title: Vitamin D-binding protein (group-specific component) is the sole serum protein required for macrophage activation after treatment of peritoneal cells with lysophosphatidylcholine.
abstract: In vitro treatment of mouse peritoneal cells with 1 micrograms lysophosphatidylcholine (lyso-Pc)/mL in serum free-0.1% egg albumin-supplemented RPMI 1640 medium for 30 min, followed by 3 h cultivation in a medium supplemented with human serum, resulted in a greatly enhanced Fc-receptor-mediated phagocytic activity of macrophages. Vitamin D-binding protein (group-specific component [Gc]) of alpha 2-globulin fraction was shown to be the sole serum glycoprotein required for the generation of a potent macrophage-activating factor. When a mixture of lysophosphatidylcholine (lyso-Pc)-treated nonadherent and adherent cells were cultured in a medium supplemented with a small amount of purified Gc protein (1 ng/mL), a greatly enhanced activation of macrophages was demonstrated. The generation of macrophage-activating factor from purified Gc protein was far more efficient than that from whole serum, indicating that a serum component is inhibitory to the activation process of macrophages. While three other major serum glycoproteins (alpha 2-macroglobulin, alpha 2-HS-glycoprotein and haptoglobin) were neither stimulatory nor inhibitory to lyso-Pc-primed macrophage activation, serum albumin (competitively with Gc protein) appeared to be inhibitory to the process of macrophage activation.
authors.affiliation: 1st Department of Internal Medicine, Jikei University, Tokyo, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Homma
authors.forename: M
authors.initials: M
authors.lastname: Yamamoto
authors.forename: N
authors.initials: N
authors.lastname: Yamamoto
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D003470:Culture Media; D005260:Female; D006801:Humans; D008244:Lysophosphatidylcholines / Q000276:immunology*; D008262:Macrophage Activation / Q000276:immunology*; D016215:Macrophage-Activating Factors / Q000096:biosynthesis; D008264:Macrophages / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D010529:Peritoneal Cavity / Q000166:cytology; D010587:Phagocytosis / Q000276:immunology; D011817:Rabbits; D012709:Serum Albumin / Q000276:immunology; D014809:Vitamin D-Binding Protein / Q000276:immunology*
chemical_list: D003470:Culture Media; D008244:Lysophosphatidylcholines; D016215:Macrophage-Activating Factors; D012709:Serum Albumin; D014809:Vitamin D-Binding Protein