Arthritis & Rheumatism, Volume 62,
November 2010 Abstract Supplement

Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Atlanta, Georgia November 6-11, 2010.


Utility of Anti-Phosphatidylserine/Prothrombin and IgA Antiphospholipid Assays in Antiphospholipid Syndrome.

Akhter3,  Ehtisham, Binder2,  Walter L., Shums2,  Zakera, Petri1,  Michelle A.

Timonium, MD
Inova Diagnostics Inc, San Diego, CA
Johns Hopkins University, Baltimore, MD

Purpose:

Currently three antiphospholipid assays are in wide use clinically (lupus anticoagulant, anticardiolipin (aCL), and anti-beta2 glcyoprotein I (anti-beta2 GPI)). The lupus anticoagulant is the most specific assay, conferring the highest risk of thrombosis and pregnancy loss, but it cannot be validly performed in an anticoagulated patient. We investigated anti-phosphatidylserine/prothrombin (anti-PS/PT), which detects most lupus anticoagulants, in terms of its association with thrombosis. We also investigated the utility of IgA assays for APS in SLE.

Methods:

Stored samples from SLE patients with and without past thrombosis were assayed for anti-beta2 GPI (IgG/IgM/IgA), Domain 1 (IgG) and Domain 4/5 (IgA), aCL (IgG/IgM/IgA) and anti-PS/PT (IgG, IgM and IgG/M).

Results:

For any thrombosis, the highest association was with aCL IgA, followed anti-beta2 GPI IgG and anti-beta2 GPI IgA. Anti-PS/PT IgG, IgM and IgG/M were similar (Table 1).

Table 1: Any Thrombosis

 AssayThrombosis(n = 160) Number (% positive)No thrombosis(n = 166)Number (% positive)Odds Ratio 95% CIP-value
IgGbeta2 GPI18 (5.5%)6 (3.6%)3.4 (1.3, 8.7).0083
 beta GPI Domain 111 (6.7%)9 (5.4%)1.3 (0.5, 3.2).5845
 Anticardiolipin22 (13.8%)16 (9.6%)1.5 (0.8, 3.0).2475
 PSPT26 (16.3%)14 (8.4%)2.1 (1.1, 4.2).0315
IgMbeta2 GPI8 (5.0%)9 (5.4%)0.9 (0.3, 2.4).8641
 Anticardiolipin18 (1.3%)15 (9.0%)1.3 (0.6, 2.6).5077
 PSPT42 (26.3%)26 (15.7%)1.9 (1.1, 3.3).0187
IgAbeta2 GPI48 (30.0%)24 (14.5%)2.5 (1.5, 4.4).0007
 Anticardiolipin10 (6.3%)2 (1.2%)5.5 (1.2, 25.4).0156
 beta2 GPI D4/535 (21.9%)28 (16.9%)1.4 (0.8, 2.4).2523
IgG/MPSPT38 (23.8%)24 (14.5%)1.8 (1.0, 3.2).0326

For venous thrombosis, the highest association was again with aCL IgA, followed by anti-beta2 GPI IgG, and then anti-PS/PT IgG and IgG/M (Table 2).

Table 2: Venous Thrombosis

 AssayThrombosis(n = 102) Number (% positive)No thrombosis(n = 224)Number (% positive)Odds Ratio 95% CIP-value
IgGbeta2 GPI15 (14.7%)9 (4.0%)4.1 (1.7, 9.8).0006
 beta2 GPI Domain 19 (8.8%)11 (4.9%)1.9 (0.8, 4.7).1722
 Anticardiolipin17 (16.7%)21 (9.4%)1.9 (1.0, 3.8).0571
 PSPT21 (21.0%)19 (8.5%)2.8 (1.4, 5.5).0020
IgMbeta2 GPI6 (5.9%)11 (4.9%)1.2 (0.4, 3.4).7145
 Anticardiolipin13 (12.8%)20 (8.9%)1.5 (0.7, 3.1).2895
 PSPT27 (26.5%)41 (18.3%)1.6 (0.9, 2.8).0924
IgAbeta2 GPI31 (30.4%)41 (18.3%)1.9 (1.1, 3.3).0147
 Anticardiolipin8 (7.8%)4 (1.8%)4.7 (1.4, 15.9).0111
 beta2GPI D4/520 (19.6%)43 (19.2%)1.0 (0.6, 1.9).9305
IgG/MPSPT29 (28.4%)33 (14.7%)2.3 (1.3, 4.1).0035

For Stroke, the only assay with a significant association was antibeta2 GPI Domain 4/5 (32.7% vs. 17%, OR 2.4, p=0.01)

Conclusion:

The importance of IgA isotypes (beta2GPI, aCL) in secondary antiphospholipid syndrome has not been previously recognized. We also found that IgA antibeta2 glycoprotein domain 4/5 was associated with stroke. Domain 1 IgG is not important in secondary APS. Anti-PS/PT, either IgG or IgG/M, is a promising alternative to coagulation assays to detect the lupus anticoagulant

To cite this abstract, please use the following information:
Akhter, Ehtisham, Binder, Walter L., Shums, Zakera, Petri, Michelle A.; Utility of Anti-Phosphatidylserine/Prothrombin and IgA Antiphospholipid Assays in Antiphospholipid Syndrome. [abstract]. Arthritis Rheum 2010;62 Suppl 10 :14
DOI: 10.1002/art.27784

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