title: Factor XII autoantibodies as a novel marker for thrombosis and adverse obstetric history in patients with systemic lupus erythematosus.
abstract: OBJECTIVE
  To investigate the clinical significance of anti-factor XII (FXII) in a large cohort of patients with systemic lupus erythematosus (SLE).
  
  
  METHODS
  This study comprised 127 patients with SLE. IgG and IgM anti-FXII were tested by an in-house ELISA. 123 healthy donors comprised the control group.
  
  
  RESULTS
  51 (40%) patients with SLE and 9 (7%) healthy controls were positive for anti-FXII. IgG and IgM anti-FXII were frequently found in patients with thrombosis (28% and 13%, respectively). Levels of IgG and IgM anti-FXII were higher in patients with thrombosis than in the control group (p<0.001 and p=0.005, respectively). Anti-FXII was more frequent in patients with arterial thrombosis (31% vs 4% for IgG and 14% vs 3% for IgM, respectively) and venous thrombosis than in controls (37% vs 4% for IgG). IgG anti-FXII were more frequent in patients with miscarriages and fetal death (35% and 40% vs 4% for IgM). The prevalence of IgM anti-FXII was not different between groups.
  
  
  CONCLUSIONS
  Anti-FXII are frequent in patients with SLE. Their presence is associated with thrombosis and adverse obstetric history, making these antibodies a novel marker for the antiphospholipid syndrome.
authors.affiliation: Lupus Research Unit, The Rayne Institute, King's College London School of Medicine at Guy's, King's and St Thomas' Hospitals, London SE1 7EH, UK. maria.bertolaccini@kcl.ac.uk
authors.forename: Maria Laura
authors.initials: ML
authors.lastname: Bertolaccini
authors.forename: Kirti
authors.initials: K
authors.lastname: Mepani
authors.forename: Giovanni
authors.initials: G
authors.lastname: Sanna
authors.forename: Graham R V
authors.initials: GR
authors.lastname: Hughes
authors.forename: Munther A
authors.initials: MA
authors.lastname: Khamashta
mesh_terms: D000022:Abortion, Spontaneous / Q000209:etiology / Q000276:immunology; D000328:Adult; D016736:Antiphospholipid Syndrome / Q000175:diagnosis* / Q000209:etiology; D001323:Autoantibodies / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005174:Factor XII / Q000276:immunology*; D005260:Female; D005313:Fetal Death / Q000209:etiology / Q000276:immunology; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D007075:Immunoglobulin M / Q000097:blood; D016682:Lupus Coagulation Inhibitor / Q000097:blood; D008180:Lupus Erythematosus, Systemic / Q000150:complications* / Q000276:immunology; D008297:Male; D008875:Middle Aged; D011247:Pregnancy; D011256:Pregnancy Outcome; D013927:Thrombosis / Q000209:etiology / Q000276:immunology
chemical_list: D001323:Autoantibodies; D015415:Biomarkers; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D016682:Lupus Coagulation Inhibitor; D005174:Factor XII