title: Serum IgA reactivity against GroEL of Streptococcus sanguinis and human heterogeneous nuclear ribonucleoprotein A2/B1 in patients with Behçet disease.
abstract: BACKGROUND
  Infectious agents, especially Streptococcus sanguinis and herpes simplex virus, have long been postulated as major triggering factors for Behçet disease (BD).
  
  
  OBJECTIVE
  To identify an anti-S. sanguinis antigen reacting with serum IgA antibody in patients with BD.
  
  
  METHODS
  We detected a target protein by proteomics analysis and evaluated serum IgA reactivity of 100 patients with BD against the identified streptococcal target protein and human heterogeneous nuclear ribonucleoprotein (hnRNP) A2/B1. Homologous epitope sequences between the streptococcal target protein and human hnRNP A2/B1 were also evaluated.
  
  
  RESULTS
  Four protein bands were detected by immunoprecipitation, and chaperonin GroEL was identified by a proteomics analysis. Reactivity of serum IgA against recombinant S. sanguinis GroEL was detected in 77 of 100 patients with BD (77%) and in 21 of 70 healthy controls (30%). In addition, reactivity of serum IgA against human recombinant hnRNP A2/B1 was seen in 79 of 100 patients with BD (79%) and in eight of 70 healthy controls (11%). Among the eight distinctive epitopes with significant homology between S. sanguinis GroEL and human hnRNP A2/B1, the serum IgA reactivity of patients with BD was markedly higher with epitope 3 (hnRNP A2/B1 peptide 33-46 and GroEL peptide 57-70) and epitope 6 (hnRNP A2/B1 peptide 177-188 and GroEL peptide 347-358).
  
  
  CONCLUSIONS
  We identified an S. sanguinis GroEL protein as a target of serum anti-S. sanguinis IgA antibody reactivity in patients with BD. In addition, patients with BD exhibited serum IgA reactivity against homologous epitope regions between S. sanguinis GroEL and human hnRNP A2/B1.
authors.affiliation: Department of Dermatology and Cutaneous Biology Research Institute, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: S B
authors.initials: SB
authors.lastname: Cho
authors.forename: Z
authors.initials: Z
authors.lastname: Zheng
authors.forename: K J
authors.initials: KJ
authors.lastname: Ahn
authors.forename: M J
authors.initials: MJ
authors.lastname: Choi
authors.forename: S
authors.initials: S
authors.lastname: Cho
authors.forename: D-Y
authors.initials: DY
authors.lastname: Kim
authors.forename: H S
authors.initials: HS
authors.lastname: Lee
authors.forename: D
authors.initials: D
authors.lastname: Bang
mesh_terms: D000328:Adult; D001426:Bacterial Proteins / Q000276:immunology*; D001528:Behcet Syndrome / Q000209:etiology / Q000276:immunology*; D016022:Case-Control Studies; D018834:Chaperonin 60 / Q000276:immunology*; D000939:Epitopes / Q000276:immunology; D005260:Female; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B / Q000276:immunology*; D006801:Humans; D007070:Immunoglobulin A / Q000097:blood*; D047468:Immunoprecipitation / Q000379:methods; D008297:Male; D008875:Middle Aged; D013298:Streptococcus sanguis / Q000276:immunology*
chemical_list: D001426:Bacterial Proteins; D018834:Chaperonin 60; D000939:Epitopes; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B; D007070:Immunoglobulin A