title: Cholesterol crystal binding of biliary immunoglobulin A: visualization by fluorescence light microscopy.
abstract: OBJECTIVE
  To assess potential contributions of biliary IgA for crystal agglomeration into gallstones, we visualized cholesterol crystal binding of biliary IgA.
  
  
  METHODS
  Crystal binding biliary proteins were extracted from human gallbladder bile using lectin affinity chromatography.Biliary IgA was isolated from the bound protein fraction by immunoaffinity chromatography. Pure cholesterol monohydrate crystals were incubated with biliary IgA and fluoresceine isothiocyanate (FITC)conjugated anti IgA at 37 degree. Samples were examined under polarizing and fluorescence light microscopy with digital image processing.
  
  
  RESULTS
  Binding of biliary IgA to cholesterol monohydrate crystals could be visualized with FITC conjugated anti IgA antibodies. Peak fluorescence occurred at crystal edges and dislocations. Controls without biliary IgA or with biliary IgG showed no significant fluorescence.
  
  
  CONCLUSIONS
  Fluorescence light microscopy provided evidence for cholesterol crystal binding of biliary IgA. Cholesterol crystal binding proteins like IgA might be important mediators of crystal agglomeration and growth of cholesterol gallstones by modifying the evolving crystal structures in vivo.
authors.affiliation: Department of Medicine III, RWTH Aachen, Pauwelsstra betae 30, 52057 Aachen,Germany.
authors.forename: F
authors.initials: F
authors.lastname: Lammert
authors.forename: S
authors.initials: S
authors.lastname: Südfeld
authors.forename: N
authors.initials: N
authors.lastname: Busch
authors.forename: S
authors.initials: S
authors.lastname: Matern
mesh_terms: D001646:Bile / Q000378:metabolism*; D002769:Cholelithiasis / Q000378:metabolism*; D002784:Cholesterol / Q000378:metabolism*; D002846:Chromatography, Affinity; D003460:Crystallization; D005455:Fluorescent Antibody Technique; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007071:Immunoglobulin A, Secretory / Q000378:metabolism*; D008856:Microscopy, Fluorescence
chemical_list: D007071:Immunoglobulin A, Secretory; D002784:Cholesterol