title: Free protein S deficiency may be found in patients with antiphospholipid antibodies who do not have systemic lupus erythematosus.
abstract: In order to determine if there is a relationship between antiphospholipid antibodies and reduced free protein S levels, we evaluated 21 patients who had an antiphospholipid antibody but had neither a history of venous thromboembolism nor systemic lupus erythematosus (cases) and 55 matched controls, who did not have an antiphospholipid antibody, a history of thrombosis or systemic lupus erythematosus. Cases and controls had similar protein C and antithrombin levels. Six of 21 cases had reduced free protein S antigen levels, compared to 5 of 55 controls (chi 2 = 5.823 p < 0.025). In addition, the mean free protein S level was significantly lower in cases than in controls (0.30 +/- 0.09 units vs 0.39 +/- 0.13 units, p < 0.01, two-tailed Student's t-test). We conclude that antiphospholipid antibodies are associated with a significant decrease in free protein S levels, and that this acquired free protein S deficiency may contribute to the thrombotic diathesis seen in patients with antiphospholipid antibodies.
authors.affiliation: Department of Medicine, McMaster University, Hamilton, Ontario, Canada.
authors.forename: M A
authors.initials: MA
authors.lastname: Crowther
authors.forename: M
authors.initials: M
authors.lastname: Johnston
authors.forename: J
authors.initials: J
authors.lastname: Weitz
authors.forename: J S
authors.initials: JS
authors.lastname: Ginsberg
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017153:Antibodies, Anticardiolipin / Q000032:analysis; D017152:Antibodies, Antiphospholipid / Q000032:analysis*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D016682:Lupus Coagulation Inhibitor / Q000032:analysis; D008180:Lupus Erythematosus, Systemic; D008875:Middle Aged; D018455:Protein S Deficiency / Q000209:etiology / Q000276:immunology*; D011655:Pulmonary Embolism / Q000097:blood / Q000276:immunology; D013924:Thrombophlebitis / Q000097:blood / Q000276:immunology
chemical_list: D017153:Antibodies, Anticardiolipin; D017152:Antibodies, Antiphospholipid; D016682:Lupus Coagulation Inhibitor