Antibodies to age‐β2glycoprotein I in patients with anti‐phospholipid antibody syndrome

Anti‐phospholipid antibody syndrome (APS) is a systemic autoimmune disease characterized clinically by arterial and/or venous thromboses, recurrent abortions or fetal loss and serologically by the presence of ‘anti‐phospholipid antibodies’ (aPL). The main target antigen of the antibodies is β₂glycoprotein I (β₂GPI). Post‐translational oxidative modifications of the protein have been widely described. In this study we aimed to analyse sera reactivity to glucose‐modified β₂GPI (G‐β₂GPI). Sera collected from 43 patients with APS [15 primary APS (PAPS) and 28 APS associated with systemic lupus erythematosus (SLE) (SAPS)], 30 with SLE, 30 with rheumatoid arthritis (RA) and 40 healthy subjects were analysed by an enzyme‐linked immunosorbent assay (ELISA) using a G‐β₂GPI. Nine of 15 consecutive PAPS out‐patients (60%) and 16 of 28 SAPS (57.1%) showed serum antibodies [immunoglobulin (Ig)G class] against G‐β₂GPI (anti‐G‐β₂GPI) by ELISA. The occurrence of anti‐G‐β₂GPI was significantly higher in APS patients compared to patients suffering from SLE. No RA patients or control healthy subjects resulted positive for anti‐G‐β₂GPI. Of note, aG‐β₂GPI prompted to identify some APS patients (four PAPS and seven SAPS), who were negative in the classical anti‐β₂GPI test. Moreover, in APS patients, anti‐G‐β₂GPI titre was associated significantly with venous thrombosis and seizure in APS patients. This study demonstrates that G‐β₂GPI is a target antigen of humoral immune response in patients with APS, suggesting that β₂GPI glycation products may contain additional epitopes for anti‐β₂GPI reactivity. Searching for these antibodies may be useful for evaluating the risk of clinical manifestations.     

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.     

APhL antibody ELISA as an alternative to anticardiolipin test for the diagnosis of antiphospholipid syndrome

Background

Persistent levels of antiphospholipid (aPL) antibodies [lupus anticoagulant (LA), anticardiolipin (aCL), anti-beta 2 glycoprotein I (aβ₂GPI) IgG and/or IgM] in association with clinical features of thrombosis and/or pregnancy associated morbidity are indicative of antiphospholipid syndrome (APS). Of the aPL antibodies, aCL is the most sensitive for APS, however, their lack of specificity constitute a laboratory and clinical challenge. IgG/IgM antibodies directed against APhL (a mixture of phospholipids) has been reported to predict APS more reliably than aCL tests. The main objective of this study was to evaluate the performance characteristics of the APhL IgG/IgM ELISA, relative to the aCL and aβ₂GPI tests.

Methods

Sixteen (16) clinically confirmed APS and 85 previously tested serum (PTS) samples for aCL and aβ₂GPI IgG/IgM antibodies were evaluated with the APhL IgG/IgM ELISA. Clinical specificity was determined in 100 serum samples (50 healthy and 50 infectious disease controls [parvo- and syphilis-IgG/IgM positive]).

Results

The IgG antibody prevalence for aCL and APhL in the APS and PST groups was comparable with marginal differences in clinical specificities. In contrast to the aCL IgM ELISA, the APhL test showed improved clinical specificities (72% aCL vs 94% APhL in the healthy controls; 38% aCL vs 78% APhL in the infectious disease controls) with implications for increased reliability in the diagnosis of APS. The overall agreement of the APhL with the aCL or aβ₂GPI for the IgG tests was 89% and 85% respectively, and that of the APhL IgM to the aCL or aβ₂GPI IgM tests was 72% and 86% respectively.

Conclusion

Routine use of the APhL IgG/IgM ELISA may substantially reduce the high number of false positives associated with the aCL test without loss in sensitivity for APS.     

Laboratory evaluation of anti-phospholipid syndrome: a preliminary prospective study of phosphatidylserine/prothrombin antibodies in an at-risk patient cohort

Immunoglobulin (Ig)G/IgM autoantibodies to phosphatidylserine/prothrombin (aPS/PT) were evaluated individually and in combination with criteria anti-phospholipid (aPL) tests in a prospectively ascertained cohort of patients at risk for anti-phospholipid syndrome (APS). One hundred and sixty (160) consecutive requests for lupus anti-coagulant (LAC) from the University of Utah Health Sciences Center were identified during 8 weeks. Of these, 104 unique patients had additional requests for cardiolipin (aCL) and/or beta2 glycoprotein I (aβ₂GPI) IgG and/or IgM; samples were retained and analysed for aPS/PT, aCL and/or aβ₂GPI IgG and IgM antibodies. Following testing, a comprehensive chart review was performed and patients categorized according to their clinical diagnosis. Individual and combined sensitivities, specificities, odd ratios (OR), diagnostic accuracy for specific tests or combinations by receiver operating characteristic (ROC), area under the curve (AUC) analyses and correlations between test results were determined. The sensitivities of aPS/PT IgG/IgM (54·6/45·5%) were lower than LAC (81·8%) but higher relative to aCL IgG/IgM (27·3/0%) or aβ₂GPI IgG/IgM (27·3/0%). The best correlation between LAC and any aPL test was observed with aPS/PT (P = 0·002). There was no significant difference in the diagnostic accuracies for any panel with LAC: LAC/aβ₂GPI IgG/aCL IgG [AUC 0·979, OR 475·4, 95% confidence interval (CI) 23·1–9056·5, P = 0·0001 and LAC/aβ₂GPI IgG/aPS/PT IgG or LAC/aPS/PT IgG/aCL IgG (AUC 0·962, OR 265·3, 14·2–4958·2, P = 0·0001). The high correlation between LAC and aPS/PT IgG/IgM in this preliminary study suggest that this marker may be useful in the evaluation of APS. More studies to determine the optimal aPL antibody tests combination are needed.     

Persistence of antiphospholipid antibodies over time and its association with recurrence of clinical manifestations: A longitudinal study from a single centre

PurposeTo analyze the antiphospholipid antibody (aPL) persistence over time in patients with antiphospholipid syndrome (APS) and its association with clinical recurrence and to identify predictors of aPL persistence over time.Patients and methods200 patients with a diagnosis of APS and at least three follow-up aPL determinations were included. Persistent aPL profile was defined as the presence of lupus anticoagulant (LAC) and/or IgG/IgM anticardiolipin (aCL) and/or IgG/IgM anti-β2 glycoprotein-I (aβ2GPI) (> 99th percentile) antibodies in at least 66% of follow-up measurements. Multilevel mixed-effect generalized linear models with logit link were used.Results112 (56%) patients maintained persistent aPL profiles over time, while 88 (44%) were transient. Median follow-up time was 172.5 months. Follow-up time did not affect the odds of aPL persistence in multivariate analysis (p = 1.00). Baseline triple aPL positivity [OR 78 (95%CI 16.9–359.7, p < 0.001)] and double aPL positivity [OR = 7.6 (95%CI 3.7–15.7, p < 0.001)] correlated with persistent aPLs over time, while isolated LAC [OR = 0.26 (95% CI 0.08–0.49, p = 0.002)] or isolated IgG/IgM aCL [OR = 0.20 (95% CI 0.11–0.59, p = 0.004)] positivity, were predictors of transient aPL profile. Patients with persistent aPLs had higher rate of clinical recurrence in comparison to patients with transient aPLs [OR = 2.48 (95%CI 1.34–4.58, p = 0.003)].ConclusionsMore than half of patients with baseline medium-high titer aPL positivity had persistent positive aPLs over time. Patients with persistent aPLs were more prone to present recurrence of clinical manifestations. Multiple aPL positivity increased the odds of a persistent aPL profile over time, while isolated LAC and aCL positivity decreased it.     

Influence of statin therapy on antiphospholipid antibodies and endothelial dysfunction in young patients with coronary artery disease and systemic lupus erythematosus

IntroductionAntiphospholipid antibodies (aPL) affect atherogenesis and may cause thromboembolism in systemic lupus erythematosus (SLE) and coronary artery disease (CAD). Intensive treatment with statins may reduce inflammation and decrease the number of thrombotic events. That may explain the beneficial effect of statin therapy in SLE and CAD. This study was established to investigate the influence of statin treatment on aPL antibody levels and selected endothelial dysfunction markers in CAD and SLE patients.Material and methodsFifty-eight patients – 40 after coronary revascularization (age 38.9 (27–46), 35 males) and 18 with clinically stable SLE (age 38.8 (18–62), 1 male) – were enrolled in the study. In both groups intensive atorvastatin treatment was administered. At baseline and after 1 year of follow-up serology tests were performed: anticardiolipin antibodies (aCL), anti-β2 glycoprotein I (aβ2GPI), lupus anticoagulant (LA), C-reactive protein (CRP), soluble form of intracellular adhesion molecule-1 (sICAM-1), vWF:Ag.ResultsCoronary artery disease patients in 1 year follow-up revealed a decrease of aβ2GPI IgG and CRP. There was a significant increase in aCL IgG, sICAM-1 and vWF:Ag. In SLE patients aPL levels showed no significant reduction after treatment.ConclusionsIn clinically stable patients IgM and IgG class aβ2GPI levels are higher in CAD than in SLE, whereas IgG class aCL levels are lower. Statin treatment decreases the CRP level in both SLE and CAD patients, while decreasing the aβ2GPI IgG level only in CAD patients.     

Relationship between natural and infection‐induced antibodies in systemic autoimmune diseases (SAD): SLE,SSc and RA

Infection or vaccine‐induced T cell‐dependent immune response and the subsequent high‐affinity neutralizing antibody production have been extensively studied, while the connection between natural autoantibodies (nAAbs) and disease‐specific antibodies has not been thoroughly investigated. Our goal was to find the relationship between immunoglobulin (Ig)M and IgG isotype nAAbs and infection or vaccine‐induced and disease‐related autoantibody levels in systemic autoimmune diseases (SAD). A previously described indirect enzyme‐linked immunosorbent assay (ELISA) test was used for detection of IgM/IgG nAAbs against citrate synthase (anti‐CS) and F4 fragment (anti‐F4) of DNA topoisomerase I in 374 SAD samples, with a special focus on systemic lupus erythematosus (SLE) (n = 92), rheumatoid arthritis (n = 73) and systemic sclerosis (n = 157) disease groups. Anti‐measles IgG and anti‐dsDNA IgG/IgM autoantibodies were measured using commercial and in‐house indirect ELISA tests. In all SAD groups the anti‐measles IgG‐seropositive cases showed significantly higher anti‐CS IgG titers (P = 0·011). In anti‐dsDNA IgG‐positive SLE patients, we detected significantly higher levels of anti‐CS and anti‐F4 IgG nAAbs (P = 0·001 and < 0·001, respectively). Additionally, we found increased levels of IgM isotypes of anti‐CS and anti‐F4 nAAbs in anti‐dsDNA IgM‐positive SLE patients (P = 0·002 and 0·016, respectively). The association between IgG isotypes of pathogen‐ or autoimmune disease‐related antibodies and the IgG nAAbs may underscore the immune response‐inducible nature of the diseases investigated. The relationship between protective anti‐dsDNA IgM and the IgM isotype of anti‐F4 and anti‐CS may provide immunoserological evidence for the beneficial roles of nAAbs in SLE patients.     

Associations of B cell‐activating factor (BAFF) and anti‐BAFF autoantibodies with disease activity in multi‐ethnic Asian systemic lupus erythematosus patients in Singapore

To measure the levels of B cell‐activating factor (BAFF) and endogenous anti‐BAFF autoantibodies in a cohort of multi‐ethnic Asian systemic lupus erythematosus (SLE) patients in Singapore, to determine their correlation with disease activity. Serum samples from 121 SLE patients and 24 age‐ and sex‐matched healthy controls were assayed for BAFF and anti‐BAFF immunoglobulin (Ig)G antibody levels by enzyme‐linked immunosorbent assay (ELISA). The lowest reliable detection limit for anti‐BAFF‐IgG antibody levels was defined as 2 standard deviations (s.d.) from blank. Correlation of serum BAFF and anti‐BAFF IgG levels with disease activity [scored by SLE Activity Measure revised (SLAM‐R)], and disease manifestations were determined in these 121 patients. SLE patients had elevated BAFF levels compared to controls; mean 820 ± 40 pg/ml and 152 pg ± 45/ml, respectively [mean ± standard error of the mean (s.e.m.), P < 0·01], which were correlated positively with anti‐dsDNA antibody levels (r = 0·253, P < 0·03), and SLAM‐R scores (r = 0·627, P < 0·01). In addition, SLE patients had significantly higher levels of anti‐BAFF IgG, which were correlated negatively with disease activity (r = –0·436, P < 0·01), levels of anti‐dsDNA antibody (r = –0·347, P < 0·02) and BAFF (r = –0·459, P < 0·01). The majority of patients in this multi‐ethnic Asian SLE cohort had elevated levels of BAFF and anti‐BAFF antibodies. Anti‐BAFF autoantibody levels correlated negatively with clinical disease activity, anti‐dsDNA and BAFF levels, suggesting that they may be disease‐modifying. Our results provide further information about the complexity of BAFF pathophysiology in different SLE disease populations and phenotypes, and suggest that studies of the influence of anti‐cytokine antibodies in different SLE populations will be required when selecting patients for trials using targeted anti‐cytokine therapies.     

Autoantibody profiling of patients with antiphospholipid syndrome using an automated multiplexed immunoassay system

The antiphospholipid syndrome (APS) is an autoimmune disease defined by the co-occurrence of clinical and serological symptoms [presence of at least one of the antiphospholipid autoantibodies (aPL), such as anti-cardiolipin (aCL) IgG/IgM and anti-β2glycoprotein I (aβ2GPI) IgG/IgM]. The measurement of these autoantibodies constitutes the first-line approach for the diagnosis of APS. Recently the advent of multiplex proteomic technologies seems to be an optimal solution for the parallel detection of autoantibodies (IgG, IgA, IgM) related to APS. The BioPlex 2200 is an automated commercial platform based on the multi-analyte profiling technology that allows the detection of different types of autoantibodies, particularly ANA, ENA, dsDNA, PR3, MPO, GBM. We performed firstly a study to evaluate the diagnostic accuracy of this analytical system in a group of APS patients. The BioPlex system showed a good diagnostic accuracy for all test evaluated, very similar to that of the other established commercial singleplex immunoassays. In our study, the simultaneous detection of aCL and aβ2GPI of IgA isotype in addition to IgG and IgM isotypes did not increase the diagnostic sensitivity for APS. The good diagnostic accuracy, the high level of automation, and the high throughput make this multiplex platform a very useful and practical tool for the laboratory diagnosis of aPL in daily practice.     

Detection of antiphospholipid antibodies by automated chemiluminescence assay

The laboratory diagnosis of antiphospholipid antibody syndrome (APS) requires the demonstration of antiphospholipid antibodies (aPL) by lupus anticoagulant (LAC) measured through coagulation assays, anticardiolipin IgG or IgM antibodies (aCL) and/or anti-β2-glycoprotein I IgG or IgM antibodies (anti-β2-GPI), usually detected by ELISA. In this study we tested aCL by a new automated system using the chemiluminescence principle. Our results showed that, while almost all the sera from APS patients, positive for IgG aCL and anti-β2-GPI by ELISA, were also positive for IgG aCl by chemiluminescence, only 30.13% of patients without clinical manifestations of APS, but positive for aCL and persistently negative for anti-β2-GPI (by ELISA) and LA, confirmed the positive test by chemiluminescence. This difference was highly significant (p<0.0001). Interestingly, this test also prompted to identify 20% of patients positive for LA, but persistently negative for both aCL and anti-β2-GPI IgG (ELISA). Thus, the new technology of automated chemiluminescence assay for measuring aPL may represent an useful tool to identify "true" APS patients.     

The Investigation on the Value of Repeat and Combination Test of ACA and Anti‐β2‐GPI Antibody in Women with Recurrent Spontaneous Abortion

Problem In order to investigate the value of anticardiolipin antibodies (ACA) and anti‐β₂‐GPI antibodies detection in screening autoimmune type recurrent spontaneous abortion and its clinic application in antiphospholipid syndrome diagnosis, we adopt repeat combined ACA and anti‐β₂‐GPI antibodies detection in this study. Method of study Sera were collected from patients and work‐up was done for detection of ACA and anti‐β₂‐GPI antibodies by enzyme‐linked immunosorbent assay (ELISA). The work‐up was done for detection of antibodies once in every 6 weeks for 14 times consecutively. Results The repeated and combined detection of ACA and anti‐β₂‐GPI antibodies detection could raise the positivity rate up to 21.8% (P < 0.05) in comparison with positive for ACA alone (14.1%), positive for anti‐β₂‐GPI alone (3.1%), and concurrently positive for both ACA and anti‐β₂‐GPI antibodies (4.6%). In 91 confirmed positive antiphospholipid antibodies (APA) patients, with more frequent screening for ACA and anti‐β₂‐GPI antibodies, more patients with APA were found. The positive rate of five and more screenings was over 81.32%, which was statistically significant (P < 0.05), in comparison with that of four or less screenings (68.13%). Conclusion Our data implied that it would be appropriate to take over five or more screenings of combined ACA and anti‐β₂‐GPI antibodies detection in suspect patients to facilitate the positive diagnostic rate for autoimmune type RSA.     

Antiphospholipid Antibodies are Associated with Low Levels of Complement C3 and C4 in Patients with Systemic Lupus Erythematosus

Complement activation and low complement levels are common in systemic lupus erythematosus (SLE). Antiphospholipid antibodies (aPL) are found in about 30‐40% of patients with SLE. This study aimed to investigate the association between aPL and complement levels in patients with SLE. Serum samples were collected from 269 patients with SLE enrolled in the Norwegian Systemic Connective Tissue and Vasculitis Registry (NOSVAR) during 2003‐2009, and from 353 controls. All samples were analysed for anti‐β2 glycoprotein 1 (anti‐β2GP1) and anticardiolipin antibodies (aCL), C‐reactive protein (CRP) and complement components C3 and C4. Median CRP level was significantly higher in cases than in controls (2.06 versus 0.90 mg/l; P < 0.0001). No significant difference in CRP was found between SLE patients with or without aPL (2.09 versus 1.89; P = 0.665). Median C3 levels were similar in cases (1.03 g/l) and controls (1.00 g/l), whereas median C4 levels were 0.16 g/l in cases versus. 0.19 in controls (P < 0.0001). However, aPL‐positive SLE patients had significantly lower median C3 levels (0.92 versus. 1.07 g/l; P = 0.001) and C4 levels (0.11 versus 0.16 g/l; P < 0.0001) compared to aPL‐negative patients. Lower C3 and C4 values in aPL‐positive SLE patients may reflect a higher consumption of C3 and C4 due to more pronounced complement activation in aPL‐positive SLE patients compared to SLE patients without aPL.     

Clinical Thrombotic Manifestations in SLE Patients With and Without Antiphospholipid Antibodies: A 5-year Follow-up

Objective To analyze the association of antiphospholipid antibodies (aPL) with the development of clinical thrombotic manifestations and to characterize the efficacy of anti-thrombotic therapies used. Methods 272 systemic lupus erythematosus (SLE) patients participated in the study. Patient files and a cumulative database were used to collect patients’ medical histories. Anti-cardiolipin (aCL), anti-beta2-glycoprotein I (aβ2GPI) antibodies, and lupus anticoagulant (LAC) were measured according to international recommendations. New thrombotic events were registered during follow-up. Results The patients were prospectively studied for 5 years, of whom 107 were aPL negative (aPL− group). Criteria for antiphospholipid syndrome (APS) were fulfilled by 84 of 165 aPL-positive patients (APS+ group) indicating that SLE patients with aPL have around 50% risk to develop thrombotic complications. The aPL+ group (n = 81) consisted of aPL+ but APS− patients. LAC was the most common aPL (n = 27, 32.1%) in patients with APS. The cumulative presence of aPL further increased the prevalence of thrombotic events. During the follow-up period, aPL developed in 8 of 107 patients (7.5%) from the aPL− group, of whom 3 (2.8%) presented with thrombotic complications. Other types of aPL developed in 7 of 165 (4.2%) aPL+ patients within 5 years. New thrombotic events occurred in 3.7% of aPL+ (n = 3) and 8.3% (n = 7) of the APS group. During follow-up, 52 of 81 aPL+ patients received primary prophylaxis, and 1 (1.9%) had transient ischemic attack (TIA). In the non-treatment group, 2 (6.9%) had stroke. Seventy-nine of 84 of the APS patients received secondary prophylaxis, and myocardial infarction occurred in 2 patients (on cumarine therapy maintaining an international normalized ratio around 2.5–3.0), and 5 suffered a stroke/TIA (1 on aspirin and 4 on aspirin + cumarine). Conclusion The findings emphasize the importance of determining both aCL and aβ2GPI antibodies and LAC in SLE patients and the need for adequate anticoagulant therapy.     

Toll-like receptor (TLR)-4 mediates anti-β2GPI/β2GPI-induced tissue factor expression in THP-1 cells

Our previous study demonstrated that annexin A2 (ANX2) on cell surface could function as a mediator and stimulate tissue factor (TF) expression of monocytes by anti‐β₂‐glycoprotein I/β₂‐glycoprotein I complex (anti‐β₂GPI/β₂GPI). However, ANX2 is not a transmembrane protein and lacks the intracellular signal transduction pathway. Growing evidence suggests that Toll‐like receptor 4 (TLR‐4) might act as an ‘adaptor’ for intracellular signal transduction in anti‐β₂GPI/β₂GPI‐induced TF expressing cells. In the current study, we investigated the roles of TLR‐4 and its related molecules, myeloid differentiation protein 2 (MD‐2) and myeloid differentiation factor 88 (MyD88), in anti‐β₂GPI/β₂GPI‐induced TF expressing human monocytic‐derived THP‐1 (human acute monocytic leukaemia) cells. The relationship of TLR‐4 and ANX2 in this process was also explored. Along with TF, expression of TLR‐4, MD‐2 and MyD88 in THP‐1 cells increased significantly when treated by anti‐β₂GPI (10 µg/ml)/β₂GPI (100 µg/ml) complex. The addition of paclitaxel, which competes with the MD‐2 ligand, could inhibit the effects of anti‐β₂GPI/β₂GPI on TLR‐4, MD‐2, MyD88 and TF expression. Both ANX2 and TLR‐4 in THP‐1 cell lysates could bind to β₂GPI that had been conjugated to a column (β₂GPI‐Affi‐Gel). Furthermore, TLR‐4, MD‐2, MyD88 and TF expression was remarkably diminished in THP‐1 cells infected with ANX2‐specific RNA interference (RNAi) lentivirus (LV‐RNAi‐ANX2), in spite of treatment with a similar concentration of anti‐β₂GPI/β₂GPI complex. These results indicate that TLR‐4 and its signal transduction pathway contribute to anti‐β₂GPI/β₂GPI‐induced TF expression in THP‐1 cells, and the effects of TLR‐4 with ANX2 are tightly co‐operative.     

Anti-cardiolipin and anti-beta 2-glycoprotein I antibodies in celiac disease

Aims

To determine the frequency of anti-cardiolipin (aCL) and anti-β2-glycoprotein I antibodies (aβ2GPI) in celiac disease (CD) patients.

Patients and methods

Sixty-three untreated CD patients and 40 healthy blood donors (HBD) were studied. IgG, IgA and IgM aCL and aβ2GPI were detected by Elisa.

Results

The frequency of antiphospholipid antibodies (aPL) (aCL and/or aβ2GPI) was significantly higher in CD patients (12 out of 63) than in HBD (two out of 40) (19% vs 5%, P = 0.04). Six CD patients out of 63 (9.5%) and one HBD out of 40 (2.5%) had aCL. Ten CD patients (15.9%) and two HBD (5%) had aβ2GPI. Only aβ2GPI-IgA was significantly more frequent in CD patients than in HBD (14.3% vs 2.5%, P = 0.048). In CD patients, aβ2GPI-IgA (nine out of 63) was significantly more frequent (14.3%) than aβ2GPI-IgG (1.6%) and IgM (1.6%) (P = 0.008). In CD patients, the frequency of aCL-IgA and IgM was 6.3% (four out of 63) and aCL-IgG were not detected. Simultaneous presence of positive antibodies was found in four CD patients: one patient had four aPL, one had three aPL and two had two aPL. The four patients who had aCL-IgA had also aβ2GPI-IgA and three of them had a titer higher than 50 units. Among nine patients with aβ2GPI-IgA, four had a titer higher than 100 units. The highest titers were found in adults.

Conclusions

aPL and particularly aβ2GPI-IgA are frequent in CD. The significance of these antibodies has to be determined.     

Anti-phospholipid antibodies following vaccination with recombinant hepatitis B vaccine

This study was undertaken to evaluate the possible role of hepatitis B recombinant vaccine inducing the synthesis of IgG and IgM anti-cardiolipin antibodies (aCL), antibodies against beta(2)GPI (anti-beta(2)GPI), lupus anti-coagulant (LA), anti-nuclear antibodies and antibodies against extractable nuclear antigens (anti-ENA). The study population consisted of 85 healthy students (63 female, 22 male; mean age 20.8 years), vaccinated with three doses of recombinant DNA hepatitis B vaccine. One month after vaccination with the first dose of hepatitis B vaccine a minority of vaccinated individuals showed changes in IgG or IgM aCL or anti-beta(2)GPI or LA activity (P < 0.001). Among subjects in whom changes of IgG anti-beta(2)GPI were observed, a significantly higher number of increased (8/85) than decreased (2/85) values were found (P < 0.01). Analyses of paired data showed that differences in aCL or anti-beta(2)GPI levels before vaccination or 1 month later did not reach statistical significance. In two people aCL transitorily reached medium positivity after the first dose of hepatitis B vaccine with a drop 5 months later. Similar evident anti-beta(2)GPI fluctuation was also observed in one person. Another participant was initially low positive for IgG anti-beta2GPI and the levels were increasing after vaccination. Two participants became positive for anti-nuclear antibodies during 6 months' follow-up. There were no sex-dependent differences in tested antibodies observed and no associations between levels of aPL and levels of anti-HBV antibodies. We conclude that HBV can induce aPL, although rarely. In genetically susceptible individuals or together with some other triggers such combination might confer the risk of developing a continuous autoimmune response in an individual.     

Which are the best biological markers of the antiphospholipid syndrome?

The diagnosis of antiphospholipid syndrome (APS) requires the presence of both clinical and biological features. Due to the heterogeneity of anti-phospholipid antibodies (aPL) the laboratory approach for their detection includes clotting-based tests for lupus anticoagulant (LA) as well as solid-phase assays for anticardiolipin antibodies (aCL). In addition, as it has been shown that autoimmune aPL recognize epitopes on phospholipid (PL)-binding plasma proteins, assays detecting antibodies to beta 2-glycoprotein I (beta 2-GPI) or prothrombin have been developed. The association between venous or arterial thrombosis and recurrent fetal loss with the presence of conventional aPL (LA and/or aCL) has been confirmed by many studies. The LA and IgG aCL at moderate/high titre seem to exhibit the strongest association with clinical manifestations of the APS. Several reports indicate that LA is less sensitive but more specific than aCL for the APS. Assays against PLs other than CL as well as the use of mixtures of PLs have been proposed to improve the detection of APS-related aPL. Concerning antibodies to PL-binding proteins (detected in the absence of PLs), there is evidence that anti-beta 2-GPI are closely associated with thrombosis and other clinical features of the APS. Moreover, these antibodies may be more specific in the recognition of the APS and in some cases may be present in the absence of aPL detected by standard tests. Many issues are still under debate and are discussed in this review, such as the problems of standardization of anti-beta 2-GPI assays, detection of the IgA isotype of aCL and anti-beta 2-GPI, the coagulation profiles of LA in the recognition of the thrombotic risk and the association of particular markers with subsets of patients with APS.     

Anti-beta 2-glycoprotein I and antiphosphatidylserine antibodies are predictors of arterial thrombosis in patients with antiphospholipid syndrome

The predictive value (PV) and association of 4 antiphospholipid antibodies with clinical manifestations of the antiphospholipid syndrome (APS) were evaluated in 90 patients with systemic lupus erythematosus (SLE) and 100 with APS. Patients with APS were classified into arterial thrombosis, venous thrombosis, and pregnancy morbidity subgroups. IgG, IgM, and IgA anticardiolipin (aCL), antiphosphatidylserine (aPS), anti-beta 2-glycoprotein I (anti-B2GPI), and antiprothrombin (aPT) antibodies were determined by enzyme-linked immunosorbent assay. Individually, anti-B2GPI and aPS antibodies had the strongest PV for APS (86.4%-94.1%; P < .001) in patients with SLE. The PV for APS reached 100% when 2 or more antibodies were present. Similarly, anti-B2GPI and aPS antibodies had a stronger PV and association for arterial thrombosis (87%-95%; P < .001) compared with venous thrombosis (80%-92%; P = .01). Weak PV and association with pregnancy morbidity were seen with all antibodies. These results suggest an important pathogenic role of anti-B2GPI antibodies in arterial thrombosis. In addition, anti-B2GPI and aPS antibodies seem to provide the best diagnostic value for the laboratory assessment of APS.     

Laboratory evaluation of the antiphospholipid syndrome

The antiphospholipid syndrome (APS) was first described in 1986. The original association of this hypercoagulable state with anticardiolipin antibodies (aCL) resulted from the synthesis of evidence stemming from laboratory findings in systemic lupus erythematosus (SLE), ie, the frequent occurrence of false-positive VDRL tests and the paradoxical observation of the so-called "lupus anticoagulant" (LA), an increase in phospholipid (PL)-dependent clotting times. By the early 1990s, it was clear that a co-factor was involved in the reaction of antibodies to PL (aPL) in SLE patients with secondary APS and that this was a hitherto-obscure protein, beta-2 glycoprotein I (beta2GPI). In the intervening years, it has been established that beta2GPI and other PL-binding proteins such as prothrombin (PT) are relevant antigens in APS and assays for these antigens have been developed, standardized, and applied to subjects with both primary and secondary APS. Measurement and confirmation of LA activity is based on a stepwise approach and should follow the recommendations of the International Society of Thrombosis and Haemostasis. Although antibodies to various PL-binding proteins have been suggested as diagnostic targets for APS, the current (2006) consensus guidelines recognize only LA, aCL, and anti-beta2GPI for the classification of APS.