Elsevier

Cellular Immunology

Volume 170, Issue 2, 15 June 1996, Pages 161-167
Cellular Immunology

Regular Article
Vitamin D3-Binding Protein as a Precursor for Macrophage Activating Factor in the Inflammation-Primed Macrophage Activation Cascade in Rats

https://doi.org/10.1006/cimm.1996.0148Get rights and content

Abstract

When rat peritoneal nonadherent cells were treated with inflammatory lipid metabolites and cultured with adherent cells in 1% fetal calf serum (FCS) supplemented medium RPMI 1640 (FCS medium) for 3 hr, markedly enhanced phagocytic and superoxide generating capacities of macrophages were observed. Stepwise preparation of conditioned medium of lysophosphatidylcholine (lyso-Pc)-treated B cells and untreated T cells in FCS medium generated a potent macrophage activating factor whereas cultivation of lyso-Pc-treated B cells alone in a 1% adult rat serum supplemented medium efficiently generated the macrophage activating factor. Generation of macrophage activating factor requires a precursor protein, serum vitamin D3-binding protein (DBP), as well as participation of lymphocyte glycosidases. The lyso-Pc-inducible β-galactosidase of B lymphocytes and theNeu-1sialidase of T lymphocytes modified bovine DBP (bDBP) to yield the macrophage activating factor, a protein withN-acetylgalactosamine as the remaining sugar. In contrast, lyso-Pc-inducible β-galactosidase of B cells alone modified rat DBP (rDBP) to yield the macrophage activating factor, a protein withN-acetylgalactosamine as the remaining sugar. Thus, we conclude that bDBP carries a trisaccharide composed ofN-acetylgalactosamine, galactose, and sialic acid while rDBP carries a disaccharide composed ofN-acetylgalactosamine and galactose.

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This investigation was supported in part by U.S. PHS Grant AI-32140 to N.Y.

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To whom correspondence and reprint requests should be addressed at Laboratory of Cancer Immunology and Molecular Biology, Albert Einstein Cancer Center, Korman Research Pavilion, 5501 Old York Roads, Philadelphia, PA 19141.

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