title: BF*F allotype of the alternative pathway of complement: A marker of protection against the development of antiphospholipid antibodies in patients with systemic lupus erythematosus.
abstract: BACKGROUND
  B factor (BF) from the alternative complement pathway seems to participate in the pathophysiology of systemic lupus erythematosus (SLE) and antiphospholipid syndrome (APS).
  
  
  OBJECTIVE
  To study the allotypic variability of BF in SLE and their associations with clinical and autoantibodies profile.
  
  
  METHODS
  BF allotypes were determined by high-voltage agarose gel electrophoresis, under constant cooling, followed by immunofixation with anti-human BF antibody, in 188 SLE patients and 103 controls. Clinical and serological data were obtained from medical examination and records.
  
  
  RESULTS
  No significant differences of BF variants between patients and controls were found, neither in relation to epidemiologic or clinical manifestations. Associations of phenotype BF SS07 and allotype BF*S07 were found with anticardiolipin IgM (aCl-IgM) antibodies (p = 0.014 and p = 0.009 respectively), but not with aCl-IgG, lupus anticoagulant (LA), anti β2GPI or clinical APS. A significant decrease in BF*F allotype (p = 0.043) and BF SF phenotype (p = 0.018) was detected in patients with anti-phospholipid antibodies as a whole (aCl-IgG, aCl-IgM, LA and anti β2GPI).
  
  
  CONCLUSIONS
  There is a link between phenotype BF SS07 and allotype BF*S07 with aCl-IgM in SLE patients; BF*F allotype could be considered a marker of protection against the development of antiphospholipid antibodies in these patients.
authors.affiliation: Laboratory of Immunopathology, Federal University of Paraná, Brazil.
authors.forename: V F
authors.initials: VF
authors.lastname: Picceli
authors.affiliation: Rheumatology Unit, Evangelic University Hospital of Curitiba, Curitiba, Brazil.
authors.forename: T L
authors.initials: TL
authors.lastname: Skare
authors.affiliation: Department of Medicine, Positivo University Curitiba, Curitiba, Brazil.
authors.forename: R M
authors.initials: RM
authors.lastname: Nisihara
authors.affiliation: Laboratory of Immunopathology, Federal University of Paraná, Brazil.
authors.forename: F R
authors.initials: FR
authors.lastname: Nass
authors.affiliation: Laboratory of Immunopathology, Federal University of Paraná, Brazil.
authors.forename: I T
authors.initials: IT
authors.lastname: Messias-Reason
authors.affiliation: Laboratory of Immunopathology, Federal University of Paraná, Brazil Department of Clinical Analysis, Federal University of Paraná, Curitiba, Brazil shirley@ufpr.br.
authors.forename: S R R
authors.initials: SR
authors.lastname: Utiyama
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D017153:Antibodies, Anticardiolipin / Q000097:blood; D017152:Antibodies, Antiphospholipid / Q000097:blood*; D016736:Antiphospholipid Syndrome / Q000097:blood / Q000235:genetics / Q000276:immunology / Q000517:prevention & control*; D015415:Biomarkers / Q000097:blood; D016022:Case-Control Studies; D011415:Complement Factor B / Q000235:genetics / Q000276:immunology*; D003170:Complement Pathway, Alternative; D004587:Electrophoresis, Agar Gel; D005260:Female; D005787:Gene Frequency; D006801:Humans; D007075:Immunoglobulin M / Q000097:blood; D008180:Lupus Erythematosus, Systemic / Q000097:blood / Q000235:genetics / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D010641:Phenotype; D011110:Polymorphism, Genetic; D011237:Predictive Value of Tests; D065840:Protective Factors; D012307:Risk Factors; D055815:Young Adult
chemical_list: D017153:Antibodies, Anticardiolipin; D017152:Antibodies, Antiphospholipid; D015415:Biomarkers; D007075:Immunoglobulin M; D011415:Complement Factor B
keywords: Anticardiolipin antibodies; antiphospholipid syndrome; lupus anticoagulant; systemic lupus erythematosus