Circulating complexes containing IgA and fibronectin in patients with primary IgA nephropathy

Proc Natl Acad Sci U S A. 1988 Jul;85(13):4865-8. doi: 10.1073/pnas.85.13.4865.

Abstract

IgA antibodies from patients with primary IgA nephropathy bind to collagens I, II, and IV. Here we show that this binding is mediated by the collagen-binding site of fibronectin, which occurs in the circulation in complex with IgA. No antibodies binding directly to collagen were identified. The complexes were isolated by affinity chromatography on gelatin-Sepharose and heparin-Sepharose, both with affinity for fibronectin, followed by adsorption to anti-human IgA immobilized on agarose gel. The presence of fibronectin and IgA antibodies in the isolated complexes is shown by enzyme-linked immunosorbent assay, gel electrophoresis, and electrophoretic transfer followed by immunostaining. The presence of an IgA-fibronectin complex in serum and the binding of this complex to collagen demonstrate the necessity of removing fibronectin from serum prior to identifying anti-collagen antibodies.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adsorption
  • Antibody Specificity
  • Antigen-Antibody Complex / analysis*
  • Autoantibodies / immunology*
  • Binding Sites
  • Chromatography, Affinity
  • Collagen / metabolism*
  • Fibronectins / immunology*
  • Fibronectins / metabolism
  • Gelatin
  • Glomerulonephritis, IGA / immunology*
  • Heparin
  • Humans
  • Immunoglobulin A / immunology*
  • Immunoglobulin A / metabolism
  • Sepharose

Substances

  • Antigen-Antibody Complex
  • Autoantibodies
  • Fibronectins
  • Immunoglobulin A
  • Gelatin
  • Heparin
  • Collagen
  • Sepharose