title: Anticardiolipin antibodies, free protein S levels and thrombosis: a survey in a selected population of rheumatoid arthritis patients.
abstract: OBJECTIVE
  To investigate plasma levels of natural anticoagulant proteins such as protein S, protein C and antithrombin III in a selected population of patients with rheumatoid arthritis (RA) with and without anticardiolipin antibody (aCL) positivity, and to evaluate the possible relationships with an increased risk of thrombotic events in RA.
  
  
  METHODS
  A total of 184 female RA patients attending our Extra-Articular Involvement RA Clinic were evaluated for aCL levels, total and free protein S, protein C and antithrombin III concentrations, and for the occurrence of thrombotic events. Patients were grouped as aCL positive (n = 35) and aCL negative (n = 149).
  
  
  RESULTS
  Higher rates of venous and/or arterial thromboses were diagnosed in patients with RA compared to controls (P = 0.01). In particular, lower free protein S levels were found in aCL-positive patients with RA compared to both aCL-negative patients and controls (P = 0.001). Functional assays for protein C, antithrombin III as well as total protein S levels were found to be in the normal range in all patients and controls.
  
  
  CONCLUSIONS
  The association observed between aCL positivity and decreased levels of free protein S in RA patients may represent one of the risk factors for thrombotic events.
authors.affiliation: Department of Internal Medicine, University of Genoa, Italy.
authors.forename: B
authors.initials: B
authors.lastname: Seriolo
authors.forename: S
authors.initials: S
authors.lastname: Accardo
authors.forename: A
authors.initials: A
authors.lastname: Garnero
authors.forename: D
authors.initials: D
authors.lastname: Fasciolo
authors.forename: M
authors.initials: M
authors.lastname: Cutolo
mesh_terms: D000328:Adult; D000368:Aged; D017153:Antibodies, Anticardiolipin / Q000032:analysis*; D000990:Antithrombin III / Q000032:analysis*; D001172:Arthritis, Rheumatoid / Q000097:blood* / Q000150:complications; D015415:Biomarkers / Q000097:blood; D005260:Female; D006801:Humans; D008875:Middle Aged; D011486:Protein C / Q000032:analysis*; D017293:Protein S / Q000032:analysis*; D012307:Risk Factors; D013927:Thrombosis / Q000209:etiology*
chemical_list: D017153:Antibodies, Anticardiolipin; D015415:Biomarkers; D011486:Protein C; D017293:Protein S; D000990:Antithrombin III