title: Autoantibodies directed against bactericidal/permeability-increasing protein in patients with cystic fibrosis: association with microbial respiratory tract colonization.
abstract: BACKGROUND
  Cystic fibrosis (CF) is associated with the appearance of serum autoantibodies directed against bactericidal/permeability-increasing protein (BPI).
  
  
  OBJECTIVE
  To determine the age-specific seroprevalence rates of anti-BPI-IgG and IgA in a population of patients with CF and to correlate anti-BPI antibody concentrations with microbial respiratory tract colonization and pulmonary function variables at the time of serum sampling and 6 years thereafter.
  
  
  METHODS
  Determination of BPI antibodies of the IgG and IgA isotypes using a commercial enzyme-linked immunosorbent assay in sera of a CF serum bank of 1992; correlation of anti-BPI antibody concentrations with age, clinical score, pulmonary function variables in 1992 and 1998, total serum immunoglobulin isotype concentrations and respiratory tract colonization with Pseudomonas aeruginosa and Aspergillus spp.
  
  
  RESULTS
  Seventy-one patients (age in 1992, 14.1 +/- 7.5 years) were studied. Reactivities for anti-BPI-IgG and IgA were found in 28 (39%) and 26 (37%) patients, respectively. The seroprevalence of anti-BPI-IgA, but not IgG, increased significantly with age. P. aeruginosa colonization was associated with elevated concentrations of anti-BPI-IgG (P = 0.003) and IgA (P = 0.037). There were significant negative correlations between pulmonary function variables (vital capacity, forced expiratory volume in 1 s) in 1992 and 1998, respectively, and concentrations of anti-BPI-IgG or IgA in a multiple regression analysis. Anti-BPI-IgG, but not IgA, remained significantly associated with P. aeruginosa colonization (P = 0.006) and with reduced vital capacity (P = 0.01) in 1998 after correction for total serum isotype concentration.
  
  
  CONCLUSIONS
  Anti-BPI-IgG are strongly associated with concurrent P. aeruginosa colonization and with long term restrictive pulmonary function abnormalities.
authors.affiliation: Department of Pediatrics, University of Bern, Inselspital, Switzerland.
authors.forename: C
authors.initials: C
authors.lastname: Aebi
authors.forename: F
authors.initials: F
authors.lastname: Theiler
authors.forename: C C
authors.initials: CC
authors.lastname: Aebischer
authors.forename: M H
authors.initials: MH
authors.lastname: Schoeni
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D023181:Antimicrobial Cationic Peptides; D001230:Aspergillus / Q000302:isolation & purification; D001323:Autoantibodies / Q000097:blood*; D001798:Blood Proteins / Q000276:immunology*; D003550:Cystic Fibrosis / Q000150:complications / Q000276:immunology* / Q000401:mortality; D005260:Female; D006801:Humans; D007070:Immunoglobulin A / Q000097:blood / Q000276:immunology; D007074:Immunoglobulin G / Q000097:blood / Q000276:immunology; D008297:Male; D008565:Membrane Proteins; D011550:Pseudomonas aeruginosa / Q000302:isolation & purification; D012141:Respiratory Tract Infections / Q000209:etiology / Q000276:immunology* / Q000382:microbiology; D016036:Seroepidemiologic Studies
chemical_list: D023181:Antimicrobial Cationic Peptides; D001323:Autoantibodies; D001798:Blood Proteins; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D008565:Membrane Proteins; C021623:bactericidal permeability increasing protein