTIVE: Antibodies to prothrombin (aII) have been identified in patients with antiphospholipid antibodies, but their clinical significance is not well known. The aim of our study was to investigate their prevalence and association with clinical manifestations of the antiphospholipid syndrome (APS) in patients with primary APS or with systemic lupus erythematosus (SLE). DESIGN AND METHODS: A series of 177 patients with autoimmune diseases was studied: 70 with primary APS and 107 with systemic lupus erythematosus. A control group of 87 healthy volunteers were included in the study. aII were investigated in sera by an ELISA, using human prothrombin as antigen fixed in irradiated polystyrene plates. RESULTS: aII prevalence in patients with autoimmune disease was 47% (57% and 40% in patients with primary APS or with SLE, respectively) significantly higher than in controls (5%) (p<0.0001). In the whole series, thrombotic events were more prevalent in patients with aII (45% vs 28%; p=0.02). Moreover, aII was found to be an independent risk factor for arterial thrombosis (OR=2.4; p=0. 04). Similarly, in patients with SLE, aII were associated with both arterial and venous thrombosis (35% vs 14%; p=0.01), although only IgG-aII (OR=3.7; p=0.01) had an independent value as risk factor for thrombosis. However, a relationship between aII and thrombosis was not found in primary APS. aII were associated with thrombocytopenia only in patients with primary APS (OR=6.7; p=0.007). INTERPRETATION AND CONCLUSIONS: aII seem to be a serological marker of thrombosis in autoimmune diseases, mainly in SLE patients and/or in the arterial territory.     

Antiphospholipid syndrome and the kidneys

OBJECTIVES: To study the relationship between antiphospholipid antibodies and kidney diseases. METHODS: We reviewed the medical literature from 1968 to 2005 using MEDLINE and the keywords antiphospholipid syndrome, anticardiolipin antibodies, lupus anticoagulant, hypertension, renal artery stenosis, renal vascular thrombosis, thrombotic microangiopathy, and glomerulonephritis. RESULTS: The renal manifestations of the antiphospholipid syndrome may result from thrombosis occurring at any location within the renal vasculature, that is, in the renal artery trunk or branches, intraparenchymal arteries and arterioles, glomerular capillaries, and the renal veins. The spectrum of these manifestations includes renal artery stenosis and/or malignant hypertension, renal infarction, renal vein thrombosis, thrombotic microangiopathy, increased allograft vascular thrombosis, and reduced survival of renal allografts. More recently nonthrombotic conditions like glomerulonephritis have also been reported. CONCLUSION: The kidney appears to be a major target organ in both primary and secondary APS. Early detection of renal involvement may improve the prognosis of these patients.     

The prevalence and clinical significance of inherited thrombophilic risk factors in patients with antiphospholipid syndrome

In this study, we evaluated common inherited thrombophilic risk factors in patients with antiphospholipid syndrome (APS), and reviewed relevant literature. Ninety-four APS patients with documented thrombosis, 40 patients with persistent antiphospholipid antibody (aPLA) positivity but without thrombosis, and healthy controls were screened. We found that inherited protein C, protein S, and antithrombin deficiencies were rare in APS patients. The presence of factor V Leiden G506A (FVL) mutation was significantly higher in APS patients with thrombosis compared to healthy controls (11.2% versus 4.9%, P = 0.0043). The prevalence of prothrombin G20210A mutation, however was not significantly increased in APS patients with thrombosis compared to patients without thrombosis (2.7% versus 1.25%, P = 0.67). Our literature review suggested that FVL mutation was associated with both arterial and venous thrombosis but prothrombin G20210A mutation does not seem to contribute much to thrombotic risk in patients with APS. In conclusion, the presence of FVL mutation may define a small but important subgroup of patients who had high risk of both venous and arterial thrombosis. Known thrombophilic risk factors however, may influence the development of thrombotic complications in approximately 10% of APS patients. These findings may indicate that thrombotic complications in APS patients are largely related with aPLA-mediated mechanisms.     

The 4G/5G polymorphism of the type 1 plasminogen activator inhibitor gene and thrombosis in patients with antiphospholipid syndrome

OBJECTIVE: To investigate the relationship between the 4G/5G polymorphism of the type 1 plasminogen activator inhibitor (PAI-1) gene and thrombotic manifestations in patients with antiphospholipid syndrome (APS). METHODS: We studied a total of 247 patients included in the following 4 groups: 70 patients with primary APS, 104 patients with systemic lupus erythematosus (40 with antiphospholipid antibodies [aPL] and clinical [secondary] APS, 13 with aPL but without clinical APS, and 51 with neither detectable aPL nor a history of thrombosis), 14 asymptomatic individuals with aPL, and 59 patients with thrombosis but without known thrombosis risk factors. A control group of 100 healthy individuals was also analyzed. PAI-1 4G/5G polymorphism was determined by polymerase chain reaction and endonuclease digestion. RESULTS: The allele frequency of 4G/5G in controls was 0.47/0.53. There were no differences in allele distribution among patient groups or between patients and controls. However, a higher frequency of the 4G allele was observed in APS patients with versus those without thrombosis (0.57 versus 0.39; P < 0.05) (odds ratio [OR] 2.83, 95% confidence interval [95% CI] 1.18-6.76). This higher frequency of the 4G allele was attributable to the higher frequency in patients with versus those without arterial thrombosis (0.64 versus 0.43; P < 0.01) (OR 5.96, 95% CI 1.67-21.32), while patients with venous thrombosis had an allele distribution similar to that of those without venous thrombosis (0.49 versus 0.50; P not significant). There was a trend toward higher PAI-1 antigen and activity levels in APS patients and controls with the 4G/4G genotype, but this did not reach statistical significance. CONCLUSION: The presence of the 4G allele of the 4G/5G polymorphism of the PAI-1 gene may be an additional risk factor for the development of arterial thrombosis in APS.     

Antiphospholipid syndrome in Asians: clinical manifestations,serological markers and outcome of the National University of Singapore/National University Hospital antiphospholipid cohort

Background: There is a paucity of studies on antiphospholipid syndrome (APS) in Asian patients. Aim: This is the first study in Singapore to describe the clinical features, serological markers and outcomes of one of the largest cohort of APS patients in South‐east Asia. Method: One hundred and forty‐six patients were studied. Results: Within the study group, 89 were primary APS and 57 secondary APS. Age range: 16–84 years (mean Age: 50.1 years). Male : female ratio: 1 : 2.1. Racial distribution: Chinese, 69.2%; Malays, 18.5%; Indians, 11.7%. Systemic lupus erythematosus was the commonest disease associated in 48 patients (32.9%), while 17 (11.6%) had lupus‐like disease. Eighty‐two (56.2%) patients had arterial thrombosis, 37 (25.3%) patients had venous thrombosis, 14 (9.6%) had arterial and venous thrombosis while 17 (11.6%) had obstetric manifestations; 28.8% had thrombocytopenia. Clinical manifestations were diverse with neurological (49.3%), cardiac (40%), renal (23.6%) involvement. There were also several unusual presentations. Recurrent thrombosis occurred in 24.6%. Two had catastrophic APS and there were 12 deaths (9.6%). Antiphospholipid antibody testing included lupus anticoagulant, serum aCL IgG, IgM and IgA, anti‐β2 glycoprotein I (aβ2‐GPI) IgG, IgM, and IgA. The serological positivity rates of the various antiphospholipid antibodies were reported. aβ2‐GPI was positive in 67% of those tested, of which aβ2‐GPI IgA was the most common subtype. The presence of the aβ2‐GPI was associated with recurrent venous thrombosis. Conclusion: The clinical manifestations of APS in Asian patients were diverse and multisystemic. Recurrent thrombosis rate was high with significant morbidity and mortality.     

Thrombotic manifestations of the antiphospholipid syndrome in patients with malignancies

The presence of antiphospholipid antibodies has been reported in a large variety of patients with malignancies. Many case reports and reviews have appeared indicating that the presence of the antiphospholipid antibodies is related to thrombotic associations with the antiphospholipid syndrome (APS) in a proportion of these patients. We investigated the frequency of the thrombotic manifestations in 58 patients demonstrating antiphospholipid antibodies and with a history of neoplasia, including haematologic and lymphoproliferative malignancies. Antiphospholipid antibodies were detected by clotting assay [lupus anticoagulant (LAC)] or by enzyme-linked immunosorbent assay [anticardiolipin antibodies (aCL)] according to the Sapporo criteria. Patients, 39/58, suffered from solid tumours and 19/58 patients from malignant haematologic or lymphoproliferative diseases. One patient was suffering simultaneously from two solid tumours and a malignant lymphoma. Among the patients with solid tumours, 18/39 (46%) patients had thromboembolic complications of the antiphospholipid syndrome. Among the patients with haematologic and lymphoproliferative malignancies, only 6/19 (32%) suffered from thromboembolic complications. There was, however, no relation between the titres of aCL antibodies and the clinical manifestations. The presence, but not the titres, of antiphospholipid antibodies may identify a subset of cancer patients with a high risk of developing thrombotic complications. The frequency of thrombosis, however, is lower in aPL-positive patients with lymphoproliferative and haematological malignancies.     

Thrombotic thrombocytopenic purpura with severe ADAMTS-13 deficiency in two patients with primary antiphospholipid syndrome

Arterial thrombotic events, thrombocytopenia, and hemolytic anemia with schistocytes may be encountered in the setting of both thrombotic thrombocytopenic purpura (TTP) and primary antiphospholipid syndrome (APS). We report 2 cases of TTP occurring in patients with definite primary APS. We also describe the results of tests for ADAMTS-13 activity in 20 consecutive patients with primary APS, as well as tests for antiphospholipid antibodies in 26 patients who had TTP, severe ADAMTS-13 deficiency, and ADAMTS-13-inhibiting antibodies. In both of the patients with primary APS and TTP, ADAMTS-13 activity was undetectable, and ADAMTS-13-inhibiting antibodies were present. None of the 26 patients with TTP and severe ADAMTS-13 deficiency was positive for the lupus anticoagulant. One of these patients had a low level of anticardiolipin antibodies (22 IgG phospholipid units). In the 20 patients with primary APS, mean ADAMTS-13 activity was 116% (range 44-250%), and no severe deficiency (< 5%) was observed. Our findings suggest that primary APS must be added to the list of autoimmune disorders that can be complicated by TTP.