Anti-phospholipid antibodies and reproductive failures

Anti-phospholipid syndrome (APS) recapitulates the link between autoimmunity and pregnancy failure: Acquired anti-phospholipid antibodies (aPL) play a pathogenic role in pregnancy complications. The diagnosis of obstetric APS can easily be pursued when women present with laboratory and clinical features fulfilling the international classification criteria. Standard therapeutic approach to obstetric APS consists in the association of anti-platelet agents and anticoagulants. Most patients achieve a live birth thanks to conventional treatment; however, approximately 20% fail to respond and are managed with additional therapeutic tools added on the top of conventional treatment. Surely, a refinement of risk stratification tools would allow early identification of high-risk pregnancies that warrant tailored treatment. In real life, obstetricians and rheumatologists face complex diagnostic scenarios including women with pregnancy morbidities other than those mentioned in classification criteria such as one or two early losses and premature birth after 34 weeks due to preeclampsia or placental insufficiency, women with low-titer aPL not fulfilling criteria laboratory requirements, women with positive non-criteria aPL, asymptomatic aPL carriers, and infertile women found to be aPL-positive. This review focuses on some of the several unanswered questions related to diagnostic, prognostic, and therapeutic aspects in obstetric APS.

Antiphosphatidylserine/prothrombin complex antibodies as a determinant of prothrombotic plasma fibrin clot properties in patients with antiphospholipid syndrome

BACKGROUND

Antiphosphatidylserine/prothrombin complex (aPS/PT) antibodies are recognized as a marker for antiphospholipid syndrome (APS). Dense and poorly lysable fibrin clots occur in thrombotic APS. Compact clots predict thromboembolism, but determinants of the unfavorable clot phenotype remain unknown in APS. We hypothesized that elevated aPS/PT antibodies determine unfavorable clot features.

METHODS

In a cohort study involving 124 consecutive patients with thrombotic APS, we measured at baseline plasma fibrin clot permeability (Ks ), efficiency of fibrinolysis (clot lysis time, CLT), and turbidity (off anticoagulation) along with immunoglobulin (Ig)G/IgM aPS/PT. During follow-up, symptomatic thromboembolic events were recorded.

RESULTS

Elevated IgG and IgM aPS/PT antibodies >30 international enzyme units (UI) were detected in 54.8% and 42.7% of APS patients, including 76.2% and 54% of lupus anticoagulant- (LA, n = 63) positive patients, respectively. Elevated IgG and IgM aPS/PT antibodies predicted low Ks (lower quartile, <6 × 10-9  cm2 ; odds ratio [OR] = 5.93, 95% confidence interval [CI] 2.09-16.82 and OR = 11.79, 95% CI 4.10-33.92) and prolonged CLT (top quartile, ≥116 min; OR = 4.85, 95% CI 2.42-25.07 and OR = 6.04, 95% CI 2.42-15.07). No such associations were observed for anticardiolipin or β2-glycoprotein I antibodies or LA presence. During follow-up (median 72.5, range 66-83 months), thromboembolic events observed in 32 (26.7%, 4.6%/year) patients were independently predicted by IgG aPS/PT antibodies >30 UI (hazard ratio [HR] = 3.04, 95% CI 1.20-8.88) and low Ks (HR = 3.00, 95% CI 1.41-6.50).

CONCLUSIONS

We identified aPS/PT antibodies as a determinant of denser and poorly lysable plasma fibrin clot formation in APS patients. The association of elevated aPS/PT antibodies with thromboembolism in APS could be at least in part mediated by prothrombotic clot properties.

Guidelines for biomarkers in autoimmune rheumatic diseases - evidence based analysis

Autoimmune rheumatic diseases are characterised by an abnormal immune system response, complement activation, cytokines dysregulation and inflammation. In last years, despite many progresses in managing these patients, it has been shown that clinical remission is reached in less than 50% of patients and a personalised and tailored therapeutic approach is still lacking resulting in a significant gap between guidelines and real-world practice. In this context, the need for biomarkers facilitating early diagnosis and profiling those individuals at the highest risk for a poor outcome has become of crucial interest. A biomarker generally refers to a measured characteristic which may be used as an indicator of some biological state or condition. Three different types of medical biomarkers has been suggested: i. mechanistic markers; ii. clinical disease markers; iii. therapeutic markers. A combination of biomarkers from these different groups could be used for an ideal more accurate diagnosis and treatment. However, although a growing body of evidence is focused on improving biomarkers, a significant amount of this information is not integrated on standard clinical care. The overarching aim of this work was to clarify the meaning of specific biomarkers during autoimmune diseases; their possible role in confirming diagnosis, predicting outcome and suggesting specific treatments.

Prevalence and associations of anti-phosphatidylserine/prothrombin antibodies with clinical phenotypes in patients with primary antiphospholipid syndrome: aPS/PT antibodies in primary antiphospholipid syndrome

OBJECTIVE

The clinical significance of anti-phosphatidylserine/prothrombin (aPS/PT) in antiphospholipid syndrome (APS) is still controversial. We assessed the prevalence of aPS/PT antibodies, their association with other anti-phospholipid antibodies (aPL) and with different APS clinical phenotypes.

METHODS

We included 95 primary APS patients according to the Sydney classification criteria, and patients with thrombocytopenia and/or hemolytic anemia who also fulfilled the serological APS criteria. We tested aCL, anti-β2GP-I and aPS/PT antibodies (both IgG and IgM isotypes) and lupus anticoagulant (LA). We used χ2 test, Spearman's correlation coefficient, Mann-Whitney U test and logistic regression.

RESULTS

Seventy-seven percent of patients had thrombosis, 50% hematologic involvement and 25% obstetric events (non-exclusive groups). Twenty patients had only hematologic features. The prevalence of IgG and IgM aPS/PT antibodies was 61% and 60%, respectively. Patients with LA+ had a higher prevalence and higher titers of IgG and IgM aPS/PT antibodies. aPS/PT antibodies correlated with aPL antibodies including LA. IgG aPS/PT antibodies were associated with thrombosis (OR 8.6 [95% CI 2.13-33.8, p = 0.002]) and pure hematologic features (OR 0.2, CI 95% 0.05-0.97, p = 0.004). IgM anti-β2GP-I antibodies conferred high risk for both hematologic (OR 7.9, 95% CI 1.88-34.61, p = 0.006) and thrombotic involvement (OR 7.4, 95% CI 1.76-31.12, p = 0.006).

CONCLUSIONS

aPS/PT antibodies were highly prevalent and correlated with other aPL antibodies. IgG aPTS/PT conferred a high risk for thrombosis, but not for pure hematologic involvement. aPS/PT antibodies may be a useful serological tool in the diagnosis and phenotypic characterization of APS patients.

Antiphosphatidylserine/prothrombin Antibodies in Antiphospholipid Syndrome with Intrauterine Growth Restriction and Preeclampsia

OBJECTIVE

Antibodies that recognize the phosphatidylserine/prothrombin complex (antiphosphatidylserine/prothrombin antibodies; aPS/PT) might reveal enhanced thrombotic risk in patients with systemic lupus erythematosus. Little is known about their association with pregnancy complications in the antiphospholipid syndrome (APS).

METHODS

We enrolled 55 patients with APS who were seeking pregnancy in 2 Italian hospitals. Antiphospholipid antibodies (aPL), including anticardiolipin antibodies, anti-β₂-glycoprotein I antibodies, lupus-like anticoagulant, and aPS/PT antibodies were assessed, and the patients were prospectively followed for 24 months.

RESULTS

There were 65% (36/55) of the APS patients who had aPS/PT antibodies. Forty-seven pregnancies were followed, including 33 of aPS/PT+ patients. Forty-one of the 47 patients (87%) who initiated a pregnancy eventually gave birth to a child. The pregnancy duration and the mean newborn weight at delivery were significantly lower in aPS/PT+ than in aPS/PT- patients (33.1 ± 4.7 vs 36.2 ± 3.4 wks of gestation, respectively, and 2058 ± 964 g vs 2784 ± 746 g, respectively, p < 0.05). Late pregnancy complications, including intrauterine fetal death, preterm delivery, preeclampsia, and intrauterine growth restriction (IUGR), were more frequent in aPS/PT+ patients, independent of the therapy. Titers of aPS/PT IgG were significantly inversely correlated with the neonatal weight at delivery. Vascular injury, as reflected by thrombosis, fibrinoid necrosis, ischemic and hemorrhagic areas, and presence of chorangiomas characterized the IUGR placentas in the presence of aPS/PT.

CONCLUSION

The aPS/PT antibodies might represent markers of aPL-related pregnancy complications, IUGR/preeclampsia in particular, and could help identify beforehand patients who may require additional treatment.

Antiphosphatidylserine/prothrombin (aPS/PT) antibodies are associated with Raynaud phenomenon and migraine in primary thrombotic antiphospholipid syndrome

Objectives

Antibodies to phosphatidylserine/prothrombin complex (aPS/PT) detectable in sera of some patients with antiphospholipid syndrome (APS) have been shown to correlate with thrombosis. However, associations of aPS/PT antibodies with APS related disorders remain unclear.

Aim

To evaluate whether there are any associations between aPS/PT antibodies and Raynaud phenomenon, migraine and/or valvular lesions in primary thrombotic APS (PAPS).

Methods

We enrolled 67 consecutive patients (56 women) with thrombotic PAPS (VTE in 80.6%), aged 46.2 ± 13.5 years. The exclusion criteria were: acute coronary syndromes or stroke within preceding 6 months, cancer, severe comorbidities and pregnancy. The IgG and IgM aPS/PT antibodies were determined by ELISA with the cut-off of 30 units. We recorded Raynaud phenomenon, migraine and valvular lesions.

Results

Positive IgM or/and IgG aPS/PT antibodies were observed in 29 patients (43.3%), with a higher prevalence of IgM antibodies ( n = 27, 40.3%) compared with IgG isotype ( n = 12, 17.9%, p = 0.014). aPS/PT antibodies were observed most commonly in patients with triple aPL ( n = 12, 85.7%) compared with those with double ( n = 5, 35.7%) or single aPL antibodies (n = 12, 30.8%, p = 0.03), with no association with demographics, the ANA titre, the type of thrombotic events or medications. Raynaud phenomenon, migraine and valvular lesions were observed in 15% ( n = 10), 30% ( n = 20) and 18% ( n = 12) of the patients, respectively. Raynaud phenomenon and migraine, but not valvular lesions, were markedly more frequent in PAPS patients presenting with positive aPS/PT antibodies ( n = 10, 34.5% vs. n = 0, 0%; p = 0.0001).

Conclusions

In PAPS patients aPS/PT antibodies are related to the occurrence of both Raynaud phenomenon and migraine.

Antiphosphatidylserine/prothrombin antibodies as biomarkers to identify severe primary antiphospholipid syndrome

Background:

Anti-phosphatidylserine/prothrombin (aPS/PT) antibodies have begun to be considered potentional biomarkers for antiphospholipid syndrome (APS). This cohort study investigate the role of aPS/PT antibodies as a risk factor for severe APS by evaluating the association between those antibodies and clinical/laboratory profiles of APS.

Methods:

Plasma/serum samples from 197 APS patients, 100 healthy subjects and 106 patients with autoimmune diseases were collected. IgG/IgM aPS/PT antibodies were assayed using commercial ELISA kit.

Results:

Prevalences of IgG and IgM aPS/PT (p<0.0001 and p=0.0009, respectively) and their titres (p<0.0001 and p=0.0002, respectively) were significantly higher in thrombosis/pregnancy group with respect to pregnancy morbidity alone. Prevalences of IgG and IgM aPS/PT (p<0.0001 and p=0.0004, respectively) and their mean levels (p=0.0001 for both) were significantly higher in the prematurity linked to life-threatening obstetric complications group with respect to miscarriage group. There was a significant relationship between IgG and IgM aPS/PT (p=0.001 and p=0.0002) and their mean levels were higher (p=0.0004 and p=0.0002, respectively) in the thrombotic microangiopathy group, considered a milestone manifestation of catastrophic APS. The relationship between IgG and IgM aPS/PT was significant and mean levels were higher in triple positive antiphospholipid antibody patients than in double and single positivity ones (p<0.0001 for all).

Conclusions:

APS/PT antibodies were associated to severe thrombosis, severe pregnancy complications inducing prematurity, and vascular microangiopathy, all generally associated to high risk APS forms requiring strong therapy.

Diagnostic value of antibodies to phosphatidylserine/prothrombin complex for antiphospholipid syndrome in Chinese patients

To evaluate the diagnosis value of antibodies to phosphatidylserine/prothrombin complex (aPS/PT) in patients with antiphospholipid syndrome (APS) and to determine the clinical features of APS patients with avidity of aPS/PT. Serum samples were collected from 108 APS patients. Sixty patients with pregnancy morbidity, 37 patients with thrombosis without a history of autoimmune diseases, and 89 healthy blood donors were included as the control group. The enzyme-linked immunosorbent assay (ELISA) test was performed to detect the concentration of aPS/PT, including IgG/M, IgG, and IgM forms, in the same serum sample. The chi-square (χ2) test was used to examine the difference of frequencies of antibodies in APS patients and patients with other diseases. Spearman correlation analysis was performed to investigate the relationship between aPS/PT and other clinical/laboratory parameters. aPS/PT was detectable in 68 (63.0%) of the 108 APS patients, 12 (13.2%) of the 91 disease control patients and 1 (1.1%) of the healthy controls. It was strongly correlated with the activity of lupus anticoagulant (LA) (OR 15.952, 95% CI 7.132-35.678; P < 0.001). The frequency of aPS/PT was 56.9% in anti-cardiolipid antibody (aCL)-negative, 60.5% anti-β2 glycoprotein I antibody (aβ2GPI)-negative, and 50.0% in both aCL and aβ2GPI negative APS patients. The IgG aPS/PT was significantly associated with arterial and venous thrombosis. The aPS/PT antibody could play an important role in the diagnosis of APS, especially in patients with negative aCL and aβ2GPI. It was positively related to thrombotic events in APS.

Prevention of thrombosis in antiphospholipid syndrome

Antiphospholipid syndrome (APS) is an acquired autoimmune condition characterized by thrombotic events, pregnancy morbidity, and laboratory evidence of antiphospholipid antibodies (aPL). Management of these patients includes the prevention of a first thrombotic episode in at-risk patients (primary prevention) and preventing recurrent thrombotic complications in patients with a history of thrombosis (secondary prevention). Assessment of thrombotic risk in these patients, balanced against estimated bleeding risks associated with antithrombotic therapy could assist clinicians in determining whether antithrombotic therapy is warranted. Thrombotic risk can be assessed by evaluating a patient's aPL profile and additional thrombotic risk factors. Although antithrombotic options for secondary prevention of venous thromboembolism (VTE) have been evaluated in clinical trials, studies in primary prevention of asymptomatic aPL-positive patients are needed. Primary prevention with aspirin may be considered in asymptomatic patients who have a high-risk aPL profile, particularly if additional risk factors are present. Secondary prevention with long-term anticoagulation is recommended based on estimated risks of VTE recurrence, although routine evaluation of thrombotic risk can assist in determining whether ongoing anticoagulation is warranted. Studies that stratify thrombotic risk in aPL-positive patients, and patients with APS evaluating antithrombotic and non-antithrombotic therapies will be useful in optimizing the management of these patients.

Evaluation of phosphatidylserine-dependent antiprothrombin antibody testing for the diagnosis of antiphospholipid syndrome: results of an international multicentre study

Objective A task force of scientists at the International Congress on Antiphospholipid Antibodies recognized that phosphatidylserine-dependent antiprothrombin antibodies (aPS/PT) might contribute to a better identification of antiphospholipid syndrome (APS). Accordingly, initial and replication retrospective, cross-sectional multicentre studies were conducted to ascertain the value of aPS/PT for APS diagnosis. Methods In the initial study (eight centres, seven countries), clinical/laboratory data were retrospectively collected. Serum/plasma samples were tested for IgG aPS/PT at Inova Diagnostics (Inova) using two ELISA kits. A replication study (five centres, five countries) was carried out afterwards. Results In the initial study ( n = 247), a moderate agreement between the IgG aPS/PT Inova and MBL ELISA kits was observed ( k = 0.598). IgG aPS/PT were more prevalent in APS patients (51%) than in those without (9%), OR 10.8, 95% CI (4.0-29.3), p < 0.0001. Sensitivity, specificity, positive (LR+) and negative (LR-) likelihood ratio of IgG aPS/PT for APS diagnosis were 51%, 91%, 5.9 and 0.5, respectively. In the replication study ( n = 214), a moderate/substantial agreement between the IgG aPS/PT results obtained with both ELISA kits was observed ( k = 0.630). IgG aPS/PT were more prevalent in APS patients (47%) than in those without (12%), OR 6.4, 95% CI (2.6-16), p < 0.0001. Sensitivity, specificity, LR + and LR- for APS diagnosis were 47%, 88%, 3.9 and 0.6, respectively. Conclusions IgG aPS/PT detection is an easily performed laboratory parameter that might contribute to a better and more complete identification of patients with APS.

Relationship between antiphosphatidylserine/prothrombin and conventional antiphospholipid antibodies in primary antiphospholipid syndrome

BACKGROUND

Antiphosphatidylserine/prothrombin complex (aPS/PT) antibodies are emerging as an important marker for antiphospholipid syndrome (APS). We aimed to compare their performance with that of conventional antiphospholipid antibodies (aPL) such as lupus anticoagulant (LA), anticardiolipin (aCL), and anti-β2-glycoprotein I (anti-β2GPI) in APS and to assess their frequency in APS-negative (APS-ne) patients.

METHODS

We considered 160 APS patients and 128 APS-ne patients with clinical criteria for APS but tested negative for conventional aPL. Immunoglobulin (Ig)G/IgM aPS/PT, IgG/IgM aCL, and IgG/IgM anti-β2GPI were detected using ELISA assay and LA with a series of coagulation tests.

RESULTS

IgG aPS/PT were significantly associated with IgG aCL, IgG anti-β2GPI, and LA (p<0.0001 for all). IgM aPS/PT were significantly associated only with LA (p<0.0001) instead. There was a significant correlation between IgG aPS/PT and both IgG aCL and IgG anti-β2GPI levels (ρ=0.42 and ρ=0.40, respectively). Both IgG aPS/PT and IgM aPS/PT positivity significantly correlated with LA (ρ=0.44 and ρ=0.5, respectively). IgG and IgM aPS/PT were significantly more frequent in triple than in double and in single positivity (p<0.0001). According to multivariate analysis, IgG and/or IgM aPS/PT were independent risk factors for LA. APS/PT antibodies were found in 9.4% of the APS-ne patients vs. 2% of healthy control (p=0.043); those antibodies were significantly more frequent in the thrombosis with respect to the pregnancy morbidity subset (p=0.01).

CONCLUSIONS

Our data attribute a clinical relevance to both IgG and IgM aPS/PT antibodies. In particular, the significant prevalence of aPS/PT in APS-ne patients suggests including them as additional laboratory criterion for APS.

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.

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 (aβ2 GPI) IgG and/or IgM; samples were retained and analysed for aPS/PT, aCL and/or aβ2 GPI 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 aβ2 GPI 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/aβ2 GPI IgG/aCL IgG [AUC 0·979, OR 475·4, 95% confidence interval (CI) 23·1-9056·5, P = 0·0001 and LAC/aβ2 GPI 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.

Bouquet variety of antiphospholipid antibodies in recurrent pregnancy loss

Seventy-six female patients with two or more recurrent pregnancy losses (RPL) during the 1(st) trimester were studied. Based on the results of the aCL and aB2GPI antibodies testing, patients were divided in two groups: 22 patients with RPL and elevated immunoglobulin (Ig) G/IgM aCL and/or aB2GPI [RPL + antiphospholipid syndrome (APS)] and 54 patients with RPL alone (without high antibodies). Immunoglobulin G aPS and IgG a-AnV in patients with RPL + APS were higher than in controls and IgG aPS were higher in RPL + APS than in RPL alone. Additionally IgG a-AnV and IgM aPE are higher in RPL alone than in controls. In 18/22 (81%) patients with RPL + APS and 29/54 (54%) patients with RPL alone, there were one or more positive antibodies: aPS, aPT, a-AnV or aPE. These results raise a question whether or not these antiphospholipid antibodies should be routinely tested in women with RPL and especially in the context of the so-called "seronegative APS".

Hypercoagulability in celiac disease--an update

Celiac disease is a life-long autoimmune disease affecting multiple organs of genetically susceptible individuals. One of the extra intestinal manifestations of the disease is thromboembolic events like strokes, veins' thrombosis, and pregnancy losses. Hypercoagulable autoimmune diseases like lupus erythematosus and antiphospholipid syndrome, associated with celiac disease just add risk to the patients. Pathogenic predisposing avenues increasing the hypercoagulability in celiac disease are multiple: nutritional deficiencies (B12, folate, and vitamin K), genetic predisposition (MTHFR mutations), thrombophilic autoantibodies, hyperhomocysinemia, endothelial dysfunction and platelet abnormalities. Primary pharmacologic thromboprophylaxis or treating the predisposing factors should be considered on a personal basis.

The introduction of anti-phosphatidylserine/prothrombin autoantibodies in the laboratory diagnostic process of anti-phospholipid antibody syndrome: 6 months of observation

PURPOSE

To evaluate the impact of the introduction of the anti-phosphatidylserine/prothrombin autoantibodies (aPS/PT) in the laboratory diagnostic process of anti-phospholipid antibody syndrome (APS).

METHODS

Four hundred and twenty-one patients (71.5 % females; 53 ± 15 years) presenting a medical prescription for aPS/PT antibodies were consecutively enrolled in the study from March 2013 to August 2013. During the same period, aPS/PT were additionally investigated in a selected series of 62 patients characterized by difficult lupus anticoagulant (LA) tests interpretation and in a retrospective series of 52 LA positive cases with available data about anti-prothrombin (aPT) antibodies. The aPS/PT antibodies, as well as the anti-cardiolipin (aCL), the anti-β2 glycoprotein I (aβ2GPI) and the aPT antibodies were analyzed by ELISA. LA was tested according to the recommended criteria, performing both the screen and the confirm steps.

RESULTS

Overall, aPS/PT IgM positive (>30 U/ml) and/or IgG frankly positive (>40 U/ml) antibodies were found in 49/421 (11.6 %) cases. Among the LA positive patients, we found 56.1 % aPS/PT positive versus 31.7 % aCL and/or aβ2GPI positive cases, with limited (17.1 %) simultaneous positivity. The PS/PT complex resulted the newly recognized specificity in about 27 % of patients recruited from the subset with difficult LA test interpretation. Compared to aPT antibodies, the aPS/PT antibodies displayed a much higher sensitivity (55.8 versus 15.4 %) in LA positive patients.

CONCLUSIONS

The introduction of aPS/PT antibodies in the diagnostic process of APS is highly recommended, since they disclose a notable diagnostic performance and a high correlation with LA activity, such that they can be a viable alternative.

Anti-prothrombin (aPT) and anti-phosphatidylserine/prothrombin (aPS/PT) antibodies and the risk of thrombosis in the antiphospholipid syndrome. A systematic review

Antibodies to prothrombin are detected by directly coating prothrombin on irradiated ELISA plates (aPT) or by using the phosphatidylserine/prothrombin complex as antigen (aPS/PT). Although these antibodies have both been associated with antiphospholipid syndrome (APS) and a correlation between the two assays have been reported, it seems that aPT and aPS/PT belong to different populations of autoantibodies. It was our objective to systematically review the available evidence on aPT and aPS/PT antibodies and the risk of thrombosis in APS. Medline-reports published between 1988 and 2013 investigating aPT and aPS/PT as a risk factor for thrombosis were included. Whenever possible, antibody isotype(s) and site of thrombosis were analysed. This systematic review is based on available data from more than 7,000 patients and controls from 38 studies analysing aPT and 10 aPS/PT. Antibodies to prothrombin (both aPT and aPS/PT) increased the risk of thrombosis (odds ratio [OR] 2.3; 95% confidence interval [CI] 1.72-3.5). aPS/PT seemed to represent a stronger risk factor for thrombosis, both arterial and/or venous than aPT (OR 5.11; 95%CI 4.2-6.3 and OR 1.82; 95%CI 1.44-2.75, respectively). In conclusion, routine measurement of aPS/PT (but not aPT) might be useful in establishing the thrombotic risk of patients with previous thrombosis and/or systemic lupus erythematosus. Their inclusion as laboratory criteria for the APS should be indisputably further explored.

Antibodies to phosphatidylserine/prothrombin complex in suspected antiphospholipid syndrome in the absence of antibodies to cardiolipin or Beta-2-glycoprotein I

Antibodies to phosphatidylserine/prothrombin (aPS/PT) complex were measured in 728 serum specimens from patients suspected of having antiphospholipid syndrome (APS), but without diagnostic elevations in the levels of antibodies to cardiolipin or Beta-2 Glycoprotein 1 (β2-GP1). Of the 728 specimens, 41 had elevated levels of aPS/PT. Thrombotic events occurred in 11 of the 22 patients with accessible medical histories. Six of the patients with accessible medical records also had laboratory evidence of the lupus anticoagulant. The identification of aPS/PT in patients without evidence of antibodies to cardiolipin, β2-GP1, or the lupus anticoagulant can contribute to the identification of APS in patients that may go undetected with current testing methods.

The thrombophilic network of autoantibodies in celiac disease

BACKGROUND

Celiac disease is a life-long autoimmune condition, affecting genetically susceptible individuals that may present with thromboembolic phenomena. This thrombophilia represents a puzzle with multiple constituents: hyperhomocysteinemia, B12 and\or folate deficiency, methylenetetrahydrofolate reductase mutations, and protein C and S deficiency due to vitamin K deficiency. However, the well known thrombogenic factors, antiphosphatidylserine/prothrombin and antiprothrombin have never been explored in celiac disease.

METHODS

The serum autoantibody levels were determined in 248 individuals, classified into three groups. Group 1 comprised 70 children with definitive celiac disease (age: 7.04 ±4.3 years, male to female ratio 1.06) and group 2 comprised 88 normal children (age: 6.7 ±4.17 years, male to female ratio 0.87), representing controls. The pediatric populations were compared to group 3, which included 90 adults who were family members (parents) of group 1 (age: 34.6 ±11.35 years, male to female ratio 1.2). Antibodies were checked by enzyme-linked immunosorbent assay.

RESULTS

Mean optical density levels of serum antiphosphatidylserine/prothrombin immunoglobulin G antibodies were 32.4 ±19.4, 3.6 ±2.5 and 16.1 ±15.8 absorbance units in groups 1, 2 and 3 respectively (P <0.0001), with 45.7%, 0% and 7.8% of groups 1, 2 and 3 respectively positive for the antibody (P <0.01). Mean optical density levels of serum antiphosphatidylserine/prothrombin immunoglobulin M antibodies were 14.2 ±8.7, 6.7 ±6.4 and 12.4 ±15.5 absorbance units in groups 1, 2 and 3 respectively (P <0.0001), with 7.1%, 3.4% and 9.9% of groups 1, 2 and 3 positive for the antibody. Mean optical density levels of serum antiprothrombin and antiphospholipid immunoglobulin G antibodies were higher in groups 1 and 3 compared with 2 (P <0.005) and in groups 1 and 2 compared with 3 (P <0.01), respectively. Groups 1, 2 and 3 were positive for antiphospholipid immunoglobulin G antibodies (groups 1 and 2 compared with 3) . Celiac disease sera harbor a higher antiprothrombin immunoglobulin G level compared with controls.

CONCLUSIONS

It is suggested that the intestinal injury, endothelial dysfunction, platelet abnormality and enhanced apoptosis recently described in celiac disease are at the origin of the increased exposure of phospholipids or new epitopes representing autoantigens. Those autoantibodies might play a pathogenic role in the thrombophilia associated with celiac disease and represent markers for potential anticoagulant preventive therapy.