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

Abstract

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.

Laboratory methods to detect antiphospholipid antibodies

“…There has been a flurry of activity in the development of ELISAs that detect aAbs targeting the PS/PT complex, with some promising results with regard to their potential diagnostic value. 50 Larger studies involving multiple centers and, preferably, multinational research collaborations will be necessary before accepting the clinical utility of such findings. Several other active areas of ongoing research based on promising emerging data include determining the diagnostic utility of a novel domain I-specific anti-␤ 2 GPI ELISA and the relevance of IgA anti-␤ 2 GPI aAbs.…”

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

“…[8][9][10][11][12][13][14][15][16][17][18][19][20] A recent systematic review suggested that both antibodies against prothrombin, aPT-A and aPS/PT, are risk factors for thrombosis, but that aPS/PT represent a stronger risk factor for arterial and/or venous thrombosis when compared to aPT-A. 21 In two prospective studies, the presence of aPT-A has been reported as a predictor of thromboembolic events in patients with aPL, mainly in those patients positive for LA. 22,23 Many reports have shown the clinical utility of aPS/PT in the diagnosis of APS.…”

Can we withdraw anticoagulation in patients with antiphospholipid syndrome after seroconvertion?

“…When evaluating the diagnostic accuracy of several aPL specificities combinations, the profile including LA + anti-β2GPI + aPS/PT held the best diagnostic accuracy for APS even when subdividing the study group into those with thrombosis and those with pregnancy loss [29]. In addition, aPS/PT have been confirmed as a strong risk factors for thrombosis, irrespective of the site and type of thrombosis.…”

“…In addition, aPS/PT have been confirmed as a strong risk factors for thrombosis, irrespective of the site and type of thrombosis. Their presence incurred in an odds ratio (OR) for thrombosis 3 to 18 times higher than in various control groups [29].…”

“…While these antibodies are known to be directed to the same molecule, they differ in their immunological characteristics and clinical associations [28]. Emerging evidence supports the clinical utility of aPS/PT over that of aPT in the setting of APS [29]. A recent systematic review of the topic analyzed available data on more than 7000 patients and controls from 38 studies on aPT and 10 studies on aPS/PT.…”