title: Activated protein C resistance in patients with anti-beta 2 glycoprotein I antibodies.
abstract: To evaluate if the presence of anti-beta 2GPI antibodies (a beta 2GPI) is associated with activated protein C resistance (APC-R) phenotype, we performed the APC-R APTT-based assay in 74 plasma samples from patients with antiphospholipid antibodies (aPL). Samples were diluted 1:5 in factor V-deficient plasma. Lupus anticoagulant (LA), anticardiolipin antibodies (aCL) and a beta 2GPI (IgG and IgM) were also performed. A control group of 22 healthy volunteers was used. The prevalence of reduced APC-R ratio in patients with aPL was significantly higher than in normal controls (31.1 vs 4.5%, P < 0.05) and the mean APC-R ratio was lower (mean +/- SD; 2.32 +/- 0.40 vs 2.55 +/- 0.21, P < 0.02). There were no differences in the prevalence of APC-R and the ratio values between LA(+) and LA(-). Among the LA(+), the aCL(+) had a higher prevalence of APC-R than the aCL(-) (P < 0.01) and lower APC-R ratios (P < 0.01). The latter group was no different to normal controls. Anti-beta 2GPI antibodies were associated with a higher prevalence of APC-R (50.0 vs 19.6%, P < 0.001), and lower APC-R ratios (2.15 +/- 0.41 vs 2.42 +/- 0.35, P < 0.005), compared with a beta 2GPI(-). In conclusion, the acquired APC-R in patients with aPL seems to be associated with aCL and a beta 2GPI rather than an in vitro interference by LA.
authors.affiliation: University Institute of Biomedical Sciences, Buenos Aires, Argentina.
authors.forename: M
authors.initials: M
authors.lastname: Martinuzzo
authors.forename: R
authors.initials: R
authors.lastname: Forastiero
authors.forename: Y
authors.initials: Y
authors.lastname: Adamczuk
authors.forename: G
authors.initials: G
authors.lastname: Cerrato
authors.forename: L O
authors.initials: LO
authors.lastname: Carreras
mesh_terms: D017153:Antibodies, Anticardiolipin / Q000097:blood; D016736:Antiphospholipid Syndrome / Q000097:blood / Q000276:immunology; D001323:Autoantibodies / Q000097:blood*; D004351:Drug Resistance; D004789:Enzyme Activation; D005260:Female; D006023:Glycoproteins / Q000276:immunology*; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D016682:Lupus Coagulation Inhibitor / Q000097:blood; D008297:Male; D011486:Protein C / Q000378:metabolism*; D053482:beta 2-Glycoprotein I
chemical_list: D017153:Antibodies, Anticardiolipin; D001323:Autoantibodies; D006023:Glycoproteins; D007074:Immunoglobulin G; D016682:Lupus Coagulation Inhibitor; D011486:Protein C; D053482:beta 2-Glycoprotein I