Anti-beta 2-glycoprotein I, antiprothrombin antibodies, and the risk of thrombosis in the antiphospholipid syndrome

Immune thrombocytopenia in patients with connective tissue disorders and the antiphospholipid antibody syndrome

It has been theorized that immune thrombocytopenia (ITP) is a syndrome characterized by various defects in immune regulation, resulting in a common phenotype, decreased blood platelets, and symptoms of mucocutaneous bleeding. Most often, successful treatment of the underlying connective tissue disorder with corticosteroids or other disease-modifying agents can simultaneously improve concurrent thrombocytopenia. The best evidence to date would support the targeting of treatment to the connective tissue disorder, expecting a simultaneous improvement in the platelet count. Due to the frequent relapses associated with many of the connective tissue disorders and the frequent use of immunosuppressant agents, splenectomy should be undertaken only in highly refractory patients. Differentiating the varying immunopathic etiologies that contribute to development of connective tissue disorders may lead to a better understanding of the mechanisms of thrombocytopenia in a subset of these patients. The use of target therapies to treat connective tissue disorders has the potential of reducing the risk of the development of ITP or, conversely, inducing the development of immune thrombocytopenia.

Clinical course of high-risk patients diagnosed with antiphospholipid syndrome

BACKGROUND

The characteristics and the clinical course of antiphospholipid syndrome (APS) in high-risk patients that are positive for all three recommended tests that detect the presence of antiphospholipid (aPL) antibodies have not been described.

METHODS

This retrospective analysis of prospectively collected data examined patients referred to Italian Thrombosis Centers that were diagnosed with definite APS and tested positive for aPL [lupus anticoagulant (LA), anti-cardiolipin (aCL), and anti-beta2-glycoprotein I (beta2GPI) antibodies]. Laboratory data were confirmed in a central reference laboratory.

RESULTS

One hundred and sixty patients were enrolled in this cohort study. The qualifying events at diagnosis were venous thromboembolism (76 cases; 47.5%), arterial thromboembolism (69 cases; 43.1%) and pregnancy morbidity (11 cases; 9.7%). The remaining four patients (2.5%) suffered from catastrophic APS. The cumulative incidence of thromboembolic events in the follow-up period was 12.2% (95% CI, 9.6-14.8) after 1 year, 26.1% (95% CI, 22.3-29.9) after 5 years and 44.2% (95% CI, 38.6-49.8) after 10 years. This was significantly higher in those patients not taking oral anticoagulants as compared with those on treatment (HR=2.4 95% CI 1.3-4.1; P<0.003). Major bleeding associated with oral anticoagulant therapy was low (0.8% patient/years). Ten patients died (seven were cardiovascular deaths).

CONCLUSIONS

Patients with APS and triple positivity for aPL are at high risk of developing future thromboembolic events. Recurrence remains frequent despite the use of oral anticoagulants, which significantly reduces the risk of thromboembolism.

[Val247Leu polymorphism of beta2 glycoprotein 1 gene may justify the genesis of anti beta2GP1 antibodies and antiphospholipid syndrome in multibacillary leprosy]

BACKGROUND - Multibacillary (MB) leprosy may be manifested with antiphospholipid antibodies (aPL), among which anti-beta2GP1 (beta2-glycoprotein 1). High titers of aPL are associated with APS (Antiphospholipid Syndrome), characterized by thrombosis. The mutation Val247Leu in the domain V of beta2GP1 exposes hidden epitopes with consequent development of anti-beta2GP1 antibodies.

OBJECTIVE

To evaluate the Val247Leu polymorphism of beta2GP1 gene and its correlation with anti-beta2GP1 antibodies in leprosy patients.

METHODS

The Val247Leu polymorphism was performed by PCR-RFLP and anti-beta2GP1 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-beta2GP1 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-beta2GP1 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 beta2GP1 and development of anti-beta2GP1 antibodies, with consequent thrombosis and APS.

The association of antiphospholipid antibodies with pregnancy-related first time venous thrombosis--a population-based case-control study

In this population-based case-control study we explored the association of antiphospholipid antibodies with pregnancy-related venous thrombosis. From 1990 through 2003 615 pregnant women were identified at 18 hospitals in Norway with a diagnosis of first time VT. In 2006, 531 of 559 eligible cases and 1092 of 1229 eligible controls were invited for further investigations. The final study population comprised 313 cases and 353 controls, who completed a comprehensive questionnaire and donated a single blood sample, 3-16 years after index pregnancy. We report the results on lupus anticoagulant, anticardiolipin antibodies, and anti-ss(2) glycoprotein-1 antibodies alone, in combination, and with the contribution of the factor V Leiden and the prothrombin gene G20210A polymorphisms. Cut-off values for APAs were chosen according to current international consensus. 29 (9.3%) of the cases and 24 (6.8%) of the controls had at least one positive test for APAs (OR 1.4; 95% CI 0.8-2.5). Nine cases (2.8%) and no controls had more than one positive test (multi-positivity) for APAs. After excluding women with factor V Leiden or prothrombin polymorphisms, still 6 cases were multi-positive for APAs. We conclude that multi-positivity, but not single-positivity, for APAs was weakly associated with a history of ante- and postnatal VT.

Hydroxychloroquine protects the annexin A5 anticoagulant shield from disruption by antiphospholipid antibodies: evidence for a novel effect for an old antimalarial drug

Annexin A5 (AnxA5) is a potent anticoagulant protein that crystallizes over phospholipid bilayers (PLBs), blocking their availability for coagulation reactions. Antiphospholipid antibodies disrupt AnxA5 binding, thereby accelerating coagulation reactions. This disruption may contribute to thrombosis and miscarriages in the antiphospholipid syndrome (APS). We investigated whether the antimalarial drug, hydroxychloroquine (HCQ), might affect this prothrombotic mechanism. Binding of AnxA5 to PLBs was measured with labeled AnxA5 and also imaged with atomic force microscopy. Immunoglobulin G levels, AnxA5, and plasma coagulation times were measured on cultured human umbilical vein endothelial cells and a syncytialized trophoblast cell line. AnxA5 anticoagulant activities of APS patient plasmas were also determined. HCQ reversed the effect of antiphospholipid antibodies on AnxA5 and restored AnxA5 binding to PLBs, an effect corroborated by atomic force microscopy. Similar reversals of antiphospholipid-induced abnormalities were measured on the surfaces of human umbilical vein endothelial cells and syncytialized trophoblast cell lines, wherein HCQ reduced the binding of antiphospholipid antibodies, increased cell-surface AnxA5 concentrations, and prolonged plasma coagulation to control levels. In addition, HCQ increased the AnxA5 anticoagulant activities of APS patient plasmas. In conclusion, HCQ reversed antiphospholipid-mediated disruptions of AnxA5 on PLBs and cultured cells, and in APS patient plasmas. These results support the concept of novel therapeutic approaches that address specific APS disease mechanisms.

The geoepidemiology of the antiphospholipid antibody syndrome

Antiphospholipid antibodies (aPL) can be detected by functional (lupus anticoagulant) and/or by solid phase assays (anti-cardiolipin and anti-beta2 glycoprotein I). Although detectable in 1-5% of asymptomatic apparently healthy subjects, persistent aPL are significantly associated with recurrent arterial/venous thrombosis and with pregnancy morbidity. Such an association is the formal classification tool for the antiphospholipid syndrome (APS). The prevalence of the syndrome with no associated systemic connective tissue diseases (primary APS) in the general population is still a matter of debate since there are no sound epidemiological studies in the literature so far. aPL display higher prevalence in systemic lupus erythematosus and rheumatoid arthritis than in other systemic autoimmune diseases. However not all the aPL positive lupus patients display the clinical manifestations. Comparable findings may be found in the paediatric population, although anti-beta2 glycoprotein I antibodies are detected in healthy children more frequently than in adults. High prevalence of aPL has been also reported in clinical manifestations that are not formal APS classification criteria: heart valve disease, livedo reticular, nephropathy, neurological manifestations, and thrombocytopenia. Antiphospholipid antibodies can be associated with infectious processes, active vaccination, drug administration and malignancies. Their prevalence and titres are lower and the relationship with the APS clinical manifestations are less strong than in the previously mentioned conditions. Ethnicity was also reported to influence the prevalence of aPL.

Antiphospholipid syndrome review

The antiphospholipid syndrome (APS) is an autoimmune disorder presenting with tissue injury in various organs attributed to large or small vessel thrombosis or, in some instances, possible nonthrombotic inflammatory mechanisms, associated with in vitro evidence of antibodies to certain proteins, or proteinphospholipid complexes. Although the pathophysiology, diagnosis, and management of APS may seem clear and straightforward from a distance, closer inspection reveals a more complex, incomplete, and uncertain image. This article reviews the evolution of APS from the first description of lupus anticoagulant to the current criteria used to guide clinical research, critiques laboratory methods used to identify autoantibodies, comments on prognosis and management, and summarizes insights into the pathophysiology of this elusive disorder.

The association between circulating antibodies against domain I of beta2-glycoprotein I and thrombosis: an international multicenter study

BACKGROUND

Diagnosis of the antiphospholipid syndrome (APS) is difficult as a result of limited specificity of existing assays for detecting clinically relevant antiphospholipid antibodies. Anti-beta2-glycoprotein I (beta 2GPI) antibodies play a central role in the disease process of APS.

OBJECTIVES

We have investigated the relation between antiphospholipid antibodies with specificity for domain I of beta 2GPI and thrombosis/pregnancy morbidity in an international multicenter study.

PATIENTS/METHODS

Four hundred and seventy-seven patients derived from nine different centres met the inclusion criterion of having anti-beta 2GPI antibodies in their plasma/serum. Clinical data and results of tests for lupus anticoagulant, anti-cardiolipin antibodies and anti-beta 2GPI antibodies were established at the different centres of inclusion. After being re-tested for the presence of IgG and/or IgM anti-beta 2GPI antibodies, the samples were tested for the presence of IgG-directed against domain I of beta 2GPI and results were correlated with the thrombotic and obstetric history.

RESULTS

Re-testing for the presence of anti-beta 2GPI antibodies resulted in inclusion of 442/477 patients. IgG class anti-domain I antibodies were present in plasma of 243/442 patients (55%). 201/243 (83%) had a history of thrombosis. This resulted in an odds ratio of 3.5 (2.3-5.4, 95% confidence interval) for thrombosis. Anti-domain I IgG antibodies were also significantly correlated with obstetric complications [odds ratio: 2.4 (1.4-4.3, 95% confidence interval)].

CONCLUSION

In this multicenter study, the detection of IgG antibodies that are directed against domain I of beta 2GPI proved to be more strongly associated with thrombosis and obstetric complications than those detected using the standard anti-beta 2GPI antibody assay.

Prevalence and clinical correlates of anti‐phospholipid antibodies in South Africans with systemic lupus erythematosus

OBJECTIVE

To determine the prevalence and clinical correlates of anti-phospholipid antibodies (aPL), including anti-cardiolipin antibodies (aCL), lupus anti-coagulant (LA), anti-beta2-glycoprotein 1 (abeta2GP1), and anti-prothrombin (aPT) antibodies, in Black South African patients with systemic lupus erythematosus (SLE).

METHODS

A cross-sectional study of 100 SLE patients in whom clinical characteristics, including features of the anti-phospholipid syndrome (APS), disease activity, and damage were documented, and sera tested for aCL, abeta2GP, and aPT of all isotypes, and LA.

RESULTS

Positive aCL, abeta2GPI, aPT, and LA were found in 53, 84, 20, and 2 patients, respectively. Immunoglobulin (Ig)A aCL and IgG abeta2GPI were the commonest aCL (49.1%) and abeta2GPI (47%) isotypes, respectively. IgA abeta2GPI were associated with both a history of thrombosis alone (p<0.05) and a history of any clinical feature, thrombosis, and/or spontaneous abortion of the APS (p<0.05); IgA aCL were associated with a history of any clinical APS event (p<0.05); and abeta2GPI of any isotype were associated with a history of arthritis (p<0.001).

CONCLUSION

Our findings provide further evidence that screening for abeta2GPI and IgA aCL isotypes may improve the risk assessment for APS in SLE patients of African extraction. Further prospective studies are warranted to determine the clinical utility of these tests and to elucidate the genetic basis for the increased IgA aPL response in SLE patients of African extraction.

Therapeutic approaches to secondary immune thrombocytopenic purpura

Secondary thrombocytopenia is similar to primary or idiopathic thrombocytopenia (ITP) in that it is characterized by reduced platelet production or increased platelet destruction resulting in platelet levels<60,000/microL. Thrombocytopenia can occur from secondary causes associated with chronic disorders or with disturbed immune function due to chronic infections, lymphoproliferative and myeloproliferative disorders, pregnancy, or autoimmune disorders. Diagnosis of secondary ITP in some cases is complex, and the thrombocytopenia can often be resolved by treating the underlying disorder to the extent this is possible. In most cases, treatment is focused on reducing platelet destruction, but, in some cases, treatment may also be directed at stimulating platelet production. The most problematic cases of thrombocytopenia may be seen in pregnant women. This review will address various agents and their utility in treating ITP from secondary causes; in addition, thrombocytopenia in pregnancy, ITP in immunodeficiency conditions, and drug-induced thrombocytopenia will be discussed. Unlike primary ITP, treatment often must be tailored to the specific circumstance underlying the secondary ITP, even if the condition itself is incurable.

Anti-beta(2)-glycoprotein-I and anti-phosphatidylserine antibodies in women with spontaneous pregnancy loss

OBJECTIVE

To evaluate the role of anti-beta(2)-glycoprotein-I (anti-beta(2)GPI-ab) and anti-phosphatidylserine (aPS-ab) antibodies as a risk factor in both recurrent miscarriage (RM) and unexplained fetal losses (UFL).

DESIGN

Retrospective, cohort study.

SETTING

Vall d'Hebron University Hospital, Barcelona, Spain.

PATIENT(S)

122 pregnant women divided in two groups: study group of 54 women with RM and/or UFL and control group of 68 pregnant without RM history.

INTERVENTION(S)

Analysis of lupus anticoagulant, anticardiolipin antibodies, and anti-beta(2)GP1 and aPS antibodies.

MAIN OUTCOME MEASURE(S)

Comparison of aPL antibody between groups.

RESULT(S)

The prevalence of aPL positive results was 8 out of 54 (14.8%) in the study group and 3 out of 68 (4.41%) in the controls. In the RM subgroup, the prevalence was 3 out of 25 (12%) versus 3 out of 68 (4.4%), and 7 out of 34 (20.6%) versus 3 out of 68 (4.4%) in UFL subgroup. As a whole, the prevalence of anti-beta(2)GP1-ab in the RM/UFL group showed a difference compared with controls but not aPS-ab. In the RM women, anti-beta(2)GP1-ab was positive in 3 out of 25 (12%) versus 1 out of 68 (1.5%) in controls and in 4 out of 34 versus 0 out of 68 cases in women with UFL. In the RM subgroup, aPS-ab was positive in 1 out of 25 (4%) versus 2 out of 68 (2.9%) in control group and in 3 out of 34 versus 2 out of 68 cases in women with UFL.

CONCLUSION(S)

Our results suggest that anti-beta(2)GP1-ab but not aPS-ab is related to RM/UFL and should be considered as a pregnancy-loss risk factor.

Laboratory Evaluation of Antiphospholipid Antibodies in Patients With Venous Thromboembolism

The objective of our study was to evaluate the significance of extended antiphospholipid profile in patients with venous thromboembolism without any systemic autoimmune disease. In 140 patients (age 18-69 years; 47.1% men) with venous thromboembolism and 136 control participants we tested anticardiolipin antibodies, anti-beta 2 glycoprotein I (anti-β2-GPI) and also non-criteria antiphospholipid antibodies: antiphosphatidic acid, antiphosphatidylethanolamine, antiphosphatidylglycerol, antiphosphatidylinositol, antiphosphatidylserine. Commercial and in-house enzyme-linked immunosorbent assays were used. The antibodies with significantly higher prevalence in patients (compared to controls) were: immunoglobulin (Ig) M-anticardiolipin antibodies (12.9%; P = 0.035), IgG-anti-β2-GPI (16.4%; P = 0.0032), IgM-antiphosphatidylethanolamine (14.3%; P = 0.014). In most cases, these three antibodies did not overlap. In conclusion, of non-criteria antiphospholipid antibodies, only antiphosphatidylethanolamine were significantly more prevalent in patients with venous thromboembolism, with only minor overlapping with the criteria antiphospholipid antibodies. Our results suggest the possible utility of searching for antiphosphatidylethanolamine in the clinical suspicion of antiphospholipid syndrome and the absence of criteria antiphospholipid antibodies.

Annexin A2: biology and relevance to the antiphospholipid syndrome

Antiphospholipid antibodies (aPL), the majority of which are directed against beta(2)-glycoprotein I (beta(2)GPI), are associated with an increased incidence of venous and arterial thrombosis. The pathogenesis of antiphospholipid/anti-beta(2)GPI-associated thrombosis has not been defined, and is likely multifactorial. However, accumulating evidence suggests an important role for endothelial cell activation with the acquisition of a procoagulant phenotype by the activated endothelial cell. Previous work demonstrated that endothelial activation by antiphospholipid/anti-beta(2)GPI antibodies is beta(2)GPI-dependent. We extended these observations by defining annexin A2 as an endothelial beta(2)GPI binding site. We also observed that annexin A2 plays a critical role in endothelial cell activation induced by anti-beta(2)GPI antibodies, and others have described direct endothelial activation by anti-annexin A2 antibodies in patients with aPL . Similar findings have been reported using human monocytes, which also express annexin A2. Because annexin A2 is not a transmembrane protein, how binding of beta(2)GPI/anti-beta(2)GPI antibodies, or anti-annexin A2 antibodies, to endothelial annexin A2 causes cellular activation is unknown. Recent studies, however, suggest an important role for the Toll-like receptor family, particularly TLR4. In this article, we review the role of these interactions in the activation of endothelial cells by aPL . The influence of these antibodies on the ability of annexin A2 to enhance t-PA-mediated plasminogen activation is also discussed.

How we diagnose the antiphospholipid syndrome

The antiphospholipid syndrome (APS) is an acquired thrombophilia, characterized by the occurrence of venous and arterial events. This article examines the laboratory and key clinical aspects of APS. Particular focus is given to anti–beta 2-glycoprotein I (β2GPI) antibodies in view of their recent inclusion in the APS classification criteria. The clinical utility of using the β2GPI enzyme-linked immunosorbent assay, in conjunction with the established lupus anticoagulant assays and cardiolipin enzyme-linked immunosorbent assay, for diagnosing and risk stratifying patients suspected of having APS is discussed. The relative importance of the various assays in diagnosing obstetric APS (early and late gestation miscarriages) is explored. The implications of recent epidemiologic findings for possibly understanding the underlying pathophysiologic mechanisms of obstetric APS are highlighted. Insights into which patients with obstetric APS may be at most risk of thrombotic complications are presented.

Antiphospholipid antibodies: paradigm in transition

OBJECTIVES

This is a critical review of anti-phospholipid antibodies (aPL). Most prior reviews focus on the aPL syndrome (APS), a thrombotic condition often marked by neurological disturbance. We bring to attention recent evidence that aPL may be equally relevant to non-thrombotic autoimmune conditions, notably, multiple sclerosis and ITP.

ORGANIZATION

After a brief history, the recent proliferation of aPL target antigens is reviewed. The implication is that many more exist. Theories of aPL in thrombosis are then reviewed, concluding that all have merit but that aPL may have more diverse pathological consequences than now recognized. Next, conflicting results are explained by methodological differences. The lupus anticoagulant (LA) is then discussed. LA is the best predictor of thrombosis, but why this is true is not settled. Finally, aPL in non-thrombotic disorders is reviewed.

CONCLUSION

The current paradigm of aPL holds that they are important in thrombosis, but they may have much wider clinical significance, possibly of special interest in neurology.

Diagnosis of antiphospholipid syndrome

Antiphospholipid syndrome is a multisystem autoimmune disease, characterized by recurrent vascular thrombosis and/or pregnancy losses in the presence of persistently positive antiphospholipid antibodies. In clinical practice, testing for anticardiolipin antibodies and lupus anticoagulant is mandatory for the laboratory diagnosis of antiphospholipid syndrome. Identification of patients with antiphospholipid syndrome is important, as prophylactic anticoagulant therapy may prevent thrombosis from recurring, and treatment during pregnancy can improve fetal and maternal outcome.

IgA antiphospholipid antibodies are an independent risk factor for thromboses

Antiphospholipid antibodies (lupus anticoagulant, anti-cardiolipin and anti-β2-glycoprotein I antibodies, mostly IgG isotype) are strong risk factors for thrombosis. Because a paucity of information on IgA isotype exists in the literature, we retrospectively evaluated the thrombotic significance of IgA antiphospholipid antibodies. We included 472 patients with clinical information on thrombotic events and complete laboratory work-up for antiphospholipid antibodies syndrome. Odds ratios (OR) of various antiphospholipid antibodies for thrombosis were calculated by univariate and multivariate analyses. Lupus anticoagulant alone was detected in 57 (12%) patients, ELISA-based antibodies (IgG, IgM, IgA) against cardiolipin, phosphatidylserine or β2-glycoprotein-I alone were detected in 131 (28%) patients, whereas 80 (17%) patients had both. Antibody isotype distribution was IgG 32%, IgM 60% and IgA 56%. Univariate analysis showed a statistically significant risk of thrombosis in patients with elevated titres of IgA of any ELISA-based antiphospholipid antibodies (OR 1.77). Stepwise logistic regression (multivariate) analysis identified elevated titres of any ELISA-based IgA antiphospholipid antibodies as an independent risk factor for thrombosis (OR 1.6) in the entire cohort, and in the subgroup of patients without concurrent presence of lupus anticoagulant (OR 1.8). IgA antiphospholipid antibodies appear to be a significant independent risk factor for thrombosis, thereby meriting evaluation in patients with unexpected thrombosis.

Tissue factor in antiphospholipid antibody-induced pregnancy loss: a pro-inflammatory molecule

Fetal loss in patients with antiphospholipid antibodies (aPL) has been ascribed to thrombosis of placental vessels. However, we have shown that inflammation, specifically complement activation with generation of the anaphylotoxin C5a, is an essential mediator of fetal injury. We have analysed the role of tissue factor (TF) in a mouse model of aPL-induced pregnancy loss. TF is the major cellular activator of the coagulation cascade but also has cell signaling activity. Mice that received aPL-IgG showed strong TF staining throughout the decidua and on embryonic debris. This TF staining was not associated with either fibrin staining or thrombi in deciduas. The absence of fibrin deposition and thrombi suggests that TF-dependent activation of coagulation does not mediate aPL-induced pregnancy loss.We found that either blockade of TF with a monoclonal antibody in wild type mice or a genetic reduction of TF prevented aPL-induced inflammation and pregnancy loss indicated a pathogenic role for TF in aPL-induced pregnancy complications. In response to aPL-generated C5a, neutrophils express TF potentiating inflammation in the deciduas and leading to miscarriages. Importantly, we showed that TF in myeloid cells, but not fetal-derived cells (trophoblasts), was associated with fetal injury, suggesting that the site for pathologic TF expression is neutrophils. We found that TF expression in neutrophils contributes to respiratory burst and subsequent trophoblast injury and pregnancy loss induced by aPL. The identification of TF, acting as an important pro-inflammatory mediator in aPL-induced fetal injury, provides a new target for therapy to prevent pregnancy loss in the aPL syndrome.

Predictive, protective, orphan autoantibodies: the example of anti-phospholipid antibodies

Anti-phospholipid antibodies (aPL) are one of the most recent examples of autoantibodies that can appear even long time before any clinical manifestation can be associated with them. There is a general agreement that they may represent a strong risk factor for recurrent thrombosis and/or fetal losses. Anti-phospholipid antibodies represent a necessary but not sufficient factor (first hit) for thrombosis, and require additional triggering factors (second hit) to disclose the thrombogenic activity. Several factors may affect the predictive value of aPL, including titre, immunoglobulin isotype, fine antigenic specificity and affinity binding activity. Their careful evaluation is suggested in order to characterize the true predictive value of aPL.

Antiphospholipid antibodies: laboratory and pathogenetic aspects

Antiphospholipid antibodies (aPL) constitute a heterogeneous group of autoantibodies that share the ability to bind phospholipids (PL) alone, protein-PL complexes, or PL-binding proteins. They have been detected in isolation, in association with autoimmune diseases such as systemic lupus erythematosus (SLE), and during the course of different infections. aPL have been associated with an array of clinical manifestations in virtually every organ, although deep vein and arterial thrombosis as well as pregnancy morbidity are predominant. The co-occurrence of these clinical findings with aPL constitutes the so-called antiphospholipid syndrome (APS). aPL can be detected by immunological methods [e.g., anticardiolipin antibodies (aCL)] or by functional methods that exploit the effect of aPL on blood coagulation [lupus anticoagulant (LA)]. Since aPL are heterogeneous, numerous immunological and coagulation assays have been developed. These assays have not been fully standardized, and, therefore, problems such as high interlaboratory variation are relatively frequent. Recently, recommendations have been published regarding LA and aCL testing. Not all aPL are pathogenic. However, when they are not associated with infections, they have a role in the pathogenesis of APS. Clinical and experimental data have shown that aPL exert their pathogenic activity by interfering with the function of coagulation factors, such as thrombin and factors X, XI and XII, and with the function of anticoagulant proteins of the protein C system. In addition, aPL interaction with platelets and endothelial cells induces a pro-adhesive activated phenotype.

Lupus nephritis and Raynaud's phenomenon are significant risk factors for vascular thrombosis in SLE patients with positive antiphospholipid antibodies

This study is aimed to determine the predictors of nongravid vascular thrombosis in systemic lupus erythematosus (SLE) patients with positive antiphospholipid antibodies (SLE-aPL). A cohort of 67 SLE-aPL patients who had at least one positive test for lupus anticoagulant (LA), anticardiolipin (aCL), or anti-beta2glycoprotein-1(B2) was examined. Main outcome was the presence of vascular thrombosis. Association between thrombosis and risk factors was examined by contingency table. The odds ratio (OR) of significant predictors was determined by logistic regression. Three percent of patients were LA(+), 6% were aCL(+), 31% were B2(+), 3% were aCL(+)LA(+), 35.8% were aCL(+)B2(+), 7.5% were LA(+)B2(+), and 13.4% were positive for all tests. As for clinical manifestations, 79% had lymphopenia, 76% had lupus nephritis (LN), 41.8% had autoimmune hemolytic anemia, 34.3% had thrombocytopenia, 20.9% had abortion, and 19.4% had Raynaud's phenomenon (RP). Thrombosis occurred in 26 patients. The prevalence of thrombosis for SLE-aPL was 38.8%. Thrombosis was observed more frequently in patients with LA(+) (12 of 18) than the others (14 of 49; p = 0.01). Two-by-two table showed that oral contraceptive and LN were significantly associated with increased risk of thrombosis, while lymphopenia and antimalarials were significantly associated with decreased risk of thrombosis. Multivariate analysis confirmed that LN and RP were associated with increased risk of thrombosis (OR = 6.2 and 3.2; p = 0.005 and 0.008), while lymphopenia and antimalarials were associated with decreased risk of thrombosis (OR = 0.86 and 0.18; p = 0.02 and 0.034). LA is the strongest test to determine the risk of thrombosis in SLE-aPL. The presence of LN and RP strongly predicts thrombosis, while lymphopenia and antimalarials are protective. These findings help to identify patients who may benefit from prophylactic therapy.

Mechanisms of disease: antiphospholipid antibodies-from clinical association to pathologic mechanism

The discovery that antiphospholipid antibodies recognize plasma proteins that bind to phospholipids rather than recognizing phospholipids themselves has been a major advance in research into antiphospholipid syndrome (APS). It is now established that beta2-glycoprotein I (beta2 GPI) is the most important antigen for antiphospholipid antibodies. However, the possible pathologic mechanism is still much debated. This is mainly because not all patients with anti-beta2 GPI antibodies show clinical symptoms that are related to APS. Several reports indicate that anti-beta2 GPI antibodies with lupus anticoagulant (LA) activity are clinically of much importance. Most patients with LA caused by anti-beta2 GPI antibodies suffer from thrombosis as a result of recognition of the first domain of beta2 GPI by these antibodies. In the search for a pathologic mechanism that might explain the high occurrence of thrombosis in patients with anti-domain I antibodies (LA-causing anti-beta2 GPI antibodies), it was found that these antibodies show increased resistance to the anticoagulant activity of annexin A5. We have shown that the same population of antibodies also displays increased resistance to activated protein C. Owing to the diversity of clinical symptoms related to APS, it is likely that other pathologic mechanisms also contribute to the occurrence of APS-related symptoms.

The obstetric antiphospholipid syndrome

The association of persistent presence of circulating antiphospholipid antibodies and thromboembolic events, (recurrent) pregnancy loss or both is termed antiphospholipid syndrome. Pregnancies in women with the syndrome should be regarded as at high-risk for complications. Optimal management consisting of close follow-up and pharmacological treatment can result in about 70-80% live births. Apart from the laboratory diagnosis of the syndrome and pathophysiology, this review will focus on treatment during pregnancy.

Anti-beta 2 glycoprotein I antibodies and the risk of myocardial infarction in young premenopausal women

BACKGROUND

Contrasting data have been reported on the association between the presence of anti-phospholipid antibodies (aPL) and arterial thrombotic events, particularly those in coronary arteries. This discrepancy is perhaps related to the confounding effect of traditional risk factors. Among them, coronary atherosclerosis appears to be the most important in studies conducted in middle-aged and elderly patients.

OBJECTIVE

To minimize such confounding effects, a multicenter case-control study on the association between aPL and myocardial infarction (MI) was carried out in a rare cohort of young premenopausal women.

METHODS

We evaluated 172 cases hospitalized for a first MI before the age of 45 years and 172 controls individually matched with cases for age, sex and geographical origin. Clinical and laboratory data were collected and levels of anti-cardiolipin (aCL), anti-beta2 glycoprotein I (anti-beta2GPI) and anti-nuclear antibodies (ANA) were measured.

RESULTS

A significant association between MI and IgG/IgM anti-beta2GPI antibodies was observed; the results were confirmed after adjusting for smoking and hypertension (anti-beta2GPI IgG OR = 2.47, 95% CI 1.81-3.38; anti-beta2GPI IgM 4th quartile OR 3.68, 95% CI 1.69-8.02). The association between anti-beta2GPI antibodies and MI was detected in both subgroups with and without coronary artery stenosis. Whereas the association of aCL IgG with MI was modest, ANA showed no significant association with MI. No aPL were found in unselected patients (mainly males) who recently developed acute MI.

CONCLUSIONS

Anti-beta2GPI antibodies are a significant risk factor for MI in young premenopausal women independently of other risk factors, including the degree of coronary artery stenosis.

The Role of Anti-Phospholipid Auto Antibodies Syndrome in Cerebrovascular Diseases

Objectives: The aims of the study are to determine the role of anti-phospholipid autoantibodies (APLAs) among patients with stroke and/or transient ischaemic attacks (TIAs), to identify the types and effective isotype of some important APLAs which are lupus anticoagulant (LA), anticardiolipin (aCL), anti∼fi2 glycoprotein I dependent (afi2-GPI), and anti-phosphatidyl serine (aPS). Also, to find out any concomitant effect of non-APLAparameters not specific to antiphospholipid syndrome (APS).

Subjects and Methods: This study was carried out on 50 patients attending mainly the Teaching and General Hospitals in Mosul, Duhok, and Erbil Cities, Iraq during the period between 1st March 2004 and 1st March 2005. The studied cases were under 50 years of age, and had no recognizable risk factors. The activated partial thromboplastin time (APTT) was used for LA estimation and ELISA assay was used to test for IgG& IgM isotypes ofaCL, aJ32-GPI, and aPS. The ANA, RF, VDRL, CRP, and C4 complement were tested by different immuoserological methods. The thrombocytopenic (TP) status was diagnosed by estimation of platelets counts.

Results: The strokes and!or TIAs related to APS were diagnosed in 22/50 (44%) of patients and a significant correlation was reported among patients with IgG plus IgM aCL (p <  0.05), IgG afi2-GPI (p <  0.05), and IgG aPS (p <  0.05). In APLAs positive patients, raised CRP concentrations were reported in 36.4%, TP status in 22.7%, ANA in 22.7%, RF positive in 13.6%, and low C4 levels in l3.6%. Finally,the FP-VDRL test was found in 50 % of APLAs positive cases.

Conclusions: The aCL, afi2- GPI, and aPS antibodies were shown to play a significant role in the development of stroke and!or TIAs among the studied cases.