title: Resistance to annexin A5 anticoagulant activity in women with histories for obstetric antiphospholipid syndrome.
abstract: OBJECTIVE
  The objective of the study was to investigate whether resistance to annexin A5 anticoagulant activity (AnxA5) occurs in women with histories for obstetric complications of antiphospholipid syndrome (Obs-APS) and whether this correlates with antibody recognition of domain 1 of β2-glycoprotein.
  
  
  METHODS
  One hundred thirty-six women with antiphospholipid antibodies, including 70 with histories for Obs-APS and 30 controls, were investigated.
  
  
  RESULTS
  Women with Obs-APS showed resistance to AnxA5 activity (median, 216%; range, 130-282% vs controls; median, 247%; range, 217-283%; P < .0001) and elevated levels of anti-domain I immunoglobulin (Ig) G (optical density: median, 0.056; range, 0.021-0.489 vs median, 0.042; range, 0.020-0.323; P = .002). Those in the lowest tertile of AnxA5 anticoagulant ratios had an odds ratio for Obs-APS of 58.0 (95% confidence interval, 3.3-1021.5). There was an inverse correlation between levels of annexin A5 anticoagulant activity and anti-domain I IgG.
  
  
  CONCLUSIONS
  Resistance to AnxA5 anticoagulant activity is associated with antibody recognition of domain I of β2-glycoprotein I and identifies a subset of women with histories for Obs-APS.
authors.affiliation: Department of Hematology, Guy's and St Thomas's Trust, King's College, London, UK. beverley.hunt@gstt.nhs.uk
authors.forename: Beverley J
authors.initials: BJ
authors.lastname: Hunt
authors.forename: Xiao-Xuan
authors.initials: XX
authors.lastname: Wu
authors.forename: Bas
authors.initials: B
authors.lastname: de Laat
authors.forename: Alan A
authors.initials: AA
authors.lastname: Arslan
authors.forename: Sara
authors.initials: S
authors.lastname: Stuart-Smith
authors.forename: Jacob H
authors.initials: JH
authors.lastname: Rand
mesh_terms: D000328:Adult; D000368:Aged; D017304:Annexin A5 / Q000378:metabolism*; D017152:Antibodies, Antiphospholipid / Q000276:immunology* / Q000378:metabolism; D016736:Antiphospholipid Syndrome / Q000276:immunology* / Q000378:metabolism; D005260:Female; D006801:Humans; D008875:Middle Aged; D011247:Pregnancy; D011248:Pregnancy Complications / Q000276:immunology* / Q000378:metabolism
chemical_list: D017304:Annexin A5; D017152:Antibodies, Antiphospholipid