Human C4-binding protein. Association with immune complexes in vitro and in vivo

J Clin Invest. 1979 Mar;63(3):437-42. doi: 10.1172/JCI109320.


C4-binding protein (bp), a glycoprotein with specific binding affinity for the activated form of C4 (C4b), has recently been isolated from human serum and partially characterized. This report demonstrates that C4-bp is incorporated into soluble immune complexes after complement activation in vitro. The reaction requires Ca++ ions and the presence of C4 in serum. Immunopathological studies of various forms of glomerulonephritis revealed intense C4-bp deposition in glomeruli from patients with immune-complex type of pathogenesis. C4-bp deposition was in close correlation with that of C4. These observations, together with the in vitro association of C4-bp to immune complexes, support the notion that the deposits in glomeruli represent the local accumulation of immune complexes.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Antigen-Antibody Complex*
  • Blood Proteins / immunology*
  • Carrier Proteins / blood
  • Carrier Proteins / immunology*
  • Complement C4 / metabolism*
  • Fluorescent Antibody Technique
  • Glomerulonephritis / immunology
  • Glycoproteins / blood
  • Glycoproteins / immunology*
  • Humans
  • Immune Complex Diseases / immunology
  • In Vitro Techniques


  • Antigen-Antibody Complex
  • Blood Proteins
  • Carrier Proteins
  • Complement C4
  • Glycoproteins