Original Article

Immunology and Cell Biology (1998) 76, 237–244; doi:10.1046/j.1440-1711.1998.00748.x

Structurally well-defined macrophage activating factor derived from vitamin D3-binding protein has a potent adjuvant activity for immunization

Nobuto Yamamoto1,2 and Venkateswara R Naraparaju1

  1. 1 Laboratory of Cancer Immunology and Molecular Biology, Albert Einstein Cancer Center and
  2. 2 Socrates Institute for Therapeutic Immunology, Philadelphia, Pennsylvania, USA

Correspondence: N Yamamoto, Albert Einstein Cancer Center, Korman Research Pavilion B-31, 5501 Old York Road, Philadelphia, PA 19141, USA.

Received 13 March 1998; Accepted 23 March 1998.

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Abstract

Freund's adjuvant produced severe inflammation that augments development of antibodies. Thus, mixed administration of antigens with adjuvant was not required as long as inflammation was induced in the hosts. Since macrophage activation for phagocytosis and antigen processing is the first step of antibody development, inflammation-primed macrophage activation plays a major role in immune development. Therefore, macrophage activating factor should act as an adjuvant for immunization. The inflammation-primed macrophage activation process is the major macrophage activating cascade that requires participation of serum vitamin D3-binding protein (DBP; human DBP is known as Gc protein) and glycosidases of B and T lymphocytes. Stepwise incubation of Gc protein with immobilized beta-galactosidase and sialidase efficiently generated the most potent macrophage activating factor (designated GcMAF) we have ever encountered. Administration of GcMAF (20 or 100 pg/mouse) resulted in stimulation of the progenitor cells for extensive mitogenesis and activation of macrophages. Administration of GcMAF (100 pg/mouse) along with immunization of mice with sheep red blood cells (SRBC) produced a large number of anti-SRBC antibody secreting splenic cells in 2–4 days. Thus, GcMAF has a potent adjuvant activity for immunization. Although malignant tumours are poorly immunogenic, 4 days after GcMAF-primed immunization of mice with heat-killed Ehrlich ascites tumour cells, the ascites tumour was no longer transplantable in these mice.

Keywords:

adjuvant, antibody secretion, inflammation, macrophage activating factor, macrophage activation, mitogenesis, progenitor, vitamin D3-binding protein