Correlations of anti-cardiolipin antibody and anti-β2 glycoprotein I antibody with ischemic stroke in patients with systemic autoimmune diseases / 中国基层医药

Objective:To correlate anti-cardiolipin antibody (aCL) and anti-β2 glycoprotein I antibody (aβ2GPI) with ischemic stroke (IS) in patients with systemic autoimmune diseases (SADs).Methods:A total of 104 patients with SADs who received treatment in the Affiliated Hospital of North Sichuan Medical College during January to December 2019 were included in this study. They were divided into two groups whether they had IS (IS group, n = 42) or not (non-IS group, n = 62). aPL positive rate was qualitatively compared between the IS and non-IS groups. aCL and aβ2GPI expression levels were quantitatively compared between the IS and non-IS groups. Logistic regression analysis was performed to evaluate the risk factors for IS in patients with SADs. Results:aPL positive rate in the IS group was significantly higher than that in the non-IS group [61.9% (26/42) vs. 40.3% (25 /62), χ2 = 4.66, P = 0.031]. The aCL-IgM and aβ2GPI-IgM levels in the IS group were (22.82 ± 27.27) RU/mL and (18.70 ± 23.95) RU/mL, respectively, which were significantly higher than those in the non-IS group [(13.34 ± 8.43) RU/mL, (7.61± 5.80) RU/mL, t = -2.18, -2.76, P = 0.034, 0.009]. Logistic regression analysis showed that aPL is an independent risk factor for IS ( P = 0.037). Conclusion:aCL and aβ2GPI are closely related to the occurrence of IS and are the independent risk factors for IS in patients with SADs.

In vivo evidence of angiogenesis inhibition by ß2-glycoprotein I subfractions in the chorioallantoic membrane of chicken embryos

The vascular network expansion and functioning are important factors affecting normal intra-uterine fetal development. This study addressed the previously reported antiangiogenic potential of beta-2-glycoprotein I (β2GPI) in vivo in the chick embryo model of angiogenesis. The effects of two naturally occurring β2GPI forms on the development of the chorioallantoic membrane (CAM) vessels and the chicken embryo were investigated. β2GPI monomers and dimers were obtained by fractioned purification and characterized using SDS-PAGE, immunoblot, and ELISA. The egg exposure was performed by injection of small volumes of 2.5 µg/mL solutions of the β2GPI subfractions. Angiogenesis was evaluated through quantitative measurements of vascular architecture parameters in the captured CAM images, using computational analysis of texture contrasts and computer vision techniques. Quantitative information was assigned to the CAM vasculature modifications. In vivo, the β2GPI dimer completely halted the formation of CAM vessels and led to embryo death after 48 h of exposure. The β2GPI monomer allowed the embryo to develop up to the 10th day, despite early changes of CAM vessels. The impaired normal vessel growth proceeded as a self-limited effect. The β2GPI monomer-exposed eggs showed reduced vascularization on the 6th day of incubation, but embryos were viable on the 10th day of incubation, with ingurgitated CAM vessels implying sequelae of the angiogenesis inhibition. Both subfractions impaired CAM vasculature development. The β2GPI dimer proved to be largely more harmful than the β2GPI monomer. β2GPI modification by cleavage or dimerization may play a role in angiogenesis control in vivo.

Clinical and laboratory characteristics of Brazilian versus non-Brazilian primary antiphospholipid syndrome patients in AntiPhospholipid Syndrome Alliance for Clinical Trials and InternatiOnal Networking (APS ACTION) clinical database and repository

Abstract Background: Antiphospholipid syndrome (APS) is characterized by episodes of thrombosis, obstetric morbidity or both, associated with persistently positive antiphospholipid antibodies (aPL). Studying the profile of a rare disease in an admixed population is important as it can provide new insights for understanding an autoimmune disease. In this sense of miscegenation, Brazil is characterized by one of the most heterogeneous populations in the world, which is the result of five centuries of interethnic crosses of people from three continents. The objective of this study was to compare the clinical and laboratory characteristics of Brazilian vs. non-Brazilian primary antiphospholipid syndrome (PAPS) patients. Methods: We classified PAPS patients into 2 groups: Brazilian PAPS patients (BPAPS) and PAPS patients from other countries (non-BPAPS). They were compared regarding demographic characteristics, criteria and non-criteria APS manifestations, antiphospholipid antibody (aPL) profile, and the adjusted Global Antiphospholipid Syndrome Score (aGAPSS). Results: We included 415 PAPS patients (88 [21%] BPAPS and 327 [79%] non-BPAPS). Brazilian patients were significantly younger, more frequently female, sedentary, obese, non-white, and had a higher frequency of livedo (25% vs. 10%, p < 0.001), cognitive dysfunction (21% vs. 8%, p = 0.001) and seizures (16% vs. 7%, p = 0.007), and a lower frequency of thrombocytopenia (9% vs. 18%, p = 0.037). Additionally, they were more frequently positive for lupus anticoagulant (87.5% vs. 74.6%, p = 0.01), and less frequently positive to anticardiolipin (46.6% vs. 73.7%, p < 0.001) and anti-ß2-glycoprotein-I (13.6% vs. 62.7%, p < 0.001) antibodies. Triple aPL positivity was also less frequent (8% vs. 41.6%, p < 0.001) in Brazilian patients. Median aGAPSS was lower in the Brazilian group (8 vs. 10, p < 0.0001). In the multivariate analysis, BPAPS patients still presented more frequently with livedo, cognitive dysfunction and sedentary lifestyle, and less frequently with thrombocytopenia and triple positivity to aPL. They were also less often white. Conclusions: Our study suggests a specific profile of PAPS in Brazil with higher frequency of selected non-criteria manifestations and lupus anticoagulant positivity. Lupus anticoagulant (not triple positivity) was the major aPL predictor of a classification criteria event.

Antiphospholipid and Antinuclear Antibodies in Children with Idiopathic Epilepsy: A 2-Year Prospective Study

Anti-phospholipid syndrome in seven leprosy patients with thrombotic events on corticosteroid and/or thalidomide regimen: insights on genetic and laboratory profiles

Abstract INTRODUCTION Corticosteroids and/or thalidomides have been associated with thromboembolism events (TBE) in multibacillary (MB) leprosy. This report aimed to determine genetic and laboratory profiles associated with leprosy and TBE. METHODS Antiphospholipid antibodies (aPL), coagulation-related exams, prothrombin and Leiden's factor V mutations, and ß2-glycoprotein-I (ß2GPI) Val247Leu polymorphism were assessed. RESULTS Six out of seven patients with leprosy were treated with prednisone and/or thalidomide during TBE and presented at least one positive aPL. All patients presented ß2GPI polymorphism, and one showed prothrombin mutation. CONCLUSIONS Corticosteroid or thalidomide adverse effects and aPL and ß2GPI polymorphisms may cause TBE in patients with MB leprosy.

A potent multivalent vaccine for modulation of immune system in atherosclerosis: an in silico approach

PURPOSE: Atherosclerosis is classically defined as an immune-mediated disease characterized by accumulation of low-density lipoprotein cholesterol over intima in medium sized and large arteries. Recent studies have demonstrated that both innate and adaptive immune responses are involved in atherosclerosis. In addition, experimental and human models have recognized many autoantigens in pathophysiology of this disease. Oxidized low-density lipoproteins, beta2 glycoprotein I (beta-2-GPI), and heat shock protein 60 (HSP60) are the best studied of them which can represent promising approach to design worthwhile vaccines for modulation of atherosclerosis. MATERIALS AND METHODS: In silico approaches are the best tools for design and evaluation of the vaccines before initiating the experimental study. In this study, we identified immunogenic epitopes of HSP60, ApoB-100, and beta-2-GPI as major antigens to construct a chimeric protein through bioinformatics tools. Additionally, we have evaluated physico-chemical properties, structures, stability, MHC binding properties, humoral and cellular immune responses, and allergenicity of this chimeric protein by means of bioinformatics tools and servers. RESULTS: Validation results indicated that 89.1% residues locate in favorite or additional allowed region of Ramachandran plot. Also, based on Ramachandran plot analysis this protein could be classified as a stable fusion protein. In addition, the epitopes in the chimeric protein had strong potential to induce both the B-cell and T-cell mediated immune responses. CONCLUSION: Our results supported that this chimeric vaccine could be effectively utilized as a multivalent vaccine for prevention and modulation of atherosclerosis.

Performance of Automated Chemiluminescence Assay for Antiphospholipid Antibody Testing

BACKGROUND: Detection of antiphospholipid antibodies (aPL) can be considered problematic due to assay variability and reagent sensitivity, high false-positive and false-negative rates, and lack of assay standardization. Therefore, utilizing an automated system can improve reproducibility and reduce interlaboratory variation. Here, we evaluated the analytical performance of the new automated ACL AcuStar chemiluminescence assay (Instrumentation Laboratory, USA). This was compared to the results of a panel analyzed with the QUANTA Lite ELISA (INOVA Diagnostics Inc., USA). METHODS: We evaluated the inter-assay precision, linearity, and carry-over between the two methods, ACL and ELISA. A reference range study for each of the anticardiolipin (aCL) and anti-beta2 glycoprotein-I (abeta2GPI) IgG and IgM antibodies were performed using 135 healthy patient samples, which served as controls. We then compared the accuracy among the AcuStar and ELISA systems via four aPL tests. For this comparison, 69 patient samples suspected of an autoimmune disorder were used as the experimental panel. RESULTS: The AcuStar analyzer showed excellent precision, linearity, and carry-over for all four assays. The calculated cutoff values were 20.3 U/mL for aCL IgG, 20.3 U/mL for aCL IgM, 26.3 U/mL for abeta2GPI IgG, and 11.9 U/mL for abeta2GPI IgM. The consensus between AcuStar and ELISA results were generally comparable. Total agreement varied between 82.6% and 95.7%, and kappa values showed moderate to good agreement. CONCLUSIONS: Our study demonstrates that the new AcuStar chemiluminescence assay showed better performance. This automated system leads to improved reproducibility and reduces interlaboratory variability.

The evaluation of clinical value of antiphospholipid syndrome related autoantibodies / 中华检验医学杂志

Objective To evaluate the clinical application value of anti-β2 glycoprotein I ( anti-β2 GPI) and anti-cardiolipin antibodies ( ACA ) in the patients with antiphospholipid syndrome ( APS).Methods Serum levels of anti-β2GPI(IgG) and ACA(IgA, IgG, IgM) were determined by enzyme linked immunosorbent assay ( ELISA ) in 53 patients with APS , 27 patients with SLE accompanied by APS , 55 patients with simple SLE , 46 patients with other autoimmune diseases and 40 healthy controls.The sensitivity and specificity of anti-β2 GPI and ACA for the diagnosis of APS and the correlation of serum anti-β2 GPI and ACA-IgG levels were analyzed.The cases were identified in the Affiliated Hospital of Qingdao University during 2012.1 to 2014.2 and the data were analyzed with χ2 test, Mann-Whitney U test and Spearman correlation.Results The positive rates and serum levels of anti-β2 GPI, ACA-IgG/M, ACA-IgG, ACA-IgM were significantly higher in the APS group [77.4%(41/53), 81.1%(43/53), 56.6%(30/53), 52.8%(28/53);14.1 AU/ml, 19.6 U/ml, 17.9 U/ml] than those in the simple SLE group [16.4%(9/55), 32.7%(18/55), 20.0%(11/55), 18.2%(10/55); 4.9 AU/ml, 9.4 U/ml, 8.7 U/ml, χ2 =40.4, 25.7, 15.4, 14.2;U=255.0, 632.5, 476.5, P<0.01], other autoimmune diseases group[0%(0/46), 4.3%(2/46), 2.2%(1/46), 2.2%(1/46); 3.2 AU/ml, 2.6 U/ml, 3.4 U/ml, χ2 =60.7, 58.6, 33.9, 30.5;U=53.5, 87.0, 66.0, P<0.01] and healthy controls [0%(0/40), 2.5%(1/40), 0%(0/40), 2.5%(1/40);3.0 AU/ml, 3.5 U/ml, 2.9 U/ml, χ2 =55.3, 56.5, 33.4, 26.9;U=61.0, 124.0, 152.0, P <0.01 ] separately.The positive rate and serum level of ACA-IgA in the APS group [18.9%(10/53), 11.7 U/ml] were significantly higher than that in the other autoimmune disease group [2.2%(1/46), 2.9 U/ml,χ2 =6.9, U=581.0, P<0.01] and healthy controls[2.5%(1/40),2.1 U/ml,χ2 =4.4,U=764.0,P<0.05] separately.The specificity of anti-β2 GPI (83.6%) for APS diagnosis was significantly higher than that of ACA (67.3%, χ2 =4.0,P<0.05).Conclusions anti-β2 GPI, ACA-IgG and ACA-IgM, have higher clinical application value in the APS diagnosis and identification of SLE with or without APS than ACA-IgA.The specificity of anti-β2 GPI for APS diagnosis is higher than that of ACA.

Relationship between the valine/leucine247 polymorphism of apolipoprotein H gene and generation of antiphospholipid antibodies in patients of Han nationality with systemic lupus erythematosus in Wenzhou region / 中华皮肤科杂志

Objective To study the relationship between the valine/leucine247 (817G/T) polymorphism in exon 7 of apolipoprotein H (apoH) gene and the generation of antiphospholipid (APL)antibodies in patients of Han nationality with systemic lupus erythematosus (SLE) in Wenzhou region.Methods This study included 165 patients with SLE and 160 healthy controls of Han nationality in Wenzhou region.Venous blood samples were obtained from all of the subjects followed by the isolation of blood plasma,sera and white blood cells.PCR and DNA sequencing were carried out to assess the Leu/Va1247 polymorphism in apoH gene.Lupus anticoagulant (LAC) was detected by Russell viper venom time (RVVT) assay.Enzyme-linked immunosorbent assay (ELISA) was carried out to quantify the serum levels of anti-β2-glycoprotein Ⅰ (GPI) antibodies and anticardiolipin antibodies (ACA).Chi-square test was carried out to compare the 817G/T polymorphism between the patients and controls,and Logistic regression analysis to evaluate the correlation between the 817G/T polymorphism and production of antiphospholipid antibodies.Results There were significant differences between the patients and controls in the genotype distribution and allele frequency at position 817 of apoH gene (both P ＜ 0.01).The TT,GT genotypes and T allele were more frequent,while GG genotype and G allele were less frequent,in the patients than in the controls.The GT genotype at position 817 was a risk factor for the production of LAC (P＜ 0.05,OR =2.33,95％CI =1.18-4.59),anti-β2GPl antibodies(P＜ 0.01,OR =5.92,95％CI =2.61-13.46) and ACA(P＜ 0.05,OR =2.52,95％CI =1.22-5.24),and the TT genotype was associated with an increased frequency of anti-β2GPI antibodies (P ＜ 0.01,OR =5.84,95％CI =1.69-20.20).Conclusions The 817G/T(Leu/Va1247) polymorphism in exon 7 of apoH gene is associated with the generation of APL antibodies in patients of Han nationality with SLE in Wenzhou region.The TT and GT genotypes at position 817 of apoH gene appear to be a risk factor for the production of APL antibodies.

Síndrome antifosfolípido: generalidades y diagnóstico / Antiphospholipid syndrome: clinical and laboratory diagnosis

Resumen: El síndrome antifosfolípido ha sido un tema de investigación continua en diferentes áreas de la medicina. El diagnóstico clínico y de laboratorio se realiza teniendo en cuenta los consensos inter-nacionales de Sapporo (1999) y Sydney (2006), los cuales dan las pautas para identificar y caracterizar el síndrome antifosfolípido. El objetivo primordial de este artículo, es describir los avances científicos en el estudio del síndrome antifosfolípido, los criterios actuales de clasificación, el papel de los anti-cuerpos anticardiolipina, anti β2 glicoproteína I y el anticoagulante lúpico, así como los mecanismos patogénicos e inmunológicos en los que están involucrados estos anticuerpos. También se describen algunas de las manifestaciones clínicas relacionadas y los procedimientos diagnósticos utilizados ac-tualmente para su identificación.

Abstract: Antiphospholipid syndrome has been a topic of ongoing research in different areas of medicine.Clinical and laboratory diagnosis are performed taking into account international guidelines to identify and characterize antiphospholipid syndrome. The primary objective of this article is to describe scientific advances in the study of the antiphospholipid syndrome, current classification criteria, the role of anticardiolipin antibodies, anti-β2 glycoprotein I and lupus anticoagulant, and to describe the pathogenic and immunological mechanisms in which these antibodies are involved. Furthermore, this article describes some of the associated clinical and diagnostic procedures currently used for antiphospholipid syndrome identification.

Posible papel de la β 2 glicoproteína I y la apoptosis durante la diseminación intermolecular de epítopes en lupus eritematoso sistémico / Possible role of β 2-glycoprotein I and apoptosis during intermolecular epitope spreading in systemic lupus erythematous

El lupus eritematoso sistémico (LES) es una enfermedad caracterizada por la pérdida de la tolerancia hacia antígenos propios que conlleva a la aparición de autoanticuerpos contra antígenos nucleares y daño de órganos asociado. Durante la apoptosis se expone al sistema inmune a múltiples antígenos nucleares y se piensa que alteraciones en la remoción de cuerpos apoptóticos pueden iniciar o perpetuar una respuesta autoinmune. Otra fuente de material nuclear expuesto al medio extracelular son las denominadas micropartículas, las cuales son liberadas de diferentes células no solo durante la apoptosis sino también durante la activación celular o el estrés mecánico. Se ha demostrado que los pacientes con LES presentan autoanticuerpos varios años antes de la fase clínica de la enfermedad, y esta aparición de autoanticuerpos tiende a seguir un curso predecible, con acumulación progresiva de autoanticuerpos específicos. Esta aparición consistentemente ordenada de autoanticuerpos, precediendo por varios años la aparición de la enfermedad clínica, apoya fuertemente las teorías de diseminación de epítopes en LES humano. Varios modelos múridos han tratado de reproducir la enfermedad humana utilizando cuerpos apoptóticos pero sin resultados contundentes. Un reciente modelo animal logra reproducir más fielmente la secuencia de autoanticuerpos y las manifestaciones clínicas del LES al utilizar a la β2GP-I como inmunógeno potenciado por una respuesta de célula T inducida por lipopolisacárido. Las micropartículas, rodeadas de fosfatidilserina y cargadas de material nuclear incluyendo DNA extracelular antigénicamente activo, son asimismo candidatas ideales para servir de plataforma para la diseminación de epítopes en un medio inflamatorio, con la posterior aparición secuencial de autoanticuerpos específicos patogénicos.

Systemic lupus erythematosus (SLE) is a disease characterized by loss of tolerance to self-antigens leading to the development of autoantibodies against nuclear antigens and organ damage. During apoptosis, immune system is exposed to multiple nuclear antigens and is thought that alterations in the removal of apoptotic bodies could start or perpetuate an autoimmune response. Another source of nuclear material exposed to extracellular medium are called microparticles, which are released from various cells not only during apoptosis but also during cell activation or mechanical stress. It has been shown that patients with SLE already have autoantibodies several years before clinical phase of disease, and this appearance of autoantibodies tends to follow a predictable course, with progressive accumulation of specific autoantibodies. This steadily orderly appearance of autoantibodies preceding for several years the onset of clinical disease strongly supports theories of spreading epitopes in human SLE. Several mouse models have tried to replicate the human disease using apoptotic bodies but without conclusive results. A recent animal model can reproduce more closely the sequence of autoantibodies and clinical manifestations of SLE using the β2-glycoprotein I (β2GP-I) as an immunogen powered by a lipopolysaccharide induced T cell response. Microparticles, surrouded by phosphatidylserie and nuclear material loaded including antigenically active extracellular DNA, are also ideal candidates to serve as a.

Characterization of antiphospholipid antibodies in chronic hepatitis B infection / 대한혈액학회지

BACKGROUND: Many infections are associated with antiphospholipid antibodies (aPLs). The purpose of this study was to investigate the prevalence, persistence, clinical significance, and characteristics of aPLs in hepatitis B virus (HBV)-infected patients. METHODS: This study included 143 patients with HBV infection and 32 healthy individuals as controls. The presence of anticardiolipin antibodies (aCL Ab), anti-beta2-glycoprotein I antibodies (beta2GPI Ab), and lupus anticoagulant (LA) was assessed. RESULTS: The total prevalence of aPLs in HBV-infected patients was 12.6% (18 of 143). Of these 18 patients, 15 had low to medium titers of aCL Ab (10 with IgM, 4 with IgG, and 1 with both isotypes). beta2GPI Ab and LA were detected in 3 (2.1%) and 2 (1.4%) patients with HBV infection, respectively. In follow-up specimens from 14 patients with elevated levels of aCL Ab or beta2GPI Ab, 10 (71.4%) showed the persistent presence of aPLs. No clinical manifestations related to aPLs were identified. CONCLUSION: In HBV-infected patients, the most frequently detected antiphospholipid antibodies were IgM aCL Ab, which have a weak association with the clinical manifestations of APS. Unlike the transient presence reported for other infection-associated aPLs, most aPLs were persistently detected over a 12-week period in patients with HBV infection.

Polimorfismo Val247Leu do gene β2-glicoproteína 1 pode justificar a gênese de anticorpos antiβ2GP1 e síndrome do anticorpo antifosfolípide na hanseníase multibacilar / Val247Leu polymorphism of β2 glycoprotein 1 gene may justify the genesis of anti β2GP1 antibodies and Antiphospholipid Syndrome in Multibacillary Leprosy

FUNDAMENTOS - Anticorpos antifosfolípides (AAF), como antiβ2GP1 (β2-glicoproteína 1), são descritos na hanseníase multibacilar (MB) sem, contudo, caracterizar a síndrome do anticorpo antifosfolípide (SAF), constituída por fenômenos tromboembólicos (FTE). A mutação Val247Leu no V domínio da β2GP1 - substituição da leucina por valina - expõe epítopos crípticos com consequente formação de anticorpos antiβ2GP1. OBJETIVO: Avaliar a associação do polimorfismo Val247Leu do gene β2GP1 com títulos de anticorpos antiβ2GP1 na hanseníase. MÉTODO: O polimorfismo Val247Leu foi detectado por PCR-RFLP, e os títulos de anticorpos antiβ2GP1, por Elisa. RESULTADOS: O genótipo Val/Val estatisticamente predominou no grupo de hansênicos, em relação ao controle. Embora maiores títulos de anticorpos antiβ2GP1 IgM estivessem alocados no grupo MB com genótipos Val/Val e Val/Leu, não houve diferença estatística em relação ao genótipo Leu/Leu. Dos sete pacientes MB com FTE, quatro apresentaram heterozigose, e três Val/Val homozigose. CONCLUSÃO: A prevalência do genótipo Val/Val no grupo de hansênicos pode justificar parcialmente a presença de anticorpos antiβ2GP1 na forma MB. A heterozigose ou homozigose Val/Val nos sete pacientes com hanseníase MB e FTE corroboram a implicação de expressão fenotípica anômala da β2GPl e formação de anticorpos antiβ2GPl, com consequente FTE e SAF.

BACKGROUND - Multibacillary (MB) leprosy may be manifested with antiphospholipid antibodies (aPL), among which anti-β2GP1 (β2-glycoprotein 1). High titers of aPL are associated with APS (Antiphospholipid Syndrome), characterized by thrombosis. The mutation Val247Leu in the domain V of β2GP1 exposes hidden epitopes with consequent development of anti-β2GP1 antibodies. OBJECTIVE: To evaluate the Val247Leu polymorphism of β2GP1 gene and its correlation with anti-β2GP1 antibodies in leprosy patients. METHODS: The Val247Leu polymorphism was performed by PCR-RFLP and anti-β2GP1 antibodies were measured by ELISA. RESULTS: The genotypic Val/Val was more prevalent in the leprosy group, compared to controls. Regarding the 7 MB patients with APS, four presented heterozygosis and three, Val/Val homozygosis. Although higher titrations of anti-β2GP1 IgM antibodies were seen in MB leprosy group with Val/Leu and Val/Val genotypes, there was no statistical difference when compared to Leu/Leu genotype. CONCLUSION: The prevalence of Val/Val homozygosis in leprosy group can partially justify the presence of anti-β2GP1 IgM antibodies in MB leprosy. The description of heterozygosis and Val/Val homozygosis in 7 patients with MB leprosy and thrombosis corroborates the implication of anomalous phenotype expression of β2GP1 and development of anti-β2GP1 antibodies, with consequent thrombosis and APS.

Activated protein C resistance and lupus anticoagulant activity induced by plasma and purified monospecific human IgG anti-β2-glycoprotein-I antibodies / Resistencia a la proteína C activada y actividad de anticoagulante lúpico inducidas por plasma y por anticuerpos purificados humanos del IgG anti β2-glicoproteína I

ABSTRACT Introduction. We investigated the activated protein C resistance (APCR) phenotype and the lupus anticoagulant (LA), activity induced by anti-β2-glycoprotein-I (anti-β2GP-I) antibodies. Patients and methods. We studied plasma and sera samples from 29 patients with persistently positive anti-β2GP-I: 22 with thrombosis (12 with primary APS, 10 with APS secondary to SLE) and seven without thrombosis (all with SLE); 25 healthy subjects were studied as controls. We detected anticardiolipin antibodies (ACA); IgG (and its subclasses) and IgM anti-β2GP-I, on irradiated and non-irradiated plates by ELISA. APCR was assessed by the activated partial thromboplastin time (APTT)-based assay and by the modified test. The FV Leiden mutation was studied by PCR. LA determination included screening and confirmatory dRVVT. Serum anti-β2GP-I were affinity purified on sepharose columns and their isotype, subclass, and reactivity against various antigens were studied by ELISA. Results. We found that titers of IgG anti-β2GP-I on irradiated plates were higher than on non-irradiated plates (p = 0.002), IgG2 was the predominant subclass. Fifteen patients (13 with thrombosis) had LA and 15 (also 13 with thrombosis) induced the APCR phenotype. Eleven (all with thrombosis) had both. Two patients were heterozygous for the Leiden mutation. Two purified antibodies, monospecific for β2GP-I, induced an in vitro APCR phenotype and LA activity. Conclusions. Our results seem to indicate that the inhibition of the APC anticoagulant function by IgG2 anti-β2GP-I with LA activity may be one of the responsible mechanisms of thrombophilia in patients with APS.

Introducción. Investigamos la resistencia a la proteína C activada (RPCA) y la actividad de anticoagulante lápico (AL), inducidas por anticuerpos anti-β2-glicoproteína-I (anti-β2GP-I). Pacientes y métodos. Estudiamos los plasmas y sueros persistentemente positivos para anti-β2GP-I de 29 pacientes: 22 tuvieron trombosis (12 con síndrome de antifosfolípidos (SAF) primario y 10 con SAF secundario a lupus erítematoso generalizado (LEG)) y siete sin trombosis (todos con LEG). Como controles estudiamos 25 sueros de personas clínicamente sanas. Detectamos anticuerpos anticardiolipina, anti-β2GP-I IgG (y sus subclases) e IgM por ELISA en placas irradiadas y no irradiadas. Evaluamos la RPCA por medio del tiempo parcial de tromboplastina activada y por la prueba modificada. Estudiamos la mutación FV de Leiden por PCR y el anticoagulante lápico con el método de dRVVT screening y confirmatorio. Después de purificar los anti-β2GP-I séricos con una columna de antígeno unido a sefarosa, analizamos por ELISA sus isotipos, subclases y reactividad contra β2GP-I y algunos fosfolípidos. Resultados. Los títulos de anti-β2GP-I IgG fueron más altos en placas irradiadas que en no irradiadas (p = 0.002), predominó la subclase IgG2. Quince plasmas (13 de pacientes con trombosis) tuvieron AL y 15 (13 también de pacientes con trombosis) indujeron el fenotipo de RPCA. Once plasmas (todos de pacientes con trombosis) indujeron ambas actividades. Dos pacientes fueron heterocigotos para la mutación de Leiden. Dos anticuerpos purificados monoespecíficos para β2GP-I indujeron el fenotipo de la RPCA y la actividad de AL in vitro. Conclusiones. Nuestros resultados sugieren que la RPCA, inducida por los anti-β2GP-I que concomitantemente tienen actividad de AL, puede tener implicaciones patogénicas en la trombofílía del SAF.