Preparation of Gc protein-derived macrophage activating factor (GcMAF) and its structural characterization and biological activities

Anticancer Res. 2002 Nov-Dec;22(6C):4297-300.


Background: Gc protein has been reported to be a precursor of Gc protein-derived macrophage activation factor (GcMAF) in the inflammation-primed macrophage activation cascade. An inducible beta-galactosidase of B cells and neuraminidase of T cells convert Gc protein to GcMAF.

Materials and methods: Gc protein from human serum was purified using 25(OH)D3 affinity column chromatography and modified to GcMAF using immobilized glycosidases (beta-galactosidase and neuraminidase) The sugar moiety structure of GcMAF was characterized by lectin blotting by Helix pomatia agglutinin. The biological activities of GcMAF were evaluated by a superoxide generation assay and a phagocytosis assay.

Results: We successfully purified Gc protein from human serum. GcMAF was detected by lectin blotting and showed a high biological activity.

Conclusion: Our results support the importance of the terminal N-acetylgalactosamine moiety in the GcMAF-mediated macrophage activation cascade, and the existence of constitutive GcMAF in human serum. These preliminary data are important for designing small molecular GcMAF mimics.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Blotting, Western
  • Chromatography, Affinity
  • Humans
  • Macrophage Activation / drug effects
  • Macrophage-Activating Factors / chemistry*
  • Macrophage-Activating Factors / metabolism
  • Macrophage-Activating Factors / pharmacology*
  • Macrophages, Peritoneal / drug effects
  • Macrophages, Peritoneal / metabolism
  • Mice
  • Neuraminidase / chemistry
  • Neuraminidase / metabolism
  • Superoxides / metabolism
  • Vitamin D-Binding Protein / blood
  • Vitamin D-Binding Protein / chemistry*
  • Vitamin D-Binding Protein / isolation & purification
  • Vitamin D-Binding Protein / metabolism
  • Vitamin D-Binding Protein / pharmacology*
  • beta-Galactosidase / chemistry
  • beta-Galactosidase / metabolism


  • Macrophage-Activating Factors
  • Vitamin D-Binding Protein
  • vitamin D-binding protein-macrophage activating factor
  • Superoxides
  • Neuraminidase
  • beta-Galactosidase