Elevated IgA antiphospholipid antibodies in healthy pregnant women in Sudan but not Sweden, without corresponding increase in IgA anti-β2 glycoprotein I domain 1 antibodies

Combined detection of anticardiolipin and anti-β2-glycoprotein 1 antibodies may predict pregnancy outcome

Antiphospholipid syndrome (APS) is a typical non-inflammatory autoimmune disease that is common in young women. It is characterized by the presence of the anti-cardiolipin antibody (ACA) and anti-β2 glycoprotein 1 (anti-β2-GP1) antibody and is associated with a high risk of arteriovenous thrombosis. We measured the expression of ACA and anti-β2-GP1 antibodies in the serum of pregnant women early in their pregnancy, and analyzed the pregnancy outcome of the primigravidas who were positive for both the antibodies, so as to evaluate the efficacy of the combined determination in predicting pregnancy outcome. A total of 102 pregnant women who visited the Hebei General Hospital from January 2014 to December 2017 were enrolled in the study. The serum levels of ACA and anti-β2-GP1 antibodies were determined in all the enrolled pregnant women using the enzyme-linked immunosorbent assay (ELISA) method and the correlation between positive ACA/anti-β2-GP1 antibody and the adverse pregnancy outcomes was analyzed. Meanwhile, the difference in the pregnancy outcomes between patients who were positive for ACA only, for anti-β2-GP1 only and for both of the two antibodies was also investigated. The incidence of adverse pregnancy outcomes of pregnant women who were positive for both the ACA and the anti-β2-GP1 antibodies (48.87%) was higher than that of those positive for ACA only (28.67%) and those positive for anti-β2-GP1 only (36.66%). The positive predictive value (PPV), negative predictive value (NPV), sensitivity and specificity of the combined determination of the two predictors was 81.75%, 95.84%, 88.37% and 95.92%, respectively. The combined determination of ACA and anti-β2-GP1 antibodies early in pregnancy may predict the occurrence of pregnancy outcome, with superiority over either of the two predictors alone.

Longitudinal Analysis of Anti-cardiolipin and Anti-β2-glycoprotein-I Antibodies in Recent-Onset Systemic Lupus Erythematosus: A Prospective Study in Swedish Patients

Background: Anti-phospholipid syndrome (APS) and systemic lupus erythematous (SLE) are autoimmune disorders that often co-occur. Anti-phospholipid antibodies (aPL) are typical of both conditions and may be associated with vascular events and pregnancy-related morbidities. Whereas, aPL-screening is mandatory for individuals with suspected SLE, the clinical value of longitudinal aPL analyses in established SLE is unclear.

Methods: We investigated the occurrence and variation of IgG/IgA/IgM anti-cardiolipin (aCL) and anti-β2-glycoprotein-I (anti-β2GPI) antibodies, using both the manufacturer's cut-off and a cut-off based on the 99th percentile of 400 apparently healthy donors, in recent-onset SLE. Furthermore, we evaluated the relationships between aPL levels and SLE/APS manifestations, as well as the pharmacotherapy. Patients with SLE who met validated classification criteria were included in this prospective study (N = 54). Samples were obtained at 0, 6, 12, 24, 36, 48, 60, 72, 84, and 96 months after SLE diagnosis.

Results: Depending on the cut-off applied, 61.1 or 44.4% showed a positive result for at least one aPL isotype or the lupus anticoagulant test over time. Median values for all six aPL isotypes numerically decreased from inclusion to last follow-up, but none of the isotypes met statistical significance. Seroconversion (from positive to negative, or the opposite direction) was occasionally seen for both aCL and anti-β2GPI. IgA and IgM anti-β2GPI were the most common isotypes, followed by IgM aCL. Presence of IgG aCL associated significantly with myocardial infarction and miscarriage, and IgG/IgA anti-β2GPI with miscarriage.

Conclusion: aPL were common during the first years of SLE. Even though the levels fluctuated over time, the patients tended to remain aPL positive or negative. Repeated aPL testing in the absence of new symptoms seems to be of uncertain value in patients with recent-onset SLE.

Validation of the Particle-Based Multi-Analyte Technology for Detection of Anti-PhosphatidylSerine/Prothrombin Antibodies

Among “extra-criteria” antiphospholipid (aPL) antibodies, anti-phosphatidylserine/prothrombin (aPS/PT) antibodies, are considered a part of risk assessment strategies when investigating patients suspected of having antiphospholipid syndrome (APS). aPL detection is currently performed by solid-phase assays to identify anti-cardiolipin (aCL), anti-β2glycoprotein I (aβ2GPI) and aPS/PT antibodies, but new techniques are emerging. Among these, particle-based multi-analyte technology (PMAT), which allows the full automation and simultaneous digital detection of autoantibodies and proteins, including IgG, IgA and IgM isotypes of aCL, aβ2GPI and aPS/PT. The aim of this study was to investigate the agreement of aPS/PT testing between enzyme-linked immunosorbent assay (ELISA) and the PMAT platform. A total of 94 patients were enrolled in the study, including 71 patients with confirmed APS and 23 “aPL carriers”. aPS/PT IgG showed a moderate binomial agreement between ELISA and PMAT (k = 0.57, 95% CI 0.45–0.75), and aPS/PT IgM showed a moderate agreement (k = 0.60, 95% CI 0.45–0.75). Moreover, when considering the continuous agreement, both aPS/PT IgG and IgM showed a statistically significant correlation between ELISA and PMAT (Spearman’s correlation = 0.69, p < 0.001 and 0.72, p < 0.001, respectively). This study demonstrates that PMAT technology is a reliable method for aPS/PT IgG and IgM testing when compared to the available commercial ELISA kit.

The Weight of IgA Anti-β2glycoprotein I in the Antiphospholipid Syndrome Pathogenesis: Closing the Gap of Seronegative Antiphospholipid Syndrome

The specific value of IgA Anti-β2glycoprotein I antibodies (aB2GP1) in the diagnosis and management of antiphospholipid syndrome (APS) is still controversial and a matter of active debate. The relevance of the IgA aB2GP1 isotype in the pathophysiology of APS has been increasingly studied in the last years. There is well know that subjects with multiple positive APS tests are at increased risk of thrombosis and/or miscarriage. However, these antibodies are not included in the 2006 APS classification criteria. Since 2010 the task force of the Galveston International Congress on APS recommends testing IgA aB2GP1 isotype in patients with APS clinical criteria in the absence of criteria antibodies. In this review, we summarize the molecular and clinical “state of the art” of the IgA aB2GP in the context of APS. We also discuss some of the characteristics that may help to evaluate the real value of the IgA aB2GP1 determination in basic research and clinical practice. The scientific community should be aware of the importance of clarifying the role of IgA aB2GP1 in the APS diagnosis.

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.

High IgA antiphospholipid autoantibodies in healthy Sudanese explain the increased prevalence among Sudanese compared to Swedish systemic lupus erythematosus patients

Objectives

IgA antiphospholipid antibodies (aPL) are prevalent in systemic lupus erythematosus (SLE) patients of African American, Afro-Caribbean and South African origin. Nevertheless, data from North Africa are lacking, and most studies use manufacturer-suggested cut-offs based on Caucasian controls. Therefore, we compared aPL isotypes in Sudanese and Swedish SLE patients using nation-based cut-offs.

Methods

Consecutive SLE patients and age- and sex-matched controls from Sudan (N = 115/106) and Sweden (N = 340/318) were included. All patients fulfilled the 1982 American College of Rheumatology SLE classification criteria. Antiphospholipid syndrome–related events were obtained from patients’ records. IgA/G/M anticardiolipin and anti-β₂ glycoprotein I (β₂GPI) were analysed with two independent assays. IgA anti-β₂GPI domain 1 (D1) was also investigated. Manufacturers’ cut-offs and the 95th and 99th percentile cut-offs based on national controls were used.

Results

Sudanese patients and controls had higher levels and were more often positive for IgA aPL than Swedes when using manufacturers’ cut-offs. In contrast, using national cut-offs, the increase in IgA aPL among Sudanese patients was lost. Occurrence of IgA anti-D1 did not differ between the countries. Venous thromboses were less common among Sudanese patients and did not associate with aPL. No clinical associations were observed with IgA anti-β₂GPI in Sudanese patients. Thromboses in Swedes were associated with IgG/M aPL. Fetal loss was associated with aPL in both cohorts.

Conclusions

IgA anti-β₂GPI prevalence was higher among Sudanese compared to Swedish patients when manufacturers’ cut-offs were used. This situation was reversed when applying national cut-offs. Anti-D1 was not increased in Sudanese patients. Previous studies on populations of African origin, which demonstrate a high prevalence of IgA aPL positivity, should be re-evaluated using a similar cut-off approach.