aPL Specificities Research Articles

Profile of antiphospholipid antibodies and complement system in COVID-19 patients of different severity

COVID-19, a severe acute respiratory syndrome caused by SARS-CoV-2, may predispose to thrombotic events, especially when combined with antiphospholipid antibodies (aPL). However, there are limited data on prevalence and antigenic specificity of aPL in COVID-19. Complement activation is assumed to play an important role in pathogenesis of COVID-19-associated coagulopathy. During the SARS-CoV-2 pandemic, it is necessary to identify important biomarkers for predicting severe course of COVID-19 and risk of thrombotic complications. Our objective was to evaluate the aPL profile, quantitative content and activity of complement and its components in COVID-19 patients graded by severity in the course of time. IgM and IgG antibodies to cardiolipin (CL), phosphatidylserine (PS), β2-glycoprotein-I (β2-GP-I), prothrombin (PT), annexin V (An V), as well as C1q complement component, content of its C3 and C4 components and total complement activity were determined in blood serum using ELISA approach. 141 patients with COVID-19 were included in the study. Group 1 consisted of 39 patients with mild form, group 2 (65 patients) presented with moderate form, and group 3 included 37 patients with severe form of COVID-19. Blood samples were obtained on day 3-7 of the disease (1st point) and after 14-28 days (2nd point). The results were as follows: aPL were detected in 29.1% of the total COVID-19 cohort, frequency of aPL detection by the severity grade did not differ (33.3%, 24.6% and 32.4%). In 8.5% of the patients, aPL were detected only at the 1st time point; in 14.2%, only at the 2nd point; and in 6.4% of the cases, at the both time points. Antibodies to PT (16.3%) and An V (11.3%) were revealed more frequently. The detection frequency of antibodies to PT was significantly higher than antibodies to CL and PS (7.1%), β2-GP-I (7.8%). The prevalence of aPL in groups 1 and 3 did not differ. At the 1st point in group 3, increased levels of C4 (89.2%) and C3 (24.3%) in blood, and a decrease in complement activity (35.1%) were more often observed than in group 1. At the 2nd time point in group 3, a decrease in complement activity was often detected (59.5%). The C3 levels exceeding 720 μg/ml were found to predict a 2.6-fold increased risk of severe COVID-19, and this risk became 3.3 times higher at C4 levels of > 740 μg/ml. The antibodies to PT and An V are often detected in COVID-19 patients, along with low prevalence of antibodies to CL and β2-GP-I. These antibodies can be involved in pathogenesis of COVID-19-associated coagulopathy, being detectable at the late stage of the disease, and they may trigger APS in predisposed patients and reconvalescents. Although presence of aPL antibodies is not associated with COVID-19 severity, their persistence over the period of convalescence may be an additional risk factor for thromboembolic complications. The COVID-19 patients are characterized by activation of the complement system, which increases in severe cases, and manifests with increased or decreased levels of C3 complement component, increased levels of C4 component in blood, and a decreased total complement activity. Quantitative determination of C3 and C4 complement components over the period of COVID-19 progression is of prognostic value, with respect to severity of the disease.

Evaluation of novel assays for the detection of autoantibodies in antiphospholipid syndrome.

Patients with antiphospholipid syndrome (APS) present with clinical features of recurrent thrombosis and pregnancy morbidity and persistently test positive for the presence of antiphospholipid antibodies (aPL). At least one clinical (vascular thrombosis or pregnancy morbidity) and one lab-based (positive test result for lupus anticoagulant, anticardiolipin antibodies and/or anti-β2-glycoprotein 1 antibodies) criterion have to be met for a patient to be classified as having APS. Nevertheless, the clinical variety of APS encompasses additional signs and symptoms, potentially affecting any organ, that cannot be explained exclusively by a prothrombotic state. Those manifestations, also known as extra-criteria manifestations, include haematologic (thrombocytopenia and haemolytic anaemia), neurologic (chorea, myelitis and migraine) manifestations as well as the presence of livedo reticularis, nephropathy and valvular heart disease. The growing body of evidence describing the clinical aspect of the syndrome has been paralleled over the years by emerging research interest focusing on the development of novel biomarkers that might improve the diagnostic accuracy for APS when compared to the current aPL tests. This review will focus on the clinical utility of extra-criteria aPL specificities. Besides, the promising role of a new technology using particle based multi-analyte testing that supports aPL panel algorithm testing will be discussed. Diagnostic approaches to difficult cases, including real-world case studies investigating the diagnostic added value of extra criteria aPL, particularly anti-phosphatidylserine/prothrombin, will also be examined.

Cofactor-Independent Antiphospholipid Antibodies: Implications for Pathogenesis, Diagnosis, and Treatment of Antiphospholipid Syndrome.

The antiphospholipid syndrome (APS) has occupied haemostaseologists, rheumatologists and obstetricians since its initial description 35 years ago. Its name has been coined because of the antibodies against phospholipids which were the common property of affected patients. In particular, the pathogenesis of APS has been intensively studied after the early discovery that it was possible to induce the clinical manifestations in animals by transfer of antiphospholipid antibodies (aPL). In recent years, it has become clear that aPL are not only structurally heterogeneous but also have different pathogenic properties. This review will focus on the relevance of antigenic specificity of aPL in terms of pathogenesis, diagnosis, and perhaps treatment of APS.

Recent advances in understanding antiphospholipid syndrome.

Antiphospholipid syndrome (APS), also known as Hughes Syndrome, is a systemic autoimmune disease characterized by thrombosis and/or pregnancy morbidity in the presence of persistently positive antiphospholipid antibodies. A patient with APS must meet at least one of two clinical criteria (vascular thrombosis or complications of pregnancy) and at least one of two laboratory criteria including the persistent presence of lupus anticoagulant (LA), anticardiolipin antibodies (aCL), and/or anti-b2 glycoprotein I (anti-b2GPI) antibodies of IgG or IgM isotype at medium to high titres in patient’s plasma. However, several other autoantibodies targeting other coagulation cascade proteins (i.e. prothrombin) or their complex with phospholipids (i.e. phosphatidylserine/prothrombin complex), or to some domains of β2GPI, have been proposed to be also relevant to APS. In fact, the value of testing for new aPL specificities in the identification of APS in thrombosis and/or pregnancy morbidity patients is currently being investigated.

The Role of Anti-Phosphatidylserine/Prothrombin Antibodies in Thrombotic Manifestations of Systemic Lupus Erythematosus Patients

Sir, In their recent article, published in Frontiers in Neurology, Mullen et al. (2012) demonstrated that anti-phosphatidylserine/prothrombin (PS/PT) antibodies are independently associated with stroke or death in non-antiphospholipid syndrome (APS) patients with transient ischemic attacks (TIA). Despite thorough statistics, the authors mention that these findings should be cautiously interpreted, since only two patients had positive IgG anti-PS/PT antibodies and a clinical event. We have recently assessed the influence of this antiphospholipid antibody (aPL) specificity in the clinical phenotype of systemic lupus erythematosus (SLE) patients. In this regard, we evaluated 35 lupus patients (33 females/2 males, mean age 37.5 ± 8.8 years, mean disease duration 103.8 ± 55.1 months) and one female non-lupus patient (33 years old), according to a previous history of thrombotic complications (arterial and/or venous thrombosis, spontaneous abortions) and other aPL-related manifestations, such as thrombocytopenia and livedo reticularis. Anti-PS/PT antibodies were measured, shortly after the clinical event, by ELISA (AESKULISA, Serin Prothrombin GM, REF 3226). Other aPL specificities, such as anticardiolipin antibodies (ACA), anti-b2GPI antibodies, and lupus anticoagulant (LA) were also assessed. Positive anti-PS/PT antibodies (>18 U/ml) were detected in 11/35 patients (31.4%), 7 with IgG anti-PS/PT, 1 with IgM anti-PS/PT, and 3 with concomitant IgM and IgG anti-PS/PT. From these patients, seven had a recent history of vascular thrombosis, while the remaining four had other aPL-related symptoms and end-stage renal disease (1/11), recurrent serositis (2/11), and false positive serological reactions for syphilis (1/11) respectively. It should be mentioned that these four patients had the lower titers of anti-PS/PT antibodies (marginally positive). Ten out of 11 patients were simultaneously positive for other aPL, such as ACA and anti-b2GPI antibodies. All patients with thrombosis were premenopausal women and had central nervous system involvement (4/7 multiple infarcts, 1/7 psychosis, 1/7 seizures, and 1/7 posterior reversible leukoencephalopathy syndrome, PRES). Of note, the three latter patients had no visible infarcts in brain MRI but detectable cerebral flow abnormalities in single-photon emission computed tomography (SPECT). None of these patients had traditional atherosclerotic risk factors. High titers of anti-PS/PT antibodies (IgM and IgG) were also detected in the sole non-lupus patient in three separate cases. This patient manifested cerebrovascular disease (multiple infarcts), in the absence of atherosclerotic risk factors and other aPL. In this case a diagnosis of APS was made, based in the presence of these antibodies. These findings come in agreement with previous reports demonstrating that the anti-PS/PT antibodies are strongly related to venous and/or arterial thrombotic manifestations in SLE patients and, particularly, cerebral infarctions (Nojima et al., 2006; Nojima et al., 2004). On a pathophysiologic basis, a possible synergistic action of the anti-PS/PT, ACA, and anti-b2GPI antibodies in the induction of ADP-mediated platelet aggregation has been proposed (Nojima et al., 2004). In accordance with these results, Syuto et al. (2009) showed that these antibodies are more frequently (and in higher titers) detected in patients with neuropsychiatric SLE in general. Our results, although restricted in SLE, confirm the findings of Mullen et al. (2012) that anti-PS/PT antibodies may serve as a surrogate marker for unfavorable outcome in TIA and may represent a subsequent stage in disease evolution in lupus patients. Given that, in many patients, TIA may not become clinically apparent, it could be hypothesized that anti-PS/PT antibodies (present in a lupus patient with quiescent TIA) may lead, over time, to multiple infarcts or to subclinical cerebral flow disturbances, which can predispose to the development of other neuropsychiatric SLE features. The authors also underline that it is difficult to determine if the mechanism behind anti-PS/PT antibodies and cerebrovascular events is primarily thrombotic or atherosclerotic. In our study, where all patients were premenopausal women and had no traditional atherosclerotic risk factors, it could be assumed that thrombosis, rather than atherosclerosis, represents the main pathophysiologic mechanism. In conclusion, anti-PS/PT antibodies seem to be strongly related to ischemic/thrombotic cerebrovascular events. Evaluation of their predictive ability and stratification of patients with TIA, in large scale prospective studies, is warranted.

Heparin or aspirin or both in the treatment of recurrent abortions in women with antiphospholipid antibody (syndrome)

Presence of antiphospholipid antibodies (aPL) is associated with unsuccessful pregnancy outcome. Based on an early concept of aPL-induced thrombophilia and placental thrombosis, antithrombotic interventions have been used to reduce incidence of miscarriage in antiphospholipid antibody syndrome (APS). The aim of this review is to summarize current knowledge on pathogenesis of miscarriage in APS and the impact of different antithrombotic therapy strategies. Pathogenetic concepts on miscarriage in APS comprise aPL-mediated cell activation, disturbance of coagulation along with increased complement activation. There is increasing evidence that heparin exerts its effect by inhibiting complement activation rather than by its anticoagulation capacity. In this regard, the outcome of pregnancies in APS has considerably improved by the invention of therapies using combinations of aspirin, unfractionated heparin (UFH) and/or low molecular weight heparin (LMWH). However, there is no clear evidence as to which treatment regimen should be preferred. Some studies indicate superiority of aspirin plus heparin over aspirin-only. Whether heparin-only treatment would confer equal effects and whether UFH and LMWH were of comparable efficacy currently is unknown. Treatment with aspirin and heparin decreases the risk of miscarriages in APS. Well designed trials as well as better patients-at-risk profiling are warranted that identify which treatment strategy should be favored and whether detailed characterization of aPL specificities could help in individualizing therapy.

Structural and functional characterization of a human IgG monoclonal antiphospholipid antibody

Antiphospholipid antibodies (aPL) are likely involved in the pathogenesis of the antiphospholipid syndrome (APS). This study analyzes the structural and functional characteristics of a human monoclonal aPL (HL7G) from the IgG2 subtype with λ light chains generated from a patient with primary APS and recurrent cerebral microemboli. DNA encoding the variable region of heavy and light chains of the antibody was sequenced, analyzed, and compared to HL5B a previously described monoclonal aPL from the same patient. Both antibodies are derived from the same germline genes. HL7G had similar but more extensive somatic mutations in the CDR1 and 2 regions than HL5B, indicating that both antibodies are closely related and derived by a T cell-dependent antigen driven process. In ELISA assays HL7G bound to cardiolipin and several other phospholipid antigens in the absence of protein cofactors. Different from HL5B this aPL bound to β2-glycoprotein I (β2GPII). This suggests that reactivity of aPL against β2GPI is determined by only few specific amino acid exchanges. HL7G was able to induce tissue factor (TF) as one of the procoagulant effects of aPL. Our data suggest that the binding specificity of aPL is only of limited value to predict the biological effect and the pathophysiological impact of the antibodies.

Redox-reactive antiphospholipid antibody differences between serum from Alzheimer's patients and age-matched controls

There is no universally acceptable inclusive laboratory biomarker for the diagnosis and staging of neurodegenerative diseases, for example, Alzheimer's. There is an abnormal increase of oxidative stress in the central nervous system (CNS) of Alzheimer's patients that causes oxidation of proteins, lipids and DNA. We have published that the antiphospholipid (aPL) autoantibodies that are members of the redox-reactive autoantibody (R-RAA) family, are significantly decreased or absent in the cerebrospinal fluids of autopsy-confirmed Alzheimer's disease (AD) patients. Because of the known elevation of oxidation-induced damage in the CNS and the abnormal enrichment of redox reactive metals in postmortem AD brains, we questioned if the R-RAA in the blood of AD patients might also show a departure from the normal aPL levels. We compared 16 AD serum samples to 17 serum samples, from age-matched volunteer blood donors. Each serum was tested before and after oxidation for four aPL specificities by using an in-house ELISA. Comparisons between the AD and normal populations revealed highly significant differences. In-sample Fisher's linear discriminate analysis found a sensitivity of 88% and a specificity of 94%. In-sample Classification and Regression Tree analysis (CART) found a sensitivity of 84% and a specificity of 100%. This study is the first to indicate that blood tests for R-RAA may be used as a laboratory criterion for an Alzheimer's diagnosis.

Clinical relevance of multiple antibody specificity testing in anti-phospholipid syndrome and recurrent pregnancy loss

We wanted to evaluate whether testing for anti-phosholipid antibodies other than anti-cardiolipin (aCL) and anti-beta-2 glycoprotein I (abeta2GPI) immunoglobulin (Ig)G and IgM identifies patients with recurrent pregnancy loss (RPL) who may be positive for anti-phospholipid syndrome (APS). In a cross-sectional study comprising 62 patients with APS, 66 women with RPL, 50 healthy blood donors and 24 women with a history of successful pregnancies, we tested IgM and IgG antibodies to phosphatidic acid, phosphatidyl choline, phosphatidyl ethanolamine, phosphatidyl glycerol, phosphatidyl inositol and phosphatidyl serine with and without beta-2 glycoprotein I (beta2GPI) from a single manufacturer as well as aCL and abeta2GPI antibodies. Diagnostic accuracies of individual and combined anti-phospholipid (aPL) assays were assessed by computing sensitivities, specificities, positive predictive values and negative predictive values together with their 95% confidence intervals. There was a general trend for increased sensitivities in the presence of beta2GPI co-factor with significant effect for certain specificities. The overall combined sensitivity of the non-recommended aPL assays was not significantly higher than that of the aCL and aB2GPI tests. Multiple aPL specificities in RPL group is not significantly different from controls and therefore of no clinical significance.

Antiphospholipid antibodies in blood and cerebrospinal fluids of patients with psychosis

Antiphospholipid antibodies (aPL) have been reported in the cerebrospinal fluids (CSF) of neurology patients but no CSF studies with psychiatric patients exist. We tested serum from 100 hospitalized psychotic patients having hallucinations and/or delusions for aPL. Patients with positive serum aPL findings were asked to submit CSF for aPL testing. Five CSF samples had aPL specificities not found in the patient's serum suggesting the possibility of intrathecal synthesis. Specificity and isotype discordance between CSF and blood aPL in these psychiatric patients implicates a central nervous system independent autoimmune process that may have an underlying association with the pathophysiology of their diseases.

Genetics of antiphospholipid syndrome

Antiphospholipid syndrome (APS) is an autoimmune disease characterized by recurrent arterial or venous thrombosis or fetal loss and the presence of antiphospholipid antibodies (aPL). Genetic factors are thought to play a role in the susceptibility to APS. Similar to many other polygenic autoimmune diseases, human leukocyte antigen associations have been reported. The genetics of b(2)-glycoprotein I, one of the most representative target antigens of aPL, has been extensively studied. Additional genetic risk factors for the development of thrombosis in patients with aPL have also been discussed. However, the genes involved in APS have not been identified because antigen specificity of aPL and the pathophysiology of APS are highly heterogeneous and multifactorial. Genome-wide linkage analysis and larger cohort studies would lead to better understanding of the genes that might be involved in APS.

The appearance and disappearance of antiphospholipid autoantibodies subsequent to oxidation–reduction reactions

The mechanisms that cause the appearance of autoantibodies are not understood. Compared to normal antibody production, factors responsible for autoantibody synthesis are more complex; they are thought to disrupt the normal mechanisms proposed to eliminate or down-regulate self-antibodies or to interfere with anti-self-receptor editing. Data presented show that autoantibodies exist in the blood of all normal individuals. The autoantibodies appear after simple oxidation–reduction (redox) reactions and react by ELISA, immunofluorescence, flow cytometry, Western blots, and in lupus anticoagulant (LA) assays. Antiphospholipid antibody (aPL) specificities detected after redox are cardiolipin (aCL), antiphosphatidylserine (aPS), antiphosphatidylethanolamine (aPE), antiphosphatidylcholine (aPC), and LA. These antibody activities were confirmed in several outside laboratories. The aPL isotypes detected in ELISA are plasma protein-dependent and include IgG, IgA, and IgM. Oxidizing agents tested to date include hemin, KMnO 4, and NaIO 4. Furthermore, aPL appear after exposure to direct current (DC)-mediated electromotive force. Alternating current (AC) is ineffective. Commercial IvIg preparations, also a source of IgG autoantibodies, provide a less complex milieu than plasma or serum for studying the biology of aPL redox-mediated mechanisms. Inhibition of hemin-mediated IvIg aPL conversion can be achieved by the addition of antioxidants, e.g., ascorbic acid, hemopexin, apotransferrin, and by addition of normal plasma or serum. Remarkably, the aPL specificities in the blood of autoimmunity patients disappear subsequent to application of redox reactions. These data document the hitherto unknown existence of redox-reactive autoantibodies in all normal individuals. The evolutionary persistence of these redox-sensitive antibodies raises interesting possibilities about their potentially beneficial role in immunological homeostasis.

Testing for antiphospholipid antibody (aPL) specificities in retrospective "normal" cerebral spinal fluid (CSF).

Antiphospholipid antibodies (aPL) have been found in the blood of patients with systemic and neurological disease. The rare reports of aPL in cerebral spinal fluid (CSF) have been limited mostly to IgG and IgM anticardiolipin (aCL). Our published finding of IgA aPE in the CSF of a young stroke victim prompted us to establish “normal” CSF aPL values for a panel of aPL, which included aCL, antiphosphatidylserine (aPS), antiphosphatidylethanolamine (aPE) and antiphosphatidylcholine (aPC). CSF samples were tested by ELISA for IgG, IgM and IgA aPL. In addition, the CSF samples were tested for activity in the presence and absence of phospholipid (PL) binding plasma-proteins. A total of 24 data points were obtained for each CSF sample.We tested 59 CSF samples obtained from 59 patients who were undergoing evaluation for systemic or neurologic diseases. All CSF samples had normal protein, glucose and cell counts. Ten of the 59 CSF samples (17%) had elevated aPL optical density (OD) values an order of magnitude higher than the other 49 CSF samples for one or more aPL specificity and/or isotype. One CSF sample had both PL-binding protein dependent and independent IgG aPE activity. Another CSF sample showed both IgG aPE and aPC reactivity. The remaining eight CSF samples showed single aPL findings; IgG aPE (5), IgG aPC (1), IgG aCL (1) and IgM aPC (1). Seven of 10 patients with elevated CSF values were females. As expected, most “normal” aPL OD values were substantially lower in CSF than those we have reported in blood samples from volunteer blood donors.

Detection of bilayer phospholipid-binding antibodies using flow cytometry.

Antiphospholipid antibodies (APL) are usually detected using solid-phase immunoassays, where cardiolipin is the most common capture antigen. Phosholipids are believed to adopt a monolayer organization when coated onto polystyrene after evaporation of the solvent. However, bilayer phospholipids are probably those evidenced as microparticles or cell fragments circulating in vivo under various pathological circumstances. The surface density of monolayer phospholipids on polystyrene is six times lower than that of bilayer phospholipids. In order to assess the influence of phospholipid organization on the detection of APL, we prepared glass microspheres coated with bilayer phospholipids (cardiolipin, phosphatidylcholine, cholesterol). Such lipospheres enabled us to study the binding of antibodies in 1:100 diluted plasma samples from patients with anticardiolipin antibodies of IgG isotype previously diagnosed by ELISA. Among the 39 plasma samples analysed by flow cytometry, 17 showed positive IgG binding to lipospheres. Only four additional samples became positive when adding 20 micrograms/ml apolipoprotein H. The specificity of the binding was demonstrated by complete reversibility with 1.4 microM annexin V and with a large excess of liposomes of the same composition. The absence of correlation between liposphere and ELISA results suggests that different subgroups of antibodies are detected depending on the method. The detection of APL using bilayer phospholipids is an original assay and may represent a more physiopathological approach to the specificity of APL.

Antiphospholipid antibodies and renal transplantation: a risk assessment.

Data from 110 transplanted patients show that the presence of antiphospholipid antibodies (aPL) at the time of transplantation is an important risk factor for early renal allograft failure. Sera were tested for IgG, IgM and IgA to CL, PS, PE and PC. Haemodialysis patients had a significantly higher incidence of aPL compared to patients who did not receive haemodialysis (P = 0.0171). aPL-positive ESRD patients on peritoneal dialysis (CAPD) or who had never received haemodialysis were at maximal risk; 100% failure (P = 0.0022). aPL-positive patients receiving haemodialysis were not at such risk. Biopsy findings from the failed kidneys show abundant fibrin deposition in the microvasculature. Serial blood samples from transplanted patients showed aPL titres to decrease immediately after transplant and increase after removal of the failed graft, indicating that aPL specifically target the allografts. To confirm this, we were able to isolate aPL from a failed graft after transplant nephrectomy. Ninety-seven per cent of the aPL-positive patients' historic pre-transplant serum samples demonstrated the presence of the same aPL specificity detected in the final crossmatch sera. The exposure to heparin during haemodialysis suggested to us that heparin reduces the risk of clotting in aPL positive transplant candidates. To lessen the risk of graft loss in aPL positive kidney transplant patients (including CAPD), subcutaneous heparin was administered peri- and post-operatively. To date, none of the heparin-treated aPL-positive transplanted patients suffered an early graft loss. Further, they experienced fewer rejection episodes requiring biopsy and thus are prescribed less steroid therapy than patients not treated with heparin.

Frequency and specificities of antiphospholipid antibodies (aPL) in volunteer blood donors

In the State of Indiana, blood donors are screened by a written questionnaire prior to donation to identify potential exposures to infectious diseases and to assess medications. The potential donor is not asked about aPL-related events. Animal experiments have shown, however, that passive transfer of aPL can produce aPL-associated pathology in the recipient. We determined the incidence of antiphospholipid antibodies (aPL) in 775 volunteer blood donors in Indiana. Tubing segments containing 2 ml of anticoagulated blood were obtained from donor units. The average donor age was 43 years (range 17-82); 45% were female. Our in-house aPL ELISA tested for IgG, IgA and IgM to cardiolipin (aCL), phosphatidylserine (aPS), phosphatidylethanolamine (aPE) and phosphatidylcholine (aPC). The plasmas were tested with and without supplemental phospholipid (PL)-binding plasma proteins from adult bovine plasma (ABP). A total of 24 tests were performed for each donor. Normal ranges were determined for 98% of the donors by calculating multiples of the means (MoM) of OD values for each antigen-isotype combination. No decimals were used, all MoMs were rounded up to the next whole number. An additional two MoMs were added to the calculated cutoff values to eliminate borderline positive values. Results revealed that 63 (8.1 %) donors had positive findings for one or more aPL. The relatively high number of aPL-positive individuals reflects the observation that different donors were often in the highest 2% of each antigen-isotype combination tested. The aPL specificities, isotypes, and PL-binding protein dependence are summarized in this report.

The combination of different antiphospholipid antibody subgroups in the sera of patients with autoimmune diseases is a strong predictor for thrombosisA retrospektive study from a single center

[corrected] To determine the distribution of different antiphospholipid antibodies (APL-Ab) and their association with thrombosis in patients with autoimmune diseases. Clinical data and laboratory features of 30 patients with different autoimmune diseases with positive APL-Ab were retrospectively studied for a period of more than two years. Anti-cardiolipin (aCL), anti-phosphatidylserine (aPS) and anti-beta2-glycoprotein I (abeta2-GPI) antibodies were determined by ELISA. Autoantibodies that target only PS were detected in 53.3% (n = 16) patients, aCL antibodies only were found in one patient (3,3%). In 43.3% (n = 13), aPS were associated with elevated levels of aCL and/or abeta2-GPI antibodies. No thrombotic event occurred in patients with aPS antibodies only compared to 6 patients from the group with different APL-Ab during 808 +/- 92 days of observation. The combination of different antiphospholipid antibody subgroups seems to be a predictor for thrombosis. The presence of aPS antibodies without additional aCL or abeta2-GPI is not associated with thrombosis. The measurement of the APL specificities in addition to the aCL antibodies may be important to develop predictive markers for the risk to develop thrombotic events.

The combination of different antiphospholipid antibody subgroups in the sera of patients with autoimmune diseases is a strong predictor for thrombosis: A retrospektive study from a single center

Objective: To determine the distribution of different antiphospholipid antibodies (APL-Ab) and their association with thrombosis in patients with autoimmune diseases. Methods: Clinical data and laboratory features of 30 patients with different autoimmune diseases with positive APL-Ab were retrospectively studied for a period of more than two years. Anti-cardiolipin (aCL), anti-phosphatidylserine (aPS) and anti-β2-glycoprotein I (aβ2-GPI) antibodies were determined by ELISA. Results: Autoantibodies that target only PS were detected in 53.3% (n=16) patients, aCL antibodies only were found in one patient (3,3%). In 43.3% (n=13), aPS were associated with elevated levels of aCL and/or aβ2-GPI antibodies. No thrombotic event occurred in patients with aPS antibodies only compared to 6 patients from the group with different APL-Ab during 808±92 days of observation. Conclusion: The combination of different antiphospholipid antibody subgroups seems to be a predictor for thrombosis. The presence of aPS antibodies without additional aCL or aβ2-GPI is not associated with thrombosis. The measurement of the APL specificities in addition to the aCL antibodies may be important to develop predictive markers for the risk to develop thrombotic events.

Spectrum of antiphospholipid antibodies (aPL) in patients with cerebrovascular disease

Background: The association of stroke and antiphospholipid antibodies (aPL) other than anticardiolipin antibodies (aCL) is not well documented. Objective: To report the distribution of aCL, antiphosphatidylethanolamine (aPE), and antiphosphatidylserine (aPS) aPL among patients with symptomatic cerebrovascular disease evaluated by our Stroke Service at Indiana University Hospital from January 1997 to November 1999. Methods: We retrospectively reviewed medical records from 1997 to 1999 at Indiana University Hospital for all patients with symptomatic cerebrovascular disease using the International Statistical Classification of Diseases, 9th Revision, (ICD-9) codes. We identified patients with elevated titers of aPL. Sera from these patients were obtained within the first 30 days of the index event. We included only those patients for whom the serum samples were tested in a single laboratory by an in-house enzyme-linked immunosorbent assay (ELISA) for immunoglobulin G (IgG) immunoglobulin A (IgA) and immunoglobulin M (IgM) aCL, aPE, and aPS. We examined the clinical presentation, stroke risk factors, associated rheumatologic disorders, and distribution of aPL specificity and isotype. Results: Thirty-four of 185 patients, 26 women (76%), with a mean age of 46 years, and 8 men (24%) with a mean age of 46 years, had aPL. Nine patients had transient ischemic attacks (TIA), 25 suffered strokes, 23 had ischemic infarcts, and 2 had hemorrhagic infarcts (1 had a superior sagittal sinus thrombosis with bilateral hemispheric hemorrhagic infarcts, and one had bilateral hemorrhagic infarcts associated with systemic lupus erythematosus [SLE]). Six patients had SLE. The most common stroke risk factors were cigarette smoking (38%) and arterial hypertension (26%). Approximately two thirds (60%) of patients had a single positive aPL finding: aPE in 35%, aCL in 18%, and aPS in 6%. Multiple specificities were seen in 40%. IgA was the only aPL antibody isotype detected in 26% of the patients, IgG was the lone isotype in 24%, and IgM alone in 12%. Multiple aPL isotypes were detected in 38% of patients. Five patients (15%) presented with aPE IgA as the exclusive aPL. Conclusion: In our series, aPE was the most frequent finding in stroke patients who were suspected to have an associated aPL syndrome. These specific types of aPL may be present relatively often in stroke patients and are often not assessed. Further studies are needed to determine how specific these aPL are in stroke versus other acute illnesses and versus healthy controls, and how these aPL are associated with stroke risk. Copyright © 2001 by National Stroke Association

ANTIPHOSPHOLIPID (HUGHES) SYNDROME IN SYSTEMIC LUPUS ERYTHEMATOSUS

APS is found in 20% to 35% of patients with SLE. PAPS and secondary APS have similar features and aPL specificities. The clinical course of the secondary syndrome is independent of the activity and severity of lupus, but the presence of APS worsens the prognosis of patients with lupus. Some features of SLE may result from thrombosis in patients with APS; thus, these patients require anticoagulation rather than corticosteroids. Novel preliminary classification criteria for APS were formulated during a postconference workshop held in Sapporo, Japan, following the Eight International Symposium on Antiphospholipid Antibodies. Treatment of APS remains empirical because of limited controlled prospective data. There is strong evidence that patients with aPL-associated thrombosis are subject to recurrences and require prophylactic therapy. APS is a treatable cause of recurrent fetal loss in women with SLE. The treatment of choice is anticoagulation with heparin, either standard unfractionated heparin or LMWH. One of the main reasons for the improving outcomes in APS pregnancies is closer obstetric surveillance.