Thromb Haemost 1996; 75(04): 555-559
DOI: 10.1055/s-0038-1650320
Original Article
Schattauer GmbH Stuttgart

Inhibition of Protein S by Autoantibodies in Patients with Acquired Protein S Deficiency

M Sorice
1   The Dipartimento di Medicina Sperimentale e Patologia, Università degli Studi di Roma “La Sapienza”, Rome
,
P Arcieri
2   Centro Trombosi, Dipartimento di Biopatologia Umana, Università degli Studi di Roma “La Sapienza”, Rome
,
T Griggi
1   The Dipartimento di Medicina Sperimentale e Patologia, Università degli Studi di Roma “La Sapienza”, Rome
,
A Circella
1   The Dipartimento di Medicina Sperimentale e Patologia, Università degli Studi di Roma “La Sapienza”, Rome
,
R Misasi
1   The Dipartimento di Medicina Sperimentale e Patologia, Università degli Studi di Roma “La Sapienza”, Rome
,
L Lenti
1   The Dipartimento di Medicina Sperimentale e Patologia, Università degli Studi di Roma “La Sapienza”, Rome
,
G D Di Nucci
2   Centro Trombosi, Dipartimento di Biopatologia Umana, Università degli Studi di Roma “La Sapienza”, Rome
,
G Mariani
3   Cattedra di Ematologia, Universita degli Studi di Palermo, Italy
› Author Affiliations
Further Information

Publication History

Received 31 May 1995

Accepted after resubmission 18 December 1995

Publication Date:
10 July 2018 (online)

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Summary

This study was undertaken to analyze antibodies to protein S (PS) in patients with an acquired PS deficiency. Plasma from symptomatic patients with acquired (n = 14) or congenital (n = 10) PS deficiency and 10 healthy donors was screened for PS antibodies by immunoblotting and for anti-phospholipid antibodies. PS antibodies (IgG) were detected in five of the patients with acquired PS deficiency. These antibodies belonged to the G1 and G4 immunoglobulin subclasses. IgG fractions from the same 5 patients were shown to inhibit PS activity. The inhibition of PS activity by the 5 IgG fractions was shown to be time-and dose-dependent and was abolished following incubation with purified PS, while no effect was found after absorption with cardiolipin micelles. In addition, anticardiolipin monoclonal or human purified antibodies, failed to exert significant PS inhibition. These findings demonstrate that anti-PS antibodies are able to inhibit PS activity and that this is independent of anti-phospholipid antibodies. Given the clinical features of the patients, these antibodies should be regarded as an expression of the broad autoimmune syndrome involving the phospholipid-binding plasma proteins.