Antibodies against C1q in anti-glomerular basement membrane nephritis

Clin Exp Immunol. 1992 Feb;87(2):256-60. doi: 10.1111/j.1365-2249.1992.tb02984.x.


The prevalence of antibodies against the collagen-like region of the subcomponent of the first component of complement, C1q, was investigated in 11 patients with anti-glomerular basement membrane (GBM) nephritis. Anti-C1q antibodies (anti-C1qAb) were detected in seven patients. IgG anti-C1qAb were found in four and IgA anti-C1qAb in five patients. During follow up of the patients a relationship was observed between the levels of IgG anti-C1qAb and the levels of anti-GBM antibodies (anti-GBMAb). Gelfiltration experiments indicated that both IgG anti-C1qAb as well as IgG anti-GBMAb were monomeric and that binding also occurred with the F(ab')2 fragments of the antibodies. Although anti-C1qAb and anti-GBMAb are both directed against a collagen-like structure, it was demonstrated by means of inhibition experiments that anti-C1qAb and anti-GBMAb are directed against different antigenic sites. Comparison of patients with anti-GBM nephritis with and without anti-C1qAb revealed that there were no differences in disease activity or disease severity. Therefore, the results of this study suggest that anti-C1qAb do not play a direct pathogenetic role in anti-GBM nephritis.

MeSH terms

  • Adult
  • Aged
  • Autoantibodies / immunology*
  • Basement Membrane / immunology*
  • Complement C1q / immunology*
  • Glomerulonephritis / immunology*
  • Humans
  • Kidney Glomerulus / immunology
  • Middle Aged


  • Autoantibodies
  • Complement C1q