Sialoadhesin expression by bone marrow macrophages derived from Ehrlich-tumor-bearing mice.

Abstract

Sialoadhesin (sheep erythrocyte receptor, SER) is a macrophage-restricted adhesion molecule that binds certain sialylated ligands. It is borne by bone marrow stromal macrophages, promoting the interaction with developing myeloid cells, and by a subset of tissue macrophages involved in antigen presentation and activation of tumor-reactive T cells. The expression of sialoadhesin on SER+ macrophages is not constitutive but requires the continuous supply of a sialoadhesin-inducing serum factor. Tumor growth is often associated with marked alterations of myelopoiesis and impairment of T cell activation; yet the expression of sialoadhesin in macrophages derived from tumor bearers has not been addressed. The aim of this study was to assess whether Ehrlich tumor (ET) - a murine mammary carcinoma - growth may modify the sialoadhesin expression by bone marrow macrophages and/or sialoadhesin-inducing activity in ET-bearing sera. Moreover, putative functional sialoadhesin inhibitors produced by ET cells were tested. The results indicate that bone marrow cells from ET bearers show a seven- to eight-fold decrease in SER+ cells as detected by flow cytometry. This is accompanied by an overall decrease in sheep erythrocyte binding to tumor-bearer-derived bone marrow cells, but also by lower numbers of plastic-adherent cells. Functional sialoadhesin expression is preserved at the single-cell level and no inhibitors are found in ET-bearing sera or ET cell culture supernatants. Tumor progression does not impair the sialoadhesin-inducing activity of ET-bearing sera, or the ability of SER- macrophages (e.g. peritoneal macrophages) to respond to such an induction. In conclusion, while SER+ macrophages are greatly decreased in bone marrow from ET bearers, this is not due to a down-regulation of sialoadhesin expression, nor to an impairment of sialoadhesin-inducing factor or to the presence of sialoadhesin-binding moieties of tumor origin, but, more likely, to a decrease of fully mature macrophages.

• Authors: S Kusmartsev, J M Ruiz de Morales, J Rullas, M G Danilets, J L Subiza
• Journal: Cancer immunology, immunotherapy : CII (Cancer Immunol Immunother) Vol. 48 Issue 9 Pg. 493-8 (Dec 1999) ISSN: 0340-7004 [Print] Germany
• PMID: 10602886 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Culture Media, Conditioned
• Membrane Glycoproteins
• Neoplasm Proteins
• Plastics
• Receptors, Immunologic
• Sialic Acid Binding Ig-like Lectin 1
• Siglec1 protein, mouse

Topics

• Animals
• Bone Marrow Cells (metabolism, pathology)
• Carcinoma, Ehrlich Tumor (blood)
• Cell Adhesion
• Cells, Cultured
• Culture Media, Conditioned (pharmacology)
• Disease Progression
• Macrophages (metabolism, pathology)
• Macrophages, Peritoneal (metabolism)
• Membrane Glycoproteins (biosynthesis, genetics)
• Mice
• Mice, Inbred C57BL
• Neoplasm Proteins (biosynthesis, genetics)
• Plastics
• Receptors, Immunologic (biosynthesis, genetics)
• Rosette Formation
• Sialic Acid Binding Ig-like Lectin 1