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

Abstract

PurposeTo 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).MethodsFour 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.ResultsOverall, 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.ConclusionsThe 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.

Dilute Russell’s viper venom time reagents in lupus anticoagulant testing: a well-considered choice

“…Patients showed thrombosis (12/13) or miscarriage (1/13). Although Haematex mainly missed APS patients with LAC alone, and did detect 7/8 APS patients with more than one laboratory criterion, this does not imply that Haematex detects 'more relevant' LAC, as 29.3% of the genuine APS patient are reported to be only LAC positive [37]. Five out of the six consecutive APS patients, also positive in the aPTT The formulas for the screen and confirm test result are described in the legend of Figure 1.…”

Exploring the plasmatic platelet-activating factor acetylhydrolase activity in patients with anti-phospholipid antibodies

“…We and others recently demonstrated an important role of aPS/PT antibodies in the serological diagnosis of APS [5, 26]; however, the therapeutic management of patients characterized by the presence of isolated aPS/PT remains an open issue. Patients with isolated aPS/PT antibodies disclosed lower, BDs-like, PAF-AH as compared to patients with positive aβ2GPI antibodies.…”

“…However, during the last international congress on aPL antibodies, the major experts defined the role of other so-called “non criteria” antibodies, contributing to assess the risk of thrombosis or the identification of potential seronegative APS, such as the anti-prothrombin/phosphatidylserine antibodies (aPS/PT) [3]. Of note, the combination of aβ2GPI, aPS/PT and LAC has demonstrated the best diagnostic accuracy for APS [4] and aPS/PT were recently recommended as a surrogate for LAC when specific inhibitors and/or analytical variables may affect its interpretation [5]. However, no definite recommendations are available to guide the therapeutic approach in patients positive only for aPS/PT antibodies.…”

Lupus anticoagulant

“…A correlation between the level of combined positivity and an increased risk of thrombosis or pregnancy losses has not yet been proven [14,16,18,21,31]. Score definition -as devised in this study -helps to accurately assess risks in appropriate case studies by combining additional clinical trials with the detection of antiphospholipid antibodies in solid phase [32][33][34]. Moreover, future clinical outcome studies, using our stratification criteria, need to be performed, using different analytical platforms and reagents, to confirm the benefit of this approach.…”