A phospholipid-beta 2-glycoprotein I complex is an antigen for anticardiolipin antibodies occurring in autoimmune disease but not with infection

Thrombosis and Hyperinflammation in COVID-19 Acute Phase Are Related to Anti-Phosphatidylserine and Anti-Phosphatidylinositol Antibody Positivity

Antiphospholipid antibodies (APLA) are strongly associated with thrombosis seen in patients with antiphospholipid syndrome. In COVID-19, thrombosis has been observed as one of the main comorbidities. In patients hospitalised for COVID-19, we want to check whether APLA positivity is associated with COVID-19-related thrombosis, inflammation, severity of disease, or long COVID-19. We enrolled 92 hospitalised patients with COVID-19 between March and April 2020 who were tested for 18 different APLAs (IgG and IgM) with a single line-immunoassay test. A total of 30 healthy blood donors were used to set the cut-off for each APLA positivity. Of the 92 COVID-19 inpatients, 30 (32.61%; 95% CI [23.41-43.29]) tested positive for APLA, of whom 10 (33.3%; 95% CI [17.94-52.86]) had more than one APLA positivity. Anti-phosphatidylserine IgM positivity was described in 5.4% of inpatients (n = 5) and was associated with the occurrence of COVID-19-related thrombosis (p = 0.046). Anti-cardiolipin IgM positivity was the most prevalent among the inpatients (n = 12, 13.0%) and was associated with a recorded thrombosis in their clinical history (p = 0.044); however, its positivity was not associated with the occurrence of thrombosis during their hospitalisation for COVID-19. Anti-phosphatidylinositol IgM positivity, with a prevalence of 5.4% (n = 5), was associated with higher levels of interleukin (IL)-6 (p = 0.007) and ferritin (p = 0.034). Neither of these APLA positivities was a risk factor for COVID-19 severity or a predictive marker for long COVID-19. In conclusion, almost a third of COVID-19 inpatients tested positive for at least one APLA. Anti-phosphatidylserine positivity in IgM class was associated with thrombosis, and anti-phosphatidylinositol positivity in IgM class was associated with inflammation, as noticed by elevated levels of IL-6. Thus, testing for non-criteria APLA to assess the risk of clinical complications in hospitalised COVID-19 patients might be beneficial. However, they were not related to disease severity or long COVID-19.

Indication and outcome of lupus anticoagulant and antiphospholipid antibodies testing in routine clinical practice

OBJECTIVES

Lupus anticoagulans (LACs) and aPLs, both further summarized as aPL, are frequently assessed in routine daily clinical practice in diagnostic workups for suspected autoimmune diseases or to test for underlying risk factors in patients with thrombosis or obstetric complications. The aim of this study was to determine the prevalence of aPL positivity in patients with an indication for aPL testing in routine clinical practice.

METHODS

In this retrospective single-centre study, indication for aPL testing, aPL test results and clinical data were collected for patients tested between June 2015 and April 2018.

RESULTS

During the study period, 16 847 single aPL tests were performed in 2139 patients. In 212 patients one or more positive aPL test was found, confirmed in 43.9% with a second positive test. Indications for aPL testing were diagnostic workup/follow-up of autoimmune diseases (33.6%), thrombosis (21.4%) and obstetric complications (28%). Seventy-four patients (3.5% of all patients) fulfilled the criteria of APS, of whom 51% were newly diagnosed. Second positive aPL titres and titres of APS patients were significantly higher compared with positive aPL titres at the first measurement (P < 0.05). Patients with indications of arterial thrombosis and diagnostic workup/follow-up of autoimmune diseases had significantly higher levels of aCL IgG and anti-β2 glycoprotein I (β2GPI) IgG compared with patients with other indications.

CONCLUSION

The prevalence of one or more positive aPL test was 9.9% and APS was diagnosed in 3.5% of the patients. Patients with arterial thrombosis had significantly higher anti-β2GPI IgG and aCL IgG, which should be confirmed in future studies.

Prothrombotic autoantibodies in serum from patients hospitalized with COVID-19

Patients with COVID-19 are at high risk for thrombotic arterial and venous occlusions. Lung histopathology often reveals fibrin-based blockages in the small blood vessels of patients who succumb to the disease. Antiphospholipid syndrome is an acquired and potentially life-threatening thrombophilia in which patients develop pathogenic autoantibodies targeting phospholipids and phospholipid-binding proteins (aPL antibodies). Case series have recently detected aPL antibodies in patients with COVID-19. Here, we measured eight types of aPL antibodies in serum samples from 172 patients hospitalized with COVID-19. These aPL antibodies included anticardiolipin IgG, IgM, and IgA; anti-β2 glycoprotein I IgG, IgM, and IgA; and anti-phosphatidylserine/prothrombin (aPS/PT) IgG and IgM. We detected aPS/PT IgG in 24% of serum samples, anticardiolipin IgM in 23% of samples, and aPS/PT IgM in 18% of samples. Antiphospholipid autoantibodies were present in 52% of serum samples using the manufacturer's threshold and in 30% using a more stringent cutoff (≥40 ELISA-specific units). Higher titers of aPL antibodies were associated with neutrophil hyperactivity, including the release of neutrophil extracellular traps (NETs), higher platelet counts, more severe respiratory disease, and lower clinical estimated glomerular filtration rate. Similar to IgG from patients with antiphospholipid syndrome, IgG fractions isolated from patients with COVID-19 promoted NET release from neutrophils isolated from healthy individuals. Furthermore, injection of IgG purified from COVID-19 patient serum into mice accelerated venous thrombosis in two mouse models. These findings suggest that half of patients hospitalized with COVID-19 become at least transiently positive for aPL antibodies and that these autoantibodies are potentially pathogenic.

Prothrombotic antiphospholipid antibodies in COVID-19

Patients with coronavirus disease 19 (COVID-19) are at high risk for thrombotic arterial and venous occlusions. At the same time, lung histopathology often reveals fibrin-based occlusion in the small vessels of patients who succumb to the disease. Antiphospholipid syndrome (APS) is an acquired and potentially life-threatening thrombophilia in which patients develop pathogenic autoantibodies (aPL) targeting phospholipids and phospholipid-binding proteins. Case series have recently detected aPL in patients with COVID-19. Here, we measured eight types of aPL [anticardiolipin IgG/IgM/IgA, anti-beta-2 glycoprotein I IgG/IgM/IgA, and anti- phosphatidylserine/prothrombin (aPS/PT) IgG/IgM] in the sera of 172 patients hospitalized with COVID-19. We detected aPS/PT IgG in 24%, anticardiolipin IgM in 23%, and aPS/PT IgM in 18%. Any aPL was present in 52% of patients using the manufacturer's threshold and in 30% using a more stringent cutoff (≥40 units). Higher levels of aPL were associated with neutrophil hyperactivity (including the release of neutrophil extracellular traps/NETs), higher platelet count, more severe respiratory disease, and lower glomerular filtration rate. Similar to patients with longstanding APS, IgG fractions isolated from patients with COVID-19 promoted NET release from control neutrophils. Furthermore, injection of these COVID-19 IgG fractions into mice accelerated venous thrombosis. Taken together, these studies suggest that a significant percentage of patients with COVID-19 become at least transiently positive for aPL and that these aPL are potentially pathogenic.

First-Line, Non-Criterial Antiphospholipid Antibody Testing for the Diagnosis of Antiphospholipid Syndrome in Clinical Practice: A Combination of Anti-β2 -Glycoprotein I Domain I and Anti-Phosphatidylserine/Prothrombin Complex Antibodies Tests

OBJECTIVE

To assess the value of a combination of anti-β₂ -glycoprotein I (anti-β₂ GPI) domain I antibody and anti-phosphatidylserine/prothrombin complex (anti-PS/PT) antibody tests for the diagnosis of antiphospholipid syndrome (APS).

METHODS

This cross-sectional study involved a cohort of the patients who visited our clinic from April 2005 to March 2013. Tests for anti-β₂ GPI domain I antibodies, IgG anti-PS/PT antibodies, and IgM anti-PS/PT antibodies, together with tests for criteria-defined antiphospholipid antibodies (aPL), were performed in all patients. The total antiphospholipid score (aPL-S) was calculated for each patient according to titers of and positivity for aPL.

RESULTS

The study enrolled 157 patients (51 patients with APS and 106 with non-APS autoimmune diseases). All 21 patients positive for both anti-β₂ GPI domain I antibodies and IgG and/or IgM (IgG/IgM) anti-PS/PT antibodies had APS with a high total aPL-S (median 46, range 26-76), as did all of the 10 patients who were positive for anti-β₂ GPI domain I antibodies but negative for IgG/IgM anti-PS/PT antibodies (median 22, range 4-39). Of the 14 patients who were positive for IgG/IgM anti-PS/PT antibodies but negative for anti-β₂ GPI domain I antibodies, 11 (79%) had APS; these individuals also had high total aPL-S values (median 23, range 11-60). In contrast, only 9 of the 112 patients (8%) with none of these antibodies had APS.

CONCLUSION

The combination of the IgG anti-β₂ GPI domain I antibody and IgG/IgM anti-PS/PT antibody tests shows a high positive predictive value for the diagnosis of APS and a strong correlation with the aPL-S. This combination as the first-line test for aPL may contribute to the simple and definite identification of APS with a high risk of thrombosis in clinical practice.

Reimagining the antiphospholipid syndrome, an enigmatic thrombophilic disorder, through the looking glass of microscopic imaging

The antiphospholipid syndrome (APS) is an autoimmune thrombophilic disorder that was described as a diagnostic entity over 30 years ago. And yet the pathogenic mechanisms that are responsible for its clinical manifestations remain to be definitively established. The syndrome is defined by (1) the concurrence of vascular thrombosis and/or pregnancy complications together with (2) positivity for immunoassays and coagulation tests that were derived from clinical observations of two anomalous laboratory test results-specifically, false positivity for syphilis infection in uninfected individuals and the finding of inhibitors of blood coagulation in patients who lacked any bleeding tendencies. Over the years, these were standardized into immunoassays and coagulation assays for APS. Here, we describe how prior knowledge of the immunologic and coagulation aspects of the disorder led to research involving a range of imaging modalities including light microscopy, immunohistochemistry, confocal scanning laser microscopy, transmission and scanning electron microscopy, and atomic force microscopy. In turn, the results from those studies led to a "reimagining" of APS that has advanced the understanding of pathogenic mechanisms of the disorder and has led to the development of novel mechanistically based diagnostics along with potential new treatment approaches that target disease mechanisms.

Anti-phospholipid Antibodies and Smoking: An Overview

Antiphospholipid syndrome is characterized by the presence of antiphospholipid antibodies, specifically lupus anticoagulant, anticardiolipin antibodies, and anti-β2 glycoprotein-I antibodies. Antiphospholipid syndrome can occur on its own or in association with other autoimmune diseases, most commonly systemic lupus erythematosus (SLE). A connection between cigarette smoking and anti-phospholipid antibodies (aPL) was first reported in the late1980s. Systemic lupus erythematosus patients with aPL are more likely to be smokers than those without aPL. These patients have a particularly high frequency of vascular events. Recently, a potential link between periodontitis, tobacco, and aPL has been proposed. Research has also suggested that periodontitis and Porphyromonas gingivalis infection are associated with citrullination through the action of peptidylarginine deiminase. A strong correlation between smoking and the presence of citrillunated autoantibodies, which are characteristic of rheumatoid arthritis, has also been observed. While many studies have investigated possible links between infection and aPL in patients with autoimmune diseases, the association of smoking with aPL has not been systematically examined. The fact that both aPL and tobacco are risk factors for thrombosis has complicated efforts to evaluate these factors separately. Also, there has been great variability in measurement techniques, and laboratories lack routine methods for differentiating transient and persistent aPL; both of these factors can make interpretation of autoantibody results quite challenging. This review summarizes the clinical evidence supporting a posited link between aPL and smoking, both in patients with a systemic autoimmune disease and in patients with other medical conditions.

Risk of developing antiphospholipid antibodies following viral infection: a systematic review and meta-analysis

Objective The objective of this paper is to conduct a systematic review and meta-analysis on the risk of developing elevated antiphospholipid (aPL) antibodies and related thromboembolic and/or pregnancy events following a viral infection. Method We searched Medline, EMBASE, Web of Science, PubMed ePubs, and Cochrane Central Register of Controlled Trials through June 2016. Independent observational studies of elevated aPL antibodies in patients with a viral infection compared with controls or patients with lupus were included. Results We analyzed 73 publications for 60 studies. Human immunodeficiency virus (HIV) and hepatitis C virus (HCV) were most commonly reported. Compared with healthy controls, patients with HIV were more likely to develop elevated anticardiolipin (aCL) antibodies (risk ratio (RR) 10.5, 95% confidence interval (CI) 5.6-19.4), as were those with HCV (RR 6.3, 95% CI 3.9-10.1), hepatitis B virus (HBV) (RR 4.2, 95% CI 1.8-9.5), and Epstein-Barr virus (EBV) (RR 10.9 95% CI 5.4-22.2). The only statistically significant increased risk for anti-β2-glycoprotein I (anti-β2-GPI) antibodies was observed in patients with HCV (RR 4.8 95% CI 1.0-22.3). Compared with patients with lupus, patients with HIV were more likely to develop elevated aCL antibodies (RR 1.8, 95% CI 1.3-2.6), and those with EBV, elevated anti-β2-GPI antibodies (RR 2.2, 95% CI 1.3-3.9). Thromboembolic events were most prevalent in patients with elevated aPL antibodies who had HCV (9.1%, 95% CI 3.0-18.1), and HBV (5.9%, 95% CI 2.0-11.9) infections, and pregnancy events were most prevalent in those with parvovirus B19 (16.3%, 95% CI 0.78-45.7). However, compared to virus-infected patients with negative aPL antibodies, the only statistically significant increased risk was observed in those with HCV and positive aPL. Conclusions Viral infection can increase the risk of developing elevated aPL antibodies and associated thromboembolic events. Results are contingent on the reported information.

Systematic review of case reports of antiphospholipid syndrome following infection

OBJECTIVE

The objective of this study was to conduct a systematic review of case reports documenting the development of antiphospholipid syndrome or antiphospholipid syndrome-related features after an infection.

METHODS

We searched Medline, EMBASE, Web of Science, PubMed ePubs, and The Cochrane Library - CENTRAL through March 2015 without restrictions. Studies reporting cases of antiphospholipid syndrome or antiphospholipid syndrome-related features following an infection were included.

RESULTS

Two hundred and fifty-nine publications met inclusion criteria, reporting on 293 cases. Three different groups of patients were identified; group 1 included patients who fulfilled the criteria for definitive antiphospholipid syndrome (24.6%), group 2 included patients who developed transient antiphospholipid antibodies with thromboembolic phenomena (43.7%), and group 3 included patients who developed transient antiphospholipid antibodies without thromboembolic events (31.7%). The most common preceding infection was viral (55.6%). In cases that developed thromboembolic events Human immunodeficiency and Hepatitis C viruses were the most frequently reported. Parvovirus B19 was the most common in cases that developed antibodies without thromboembolic events. Hematological manifestations and peripheral thrombosis were the most common clinical manifestations. Positive anticardiolipin antibodies were the most frequent antibodies reported, primarily coexisting IgG and IgM isotypes. Few patients in groups 1 and 2 had persistent antiphospholipid antibodies for more than 6 months. Outcome was variable with some cases reporting persistent antiphospholipid syndrome features and others achieving complete resolution of clinical events.

CONCLUSIONS

Development of antiphospholipid antibodies with all traditional manifestations of antiphospholipid syndrome were observed after variety of infections, most frequently after chronic viral infections with Human immunodeficiency and Hepatitis C. The causal relationship between infection and antiphospholipid syndrome cannot be established, but the possible contribution of various infections in the pathogenesis of antiphospholipid syndrome need further longitudinal and controlled studies to establish the incidence, and better quantify the risk and the outcomes of antiphospholipid-related events after infection.

The environment and antiphospholipid syndrome

The etiology of autoimmune diseases is multifactorial. The degree to which genetic and environmental factors influence susceptibility to autoimmune diseases is poorly defined. It is believed that versatile clinical presentations of autoimmune diseases stem from various combinations of the genetic and environmental factors. One of the newly diagnosed autoimmune diseases is the antiphospholipid syndrome (APS). APS is characterized by vascular thrombosis, and/or pregnancy morbidity associated with anticardiolipin (aCL), anti-β2-glycoprotein-I (anti-β2GPI) and lupus anticoagulant (LAC).

Antibodies to Phosphatidylserine/Prothrombin Complex in Antiphospholipid Syndrome: Analytical and Clinical Perspectives

Antiphospholipid syndrome (APS) is an autoimmune disorder characterized by thrombosis and/or pregnancy-related morbidity accompanied by persistently positive antiphospholipid antibodies (aPL). Current laboratory criteria for APS classification recommend testing for lupus anticoagulant as well as IgG and IgM anticardiolipin, and beta-2 glycoprotein I (anti-β2GPI) antibodies. However, there appears to be a subset of patients with classical APS manifestations who test negative for the recommended criteria aPL tests. While acknowledging that such patients may have clinical features that are not of an autoimmune etiology, experts also speculate that these "seronegative" patients may test negative for relevant autoantibodies as a result of a lack of harmonization and/or standardization. Alternatively, they may have aPL that target other antigens involved in the pathogenesis of APS. In the latter, autoantibodies that recognize a phosphatidylserine/prothrombin (PS/PT) complex have been reported to be associated with APS and may have diagnostic relevance. This review highlights analytical and clinical attributes associated with PS/PT antibodies, taking into consideration the performance characteristics of criteria aPL tests in APS with specific recommendations for harmonization and standardization efforts.

Mycobacteria and autoimmunity

Mycobacterial infections can cause a variety of different manifestations. The increasing incidence of these infections worldwide brought another medical dilemma: immunological manifestations characterized by the presence of many autoantibodies and concomitant presence of autoimmune diseases. The burden of tuberculosis reactivation that emerged with immunosuppressive therapy worsened with the growing use of biological disease-modifying antirheumatic drugs (DMARDs). This review will address the relationship between the immune system and mycobacteria.

Transient antiphospholipid syndrome associated with primary cytomegalovirus infection: a case report and literature review

Viral infection is known to induce transient autoimmunity in humans. Acute cytomegalovirus (CMV) infection is implicated in occasional thrombosis formation. We here, for the first time, report a 19-year-old female who had an acute CMV infection, leading to a deep venous thrombosis and a pulmonary embolism along with transient appearance of lupus anticoagulant. The pathological role of antiphospholipid antibodies in CMV-mediated thrombosis is discussed.

Laboratory methods to detect antiphospholipid antibodies

This chapter reviews several important themes pertaining to the antiphospholipid syndrome (APS), including a description of the clinical features, a discussion of the main autoantigen, beta 2-glycoprotein I (β2GPI), and insights into the characteristics of the pathogenic anti-β2GPI autoantibodies. Evidence-based considerations for when to test for APS are explored, along with the clinical significance of patients testing positive on multiple APS assays, so-called triple positivity. A detailed review of recently published laboratory guidelines for the detection of lupus anticoagulant and the solid-phase anticardiolipin and anti-β2GPI ELISAs is undertaken. Finally, a brief review of nonclassification criteria laboratory assays with potential future diagnostic utility is presented.

Circulating microparticles in patients with antiphospholipid antibodies: characterization and associations

The antiphospholipid syndrome is characterized by venous or arterial thrombosis and/or recurrent fetal loss in the presence of circulating antiphospholipid antibodies. These antibodies cause activation of endothelial and other cell types leading to the release of microparticles with procoagulant and pro-inflammatory properties. The aims of this study were to characterize the levels of endothelial cell, monocyte or platelet derived, and tissue factor-bearing microparticles in patients with antiphospholipid antibodies, to determine the association of circulating microparticles with anticardiolipin and anti-β2-glycoprotein antibodies, and to define the cellular origin of microparticles that express tissue factor. Microparticle content within citrated blood from 47 patients with antiphospholipid antibodies and 144 healthy controls was analyzed within 2hours of venipuncture. Levels of Annexin-V, CD105 and CD144 (endothelial derived), CD41 (platelet derived) and tissue factor positive microparticles were significantly higher in patients than controls. Though levels of CD14 (monocyte-derived) microparticles in patient plasma were not significantly increased, increased levels of CD14 and tissue factor positive microparticles were observed in patients. Levels of microparticles that stained for CD105 and CD144 showed a positive correlation with IgG (R=0.60, p=0.006) and IgM anti-beta2-glycoprotein I antibodies (R=0.58, p=0.006). The elevation of endothelial and platelet derived microparticles in patients with antiphospholipid antibodies and their correlation with anti-β2-glycoprotein I antibodies suggests a chronic state of vascular cell activation in these individuals and an important role for β2-glycoprotein I in development of the pro-thrombotic state associated with antiphospholipid antibodies.

Laboratory tests for the antiphospholipid syndrome

Antiphospholipid syndrome (APS) is an autoimmune disorder characterized by recurrent vascular thrombosis (VT) and/or pregnancy morbidity (PM) in the presence of persistent antiphospholipid antibodies (aPL), detected by lupus anticoagulant (LA), anticardiolipin (aCL) antibody, and/or anti-β₂ glycoprotein I (aβ₂GPI) antibody assays. These aPL, considered to be diagnostic markers and pathogenic drivers of APS, are a heterogeneous group of antibodies directed against anionic phospholipids, phospholipid-binding plasma proteins, and phospholipid-protein complexes. Although APS is currently considered as a single disease, it presents with a wide range of clinical symptoms and biological characteristics. The clinical diagnosis of APS in a patient with symptoms and signs is dependent upon the presence of a persistently positive result in an aPL assay. The tests recommended for detecting aPL are the standardized enzyme-linked immunosorbent assay (ELISA) to detect aCL and aβ₂GPI and clotting assays for LA performed according to the guidelines of the International Society on Thrombosis and Haemostasis. This chapter describes the standard laboratory test for the diagnosis of APS discussing the clinical and theoretical aspects of LA, aCL, and aβ₂GPI assays.

Initial Cutaneous Manifestations Associated with Histopathological Leukocytoclastic Vasculitis in Two Patients with Antiphospholipid Antibody Syndrome

Antiphospholipid antibody syndrome (APS) is a multisystem disorder associated with a variety of circulating autoantibodies that target different phospholipid protein complexes. APS is sometimes lethal as a result of severe sequelae, which may be primary or secondary to the underlying disease. We report two women who presented histopathologically with leukocytoclastic vasculitis as the first cutaneous manifestation and were subsequently diagnosed with APS associated with systemic lupus erythematosus (SLE). Patient 1 presented with widespread cutaneous necrosis (WCN) with rapidly spreading pain down the lower extremities. Skin biopsy specimens from her leg purpura and WCN revealed perivascular infiltrates with neutrophils consistent with leukocytoclastic vasculitis and thromboses of small-sized dermal vessels. Patient 2 exhibited livedo reticularis, painful cutaneous nodules with necrosis, ulcer, and erythematous macules on her lower extremities, shoulder, and face. Skin biopsies of her right knee showed intravascular thrombosis of small dermal vessels and infiltration of perivascular tissues with necrotizing granulomatous vasculitis in the dermis. We found that these various cutaneous manifestations with leukocytoclastic vasculitis were present at an early stage of APS. Although progression to leukocytoclastic vasculitis in patients with APS is uncommon, our data suggest that the association between microvascular occlusions and cutaneous vessel vasculitis has a predictive value for the pathogenesis. It is important for dermatologists to recognize these cutaneous signs to permit early and accurate diagnosis and treatment.

Antiphospholipid antibodies during 6-month treatment with infliximab: a preliminary report

BACKGROUND

The introduction of tumor necrosis factor (TNF) antagonists (adalimumab, infliximab, and etanercept) was a major advance and was highly important and beneficial in most rheumatoid arthritis (RA) patients. The adverse effects of this treatment are infrequent, but include opportunistic intracellular infection (especially the reactivation of latent Mycobacterium tuberculosis); exacerbation of demyelinating disorders; and the production of various types of antibodies such as antinuclear antibodies (ANA) or double-stranded DNA autoantibodies (dsDNA) and antiphospholipid antibodies (aPL) such as anti-cardiolipin antibodies (aCL) and anti-B2GP-I antibodies (B2GP-I). The aim of the study was to determine the prevalence of aCL and B2GP-I in IgM and IgG classes, using ELISA tests, during 6 months of follow-up in patients with refractory RA successfully treated with infliximab.

MATERIAL/METHODS

We determined the prevalence of aCL and B2GP-I in IgM and IgG classes, using ELISA tests, during 6 months of follow-up in patients with refractory RA successfully treated with infliximab.

RESULTS

We observed a statistically important increase only in the group of B2GP-I IgM (p<0.05). There are contradictory results concerning the ability of infliximab to induce aPL, but most authors confirm this phenomenon.

CONCLUSIONS

Further investigations are needed to determine if the new aPL appears in patients with β2-GPI gene polymorphisms such as leucine-to-valine substitution at position 247, which can lead to a conformational changes in β2-GPI protein, leading to aPL synthesis. The role of aPL in pathogenesis of APS is still unclear, but we should remember the immunogenic aspect of TNF antagonist treatment. Therefore, we recommend early detection of aPL and observation of the patient, paying special attention to signs and symptoms of thromboembolism.

Serology of Lupus Erythematosus: Correlation between Immunopathological Features and Clinical Aspects

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by the aberrant production of a broad and heterogenous group of autoantibodies. Even though the presence of autoantibodies in SLE has been known, for more than 60 years, still nowadays a great effort is being made to understand the pathogenetic, diagnostic, and prognostic meaning of such autoantibodies. Antibodies to ds-DNA are useful for the diagnosis of SLE, to monitor the disease activity, and correlate with renal and central nervous involvements. Anti-Sm antibodies are highly specific for SLE. Anti-nucleosome antibodies are an excellent marker for SLE and good predictors of flares in quiescent lupus. Anti-histone antibodies characterize drug-induced lupus, while anti-SSA/Ro and anti-SSB/La antibodies are associated with neonatal lupus erythematosus and photosensitivity. Anti-ribosomal P antibodies play a role in neuropsychiatric lupus, but their association with clinical manifestations is still unclear. Anti-phospholipid antibodies are associated with the anti-phospholipid syndrome, cerebral vascular disease, and neuropsychiatric lupus. Anti-C1q antibodies amplify glomerular injury, and the elevation of their titers may predict renal flares. Anti-RNP antibodies are a marker of Sharp's syndrome but can be found in SLE as well. Anti-PCNA antibodies are present in 5–10% of SLE patients especially those with arthritis and hypocomplementemia.

Clinical relevance of antibodies to cardiolipin in patients with chronic hepatitis C

The significance of antibodies to cardiolipin (anti-CL) remains uncertain in patients with chronic hepatitis C (CH-C). The main purpose of this study was to elucidate the clinical characteristics of patients with CH-C seropositive for anti-CL. The prevalence of anti-CL and clinical parameters associated with anti-CL in those patients were examined. Six of the 45 (13%) patients with CH-C had anti-CL. However, none of these six CH-C patients fulfilled the criteria for antiphospholipid syndrome. Serum triglyceride and apolipoprotein B (ApoB) levels in CH-C patients with anti-CL were significantly higher than those in CH-C patients without anti-CL. Serum triglyceride levels positively correlated with serum ApoB levels. CH-C patients with anti-CL had significantly more progressive hepatic fibrosis than those without anti-CL. The degree of 8-hydroxy 2'-deoxyguanosine (8-OHdG) expression in the liver tissue was more severe in CH-C patients with anti-CL than in those without it. However, the emergence of anti-CL in CH-C patients was independent of insulin resistance, hepatic steatosis, and iron overload. These findings suggest that the emergence of anti-CL is associated with oxidative stress and that CH-C patients seropositive for anti-CL have clinical characteristics of hypertriglyceridemia, which derives from the facilitation of ApoB synthesis, and progressive hepatic fibrosis.

Detection of anticardiolipin antibody IgG by time-resolved fluoroimmunoassay

In an effort to improve the quantitative detection of anticardiolipin antibodies (aCL) IgG so as to classify patients correctly as antiphospholipid syndrome (APS) positive, we developed a new immunoassay based on a sandwich time-resolved fluoroimmunoassay (TRFIA) using the complex of cardiolipin plus bovine β(2)GPI as antigen and Eu(3+)-labeled rabbit antihuman IgG as conjugate. The precision, sensitivity, specificity, and stability of the assay were evaluated, and comparison with the classical ELISA was also made. The aCL IgG TRFIA kit we established had a wider detectable range than three commercial ELISA ones from different manufacturers when a specimen was diluted, with strong positive result from 1:12.5 to 1:204,800. The average intra-assay and inter-assay CVs detected by the aCL IgG TRFIA was 3.14 and 3.70 %, respectively. The sensitivity was 0.1 GPL U/ml, and the clinical diagnostic specificity was 98 %. The established assay kit also behaved better in stability than the commercial ELISA ones. Additionally, the immunoassay we established correlated well with the ELISA, and the correlation coefficient was 0.975. We thus conclude that the TRFIA we developed for aCL IgG detection gives promise to a more sensitive and reliable diagnosis of APS and has potential value for large-scale screening programs.

Influenza vaccination can induce new-onset anticardiolipins but not β2-glycoprotein-I antibodies among patients with systemic lupus erythematosus

BACKGROUND

Antiphospholipid syndrome is characterized by autoantibodies against cardiolipins (aCL), lupus anticoagulant, and independent β2-glycoprotein (β2GPI). Controversy exists as to whether vaccination triggers the development of antiphospholipid antibodies (aPL) in patients with systemic lupus erythematosus (SLE).

METHODS

Patients with SLE (101) and matched controls (101) were enrolled from 2005-2009 and received seasonal influenza vaccinations. Sera were tested by ELISA for aCL at baseline, 2, 6, and 12 weeks after vaccination. Vaccine responses were ranked according to an overall anti-influenza antibody response index. Individuals with positive aCL were further tested for β2GPI antibodies.

RESULTS

Patients with SLE and healthy controls can develop new-onset aCL post vaccination, although at rates which do not differ between patients and controls (12/101 cases and 7/101 controls, OR 1.81, p = 0.34). New-onset moderate aCL are slightly enriched in African American SLE patients (5/36 cases; p = 0.094). The optical density measurements for aCL reactivity in patients were significantly higher than baseline at 2 weeks (p < 0.05), 6 weeks (p < 0.05), and 12 weeks (p < 0.05) post vaccination. No new β2GPI antibodies were detected among patients with new aCL reactivity. Vaccine response was not different between patients with and without new-onset aCL reactivity (p = 0.43).

CONCLUSIONS

This study shows transient increases in aCL, but not anti-β2GPI responses, after influenza vaccination.

A novel pathway for human endothelial cell activation by antiphospholipid/anti-β2 glycoprotein I antibodies

Antiphospholipid Abs (APLAs) are associated with thrombosis and recurrent fetal loss. These Abs are primarily directed against phospholipid-binding proteins, particularly β(2)GPI, and activate endothelial cells (ECs) in a β(2)GPI-dependent manner after binding of β(2)GPI to EC annexin A2. Because annexin A2 is not a transmembrane protein, the mechanisms of APLA/anti-β(2)GPI Ab-mediated EC activation are uncertain, although a role for a TLR4/myeloid differentiation factor 88-dependent pathway leading to activation of NF-κB has been proposed. In the present study, we confirm a critical role for TLR4 in anti-β(2)GPI Ab-mediated EC activation and demonstrate that signaling through TLR4 is mediated through the assembly of a multiprotein signaling complex on the EC surface that includes annexin A2, TLR4, calreticulin, and nucleolin. An essential role for each of these proteins in cell activation is suggested by the fact that inhibiting the expression of each using specific siRNAs blocked EC activation mediated by APLAs/anti-β(2)GPI Abs. These results provide new evidence for novel protein-protein interactions on ECs that may contribute to EC activation and the pathogenesis of APLA/anti-β(2)GPI-associated thrombosis and suggest potential new targets for therapeutic intervention in antiphospholipid syndrome.

Induction of decreased fecundity by tetanus toxoid hyper-immunization in C57BL/6 mice depends on the applied adjuvant

It has already been shown that tetanus toxoid (TTd) hyper-immunization is a suitable experimental method for creating the animal model of antiphospholipid syndrome (APS) in BALB/c mice. The severity of APS pathology in BALB/c mice mainly correlates to the affinity of anti-β2 glycoprotein I (β2GPI) antibodies. In this study we have investigated reproductive pathology induced in C57BL/6 mice by TTd hyper-immunization using a combination of different pretreatments (complete Freund's adjuvant or glycerol) and adjuvants (alhydrogel or glycerol). A decrease in fecundity was recorded in only C57BL/6 mice immunized with alhydrogel adjuvant, irrespective of the kind of applied pretreatment; it was associated with an increase in abundance of low affinity anti-β2GPI IgG antibodies and Th1 prevalence.

Lupus anticoagulant (LA) in pregnant women with history of recurrent fetal loss

The frequency of LA in 50 women with intact pregnancy, age range 26 to 39 years, but with past history of at least 2 lost pregnancies, was determined using coagulation-based assays. Most (68%) of the pregnant women were in the first trimester. Venous blood (4.5 mL) carefully collected from each of the subjects and also the controls (normal relative donors) was put in 0.5 mL of 3.8% citrate (ratio 9:1). The blood was quickly centrifuged at 1500 g; platelet-poor plasma was separated and frozen at -30°C until analyzed. The control plasma was pooled and dispensed in 2 mL aliquots. Partial thromboplastin time with kaolin (PTT(k)) (against the control samples for comparison) and kaolin clotting time (KCT) were determined on each of the test samples using standard laboratory procedures. Prolonged PTT(k) was obtained in 36 patients (72%). KCT was obtained through mixtures of patients' plasma with pooled control plasma (P:C) at 100:0; 0.8:0.2; 0.6:0.4; 0.5:0.5; 0.4:0.6; 0.2:0.8; 0:100; and lin-lin graph paper was used to plot out each of these dilutions against their respective clotting time in seconds. The interpreted graph showed that 12 (24%) had LA, while 3 (6%) had LA with cofactor. This high frequency necessitates regular screening for LA in pregnant women with a history of recurrent fetal loss at any gestational age.

Evaluation of two immunoblot assays and a Western blot assay for the detection of antisyphilis immunoglobulin g antibodies

In the present study, two immunoglobulin G (IgG) immunoblot assays and one IgG Western blot assay were compared to the rapid plasma reagin test (RPR), the fluorescent treponemal antibody absorption test (FTA-ABS), and the Treponema pallidum particle agglutination assay (TP-PA). The agreement levels of the Viramed, Virotech, and MarDx assays were 97.0%, 96.4%, and 99.4%, and the agreements of samples inconclusive by FTA-ABS and resolved by TP-PA were 91.7%, 83.3%, and 69.4%, respectively.

Anticardiolipin antibodies in patients with type 2 diabetes mellitus

BACKGROUND

There is controversy about an increased prevalence of antiphospholipid antibodies in diabetic patients. The possible implications are little known.

METHODS

We prospectively studied all consecutive outpatients with type 2 diabetes mellitus (DM) attended to in an Internal Medicine office. IgM and IgG anticardiolipin antibodies (ACA) were determined by standardized enzyme-linked immunoassay.

RESULTS

Fifty-six patients were included. Only one patient (1.8%) had a titer of IgM ACA higher than 15 MPL units and no patient had a titer of IgG ACA higher than 15 GPL units. Six patients (10.7%) had low IgM ACA titers (4-15 MPL units) and 18 patients (32.1%) had low IgG ACA titers (4-15 GPL units). There were no differences in the frequencies of a low IgM or IgG ACA titer or in the means of IgM and IgG ACA titers in patients with complicated and uncomplicated DM, with and without cardiovascular disease, with and without nephropathy, or with and without retinopathy.

CONCLUSIONS

Moderate to high ACA titers must be exceptional in patients with type 2 DM. Low ACA titers may occur in patients with type 2 DM. These low titers do not seem to be associated with complicated DM, cardiovascular disease, nephropathy or retinopathy.

Elevated anticardiolipin antibodies in schizophrenic patients before and during neuroleptic medication

The objective of this study was to examine the prevalence of IgG and IgM anticardiolipin antibodies (aCL) in schizophrenic patients and to determine the relation of aCL levels with neuroleptic medication and psychotic symptoms. Twenty-three patients with acute episodes of chronic schizophrenia, drug-free for at least 3 months before entering the study, were tested for aCL at admission (T1) and 42 days (T2) after neuroleptic treatment started. Blood samples were taken from 20 healthy volunteers as well. Diagnosis was performed according to DSM-IV. Serum samples were analysed for IgG and IgM autoantibodies against beta2-glycoprotein-1-cardiolipin complex by commercially available ELISA kits (Binding-site, UK). Significantly higher levels of aCL antibodies of both isotypes were found in schizophrenic patients versus controls. In patients IgM-aCL positivity was significantly more frequent than in controls. The elevated IgM-aCL and IgG-aCL values were not associated with neuroleptic treatment and psychotic symptoms, as measured by the Positive and Negative Syndrome Scale and the Pentagonal Structural Model of Schizophrenic Symptoms. The negative correlation of IgM-aCL and IgG-aCL with the positive symptoms scale and the autistic preoccupation scale (Pentagonal Structural Model) may indicate the consumption of these antibodies in the exacerbation of the disease.

Murine monoclonal antibody 26 raised against tetanus toxoid cross-reacts with beta2-glycoprotein I: its characteristics and role in molecular mimicry

PROBLEM

Studies on experimental antiphospholipid syndrome (APS) models proved that molecular mimicry between plasma protein beta(2)-glycoprotein I (beta(2)GPI) and structure within micro-organisms or their products, might be a cause for experimental APS. Considering the heterogeneity of polyclonal antiphospholipid antibodies (aPLs), it is important to define the precise characteristics of pathogenic aPLs. To avoid the influence of polyclonality and to further analyse the connection between molecular mimicry and APS, we produced monoclonal antibodies (MAbs) against tetanus toxoid (TTd) and tested their reactivity against beta(2)GPI.

METHOD OF STUDY

In this report, we analysed the characteristics of MAb26 raised against TTd and cross-reactive with beta(2)GPI: its binding properties in various in vitro immunoassays, its specific interactions with surface epitopes expressed on apoptotic cells and its role in vivo.

RESULTS

We have demonstrated that MAb26: (i) binds beta(2)GPI being immobilized on an appropriate surface: irradiated polystyrene plates, non-irradiated plates pre-coated with anionic phospholipids and polyvinylidene fluoride membrane; (ii) binds specifically to apoptotic but not to viable cells and the binding is beta(2)GPI-dependent; and (iii) induces a pathologic pregnancy outcome when passively injected into BALB/c mice.

CONCLUSION

This study concluded that certain subpopulations of antibodies raised against TTd and cross-reactive with beta(2)GPI, because of the molecular mimicry mechanism, could have pathologic potential.

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.

Controversies and unresolved issues in antiphospholipid syndrome pathogenesis and management

While much is understood concerning the clinical features of patients with antiphospholipid syndrome (APS), many issues remain. The proper designation of patients with "definite" APS and the correct categorization of patients by both laboratory and clinical features are matters of ongoing debate. Recent proposals have identified new subsets of patients who have many typical features of APS but either do not fit the criteria for a "definite" diagnosis or have initially negative laboratory tests for antiphospholipid antibodies. Meanwhile, decisions about laboratory tests are based on expert opinion, rather than the results of controlled trials. As for treatment, many guidelines are offered, but few are backed by data from strong clinical trials. This article summarizes the clinical questions remaining to be answered and debates concerning pathogenesis, diagnosis, and management.

Antiphospholipid syndromes in infectious diseases

Antiphospholipid antibodies are essential in the diagnosis of antiphospholipid syndrome (APS), or the classic "Hughes syndrome," which is a systemic disorder that is autoimmune in nature. They are also found in various infections in low titers without any evidence of thrombotic manifestations of APS. However, in a few infections, when antiphospholipid antibodies are associated with protein cofactor, there can be associated thrombosis. Different infections are also responsible for triggering a subset of lethal APS, acute catastrophic APS. This situation requires prompt diagnosis and aggressive treatment of the infection to prevent severe complications.

Antiphospholipid antibodies in pediatric systemic lupus erythematosus and the antiphospholipid syndrome

The antiphospholipid syndrome (APS) is recognized increasingly as the most common acquired hypercoagulation state of autoimmune etiology and may occur as an isolated clinical entity (primary APS) or in association with an underlying systemic disease, particularly systemic lupus erythematosus (SLE). The major differences between pediatric and adult APS include absence of common acquired risk factors for thrombosis, absence of pregnancy-related morbidity, increased incidence of infection-induced antibodies, differences in cut-off values for determination of aPL and specific factors regarding long-term therapy in children. APS in children has been largely reported in patients with arterial or venous thromboses and less frequently in association with neurological or hematological manifestations. The presence of aPL in pediatric SLE can modify the disease expression and may be an important predictor of the development of irreversible organ damage. Two recently established international registries of neonates and children with APS provide a good opportunity to conduct large, prospective studies on the clinical significance of aPL and long-term outcome of pediatric APS.

Antiphospholipid antibodies, antiphospholipid syndrome and infections

Since the association between antiphospholipid antibodies (aPL) and syphilis was first described, many other viral, bacterial and parasitic infections have been shown to induce antiphospholipid antibodies, notably anticardiolipin antibodies (aCL). A review of the literature shows that while aCL occur frequently in viral infections, particularly in HIV (49.75%), HBV (24%) and HCV (20%), it is very rarely associated with anti-beta2 glycoprotein I antibodies (anti-beta2GPI) and is not correlated with thrombosis risk or hematological manifestations of the antiphospholipid syndrome (APS). Concerning bacterial infections, aCL is often present in leprosy (42.7%), where it is frequently associated with the presence of anti-beta2GPI (44.8%), and in syphilis infections (8 to 67%), though without correlation with thrombotic events. Though few individual patients with unequivocal infection-induced aPL satisfy criteria for APS, the lack of statistical association with thrombotic events strongly argues against the identification of a true APS subset in this context. However, physicians should keep in mind the fact that an infection, generally bacterial, in patients with confirmed APS, may lead to catastrophic antiphospholipid syndrome with a possible fatal outcome.

The role of antibody polyspecificity and lipid reactivity in binding of broadly neutralizing anti-HIV-1 envelope human monoclonal antibodies 2F5 and 4E10 to glycoprotein 41 membrane proximal envelope epitopes

Two neutralizing human mAbs, 2F5 and 4E10, that react with the HIV-1 envelope gp41 membrane proximal region are also polyspecific autoantibodies that bind to anionic phospholipids. To determine the autoantibody nature of these Abs, we have compared their reactivities with human anti-cardiolipin mAbs derived from a primary antiphospholipid syndrome patient. To define the role of lipid polyreactivity in binding of 2F5 and 4E10 mAbs to HIV-1 envelope membrane proximal epitopes, we determined the kinetics of binding of mAbs 2F5 and 4E10 to their nominal gp41 epitopes vs liposome-gp41 peptide conjugates. Both anti-HIV-1 mAbs 2F5 and 4E10 bound to cardiolipin with K(d) values similar to those of autoimmune anti-cardiolipin Abs, IS4 and IS6. Binding kinetics studies revealed that mAb 2F5 and 4E10 binding to their respective gp41 peptide-lipid conjugates could best be defined by a two-step (encounter-docking) conformational change model. In contrast, binding of 2F5 and 4E10 mAbs to linear peptide epitopes followed a simple Langmuir model. A mouse mAb, 13H11, that cross-blocks mAb 2F5 binding to the gp41 epitope did not cross-react with lipids nor did it neutralize HIV-1 viruses. Taken together, these data demonstrate the similarity of 2F5 and 4E10 mAbs to known anti-cardiolipin Abs and support the model that mAb 2F5 and 4E10 binding to HIV-1 involves both viral lipid membrane and gp41 membrane proximal epitopes.

Lupus anticoagulant and anticardiolipin antibodies in polytransfused beta thalassemia major

The currently used therapeutic strategies in beta thalassemia have prolonged the survival for many patients; this longer survival has been accompanied by the development of a number of unexpected complications, these include hemostatic derangements. The presence of anti-phospholipid antibodies (APA) (lupus anticoagulant, LA and anti-cardiolipid antibody, ACA) has recently been reported in polytransfused patients of beta thalassemia. In this study 50 patients with beta thalassemia major (beta-TM) who had received at least 20 transfusions were evaluated for presence of antiphospholipid antibodies and correlated with a number of clinical and hemostatic parameters. About 32% cases had developed a minor bleeding tendency and one also showed ecchymotic patch. None of the patients had thromboembolic episodes. LA was seen in 16% of cases. The mean age and number of transfusions were higher in LA positive patients as compared to LA negative patients however the results were not statistically significant. IgM ACA were detected in 6% of patients but no statistically significant correlation was found with age, number of transfusions, platelet count and coagulation parameters. IgG ACA were detected in 30% of cases and showed a significant correlation with number of blood transfusions (p = 0.016) and age (p = 0.031). Anti HCV antibodies were detected in 30% of patients out of which 1 had IgM ACA and 10 had IgG ACA. The latter showed a significant correlation with HCV infection. An increased incidence of LA and IgG ACA is found in polytransfused patients with beta-TM when compared to the normal healthy population but their clinical significance is yet not clearly understood.

IgG and IgM anticardiolipin antibodies following treatment with infliximab plus methotrexate in patients with early rheumatoid arthritis

OBJECTIVE

To assess the occurrence of anticardiolipin antibodies (aCL) in patients with early rheumatoid arthritis (RA) receiving treatment with infliximab plus methotrexate (MTX) versus MTX alone.

METHODS

The first 299 patients enrolled in the randomized, Active-Controlled Study of Patients Receiving Infliximab for the Treatment of Rheumatoid Arthritis of Early Onset (ASPIRE) trial who had baseline (week 0) samples available for aCL testing were included in this study. Sera were collected at weeks 0, 30, and 54 from 110 patients taking infliximab 3 mg/kg plus MTX, 98 patients taking infliximab 6 mg/kg plus MTX, and 91 patients taking placebo plus MTX. IgG and IgM aCL were measured using an anticardiolipin assay.

RESULTS

IgG and IgM aCL positivity at baseline was similar in all treatment groups. Most patients were negative for IgG aCL at baseline and remained so at the last followup evaluation. One percent (2 of 208) of patients who received infliximab plus MTX and were negative for IgG aCL at baseline were positive for IgG aCL at weeks 30 and 54. A slightly higher proportion of patients who received infliximab plus MTX and were negative for IgM aCL at baseline were positive for IgM aCL at weeks 30 and 54 (4.8% [10 of 208]) as compared with patients who received placebo plus MTX (1.1% [1 of 91]), but the difference was not significant.

CONCLUSION

There was a low incidence of the development of aCL in patients with early RA who received infliximab in combination with MTX, and the difference was not significant compared with patients who received placebo plus MTX.

Current concepts on the pathogenesis of the antiphospholipid syndrome

The antiphospholipid syndrome (APS) is an important cause of acquired thrombophilia. It is characterized by the core clinical manifestations of thrombosis, either venous or arterial, and in women it can also be associated with recurrent fetal loss. The detection of persistently elevated levels of antiphospholipid antibodies (aPL Abs) is a requisite laboratory feature for the diagnosis to be made. The dominant antigenic targets in APS are beta 2-glycoprotein I (β2-GPI) and prothrombin. There is an accumulating body of experimental evidence that suggests that specific subgroups of aPL Abs may directly contribute to disease pathogenesis. This review critically examines the experimental evidence underlying the various propositions made to explain how these antibodies may predispose to disease in humans. Furthermore, it also examines the evidence relating to the immunologic mechanisms that may contribute to the breakage of peripheral tolerance in this disorder. Delineating the strengths and limitations of the experimental evidence accumulated thus far will hopefully stimulate further experimentation toward achieving the ultimate goal of precisely defining the dominant pathogenic mechanisms operational in APS. This may pave the way for the development of improved therapies.

Elevated serum IgA anticardiolipin antibody levels in adult Henoch-Schönlein purpura

BACKGROUND

Henoch-Schönlein purpura (HSP) is a small-vessel vasculitis characterized by palpable purpura on the lower extremities and IgA-dominant immune complex deposition within the wall and lumen of dermal vessels in the lesions. This disorder is associated, to varying degrees, with joint, gastrointestinal and renal involvement. Antiphospholipid antibodies, including anticardiolipin antibodies (aCL Abs), are a heterogeneous group of circulating autoantibodies found in patients with autoimmune and infectious diseases.

OBJECTIVES

To investigate the possible role of aCL Abs in adult HSP, we measured levels of serum IgA, C-reactive protein (CRP), aCL Abs of the IgG, IgM and IgA isotypes and anti-beta(2)-glycoprotein I (beta(2)GPI)-dependent aCL Abs in adult patients with HSP. We evaluated the correlation between these biological parameters and the clinical manifestations.

METHODS

Adult patients with HSP with an initial cutaneous manifestation of palpable purpura on their lower extremities seen between 2001 and 2005 in our department were retrospectively reviewed. Patients with known connective tissue diseases were not included in the study. Histological examination of all patient skin biopsy specimens revealed leucocytoclastic vasculitis in the upper and mid-dermis. Direct immunofluorescence analysis showed prominent deposits of IgA in the capillary walls of all patients. Blood samples were taken at the time that the patient presented. Serum levels of aCL Abs and anti-beta(2)GPI-dependent aCL Abs were measured by enzyme-linked immunosorbent assay.

RESULTS

Twenty adult patients with HSP (12 men and eight women), mean age 62.2 years (range 23-81) were enrolled. IgA aCL Abs were found in 15 of the 20 patients (75%). All were negative for IgG aCL Abs, IgM aCL Abs and anti-beta(2)GPI-dependent aCL Abs. The elevation of serum IgA aCL Abs in the 15 patients showed a significant correlation with serum IgA and CRP levels (r(s) = 0.91, P = 0.0007; r(s) = 0.80, P = 0.0026, respectively). Levels of serum IgA aCL Abs were also significantly associated with arthralgia (P = 0.022) and proteinuria according to urinalysis (P = 0.013).

CONCLUSIONS

Serum levels of IgA aCL Abs are elevated in the initial active stage of adult HSP, suggesting that serum IgA aCL Abs may play some role in the onset of adult HSP. We believe that serum IgA aCL Abs might be an indicator of adult HSP activity.

Cerebrovascular disease associated with antiphospholipid antibodies: more questions than answers

Neurological syndromes occur in a significant number of patients with antiphospholipid antibodies. The optimal management for these patients however remains uncertain.

Our study is a descriptive analysis looking retrospectively at 45 patients who presented to the principal tertiary referral centre in the Australian Capital Territory, with either cerebral arterial or venous thrombosis for which there was no obvious cause for their presentation when initially reviewed. The diagnosis was based on the clinical findings made by one of three neurologists attached to our centre. Radiological findings and the presence of either IgM or IgG anticardiolipin antibodies, IgG anti-beta-2 glycoprotein 1 antibodies or a lupus anticoagulant were then documented.

In this group of patients three subgroups were identified:

1. Individuals that fulfilled the Sapporo Classification Criteria

2. Individuals with transiently positive antiphospholipid antibodies and

3. Individuals with persistently low positive antiphospholipid antibodies.

The most interesting of these three groups are those individuals with transiently positive antiphospholipid antibodies. A potential cause for presentation was identified in only one patient of this group with documented infective endocarditis and bacteraemia. Comparison with the other two groups suggested that there was little in terms of clinical presentation, radiological findings or intercurrent risk factors for thrombotic disease to distinguish between them. With disappearance of antiphospholipid antibodies, the individuals within this group have not had further thrombotic events.

Our observations emphasise the problems that continue to exist in relation to the occurrence of cerebrovascular disease in the context of antiphospholipid antibodies and the optimal management of these stratified groups. Our findings also raise an as yet unanswered question as to the signficance of these transiently positive antiphospholipid antibodies. In the absence of significant intercurrent risk factors our findings would suggest that in the group we describe that they are likely to be of clinical significance.

The association of anti-phospholipid antibodies with parity in placental malaria

Anti-phospholipid antibodies (aPL) are autoantibodies associated with both infections and the pathogenesis of certain pregnancy complications. In the latter, but not the former, aPL are dependent on a co-factor, beta(2) glycoprotein I (beta2GPI), which can also be used as an antigen for detection of such aPL in pregnancy. A cross-sectional study was carried out on serum samples from Kumasi, Ghana, to determine the occurrence and beta2GPI-dependence of aPL in placental malaria. Anti-cardiolipin, anti-phosphatidylserine and anti-beta2GPI enzyme-linked immunosorbent assays (ELISAs) were performed on sera from 103 HIV-non-infected gravid women. Placental malaria, both active and past infection, was diagnosed in 33/103 (32%) based on placental histology. In multiparae, beta2GPI-independent IgM antibodies to cardiolipin (P = 0.018) and phosphatidylserine (P = 0.009) were observed, which were most pronounced in past placental malaria infection. In primiparae, no association emerged between aPL and placental malaria. Trends for improved clinical parameters were identified in infected women with levels of anti-cardiolipin beyond the 99th multiple of the median for a healthy, non-malarious population. This study in placental malaria reports parity associations of beta2GPI-independent aPL profiles, and does not support a role for beta2GPI-dependent aPL. It is of significance in the context of the known parity differences in pregnancy malaria immunity.