Membrane-bound lipoprotein lipase on human monocyte-derived macrophages: localization by immunocolloidal gold technique
| Autor: | Ira J. Goldberg, Theresa M. Vanni, Dean A. Handley, James R. Paterniti, Joseph A. Cornicelli |
|---|---|
| Rok vydání: | 1988 |
| Předmět: |
Very low-density lipoprotein
medicine.drug_class Immunoelectron microscopy Biophysics Triacylglycerol lipase Biology Monoclonal antibody Biochemistry Nitrophenols Endocrinology medicine Cell Adhesion Humans Lipoprotein lipase Macrophages digestive oral and skin physiology nutritional and metabolic diseases Antibodies Monoclonal Molecular biology Immunohistochemistry Lipoprotein Lipase Cell culture Monoclonal biology.protein lipids (amino acids peptides and proteins) Antibody |
| Zdroj: | Biochimica et biophysica acta. 959(3) |
| ISSN: | 0006-3002 |
| Popis: | Macrophages from both rodent and human sources have been shown to produce lipoprotein lipase (LPL), the enzyme activity of which can be measured in culture media and in cellular homogenates. The studies reported here show the presence of LPL on the surface of human monocyte-derived macrophages. An inhibitory monoclonal antibody to human LPL was used for cellular and immunoelectron microscopy studies. This antibody is a competitive inhibitor of LPL hydrolysis of triacylglycerol but does not inhibit LPL hydrolysis of a water-soluble substrate, p-nitrophenyl acetate. Furthermore, when postheparin plasma was mixed with monoclonal antibody prior to gel filtration on 6% agarose, the LPL activity eluted with the lipoproteins and was not inhibited by the antibody. These studies suggest that the antibody recognized the lipid/lipoprotein binding site of the LPL molecule. Membrane-bound LPL was demonstrated on human monocyte-derived macrophages using colloidal gold-protein A to detect the monoclonal antibody to LPL. The surface colloidal gold was randomly distributed with a surface density of 56700 gold particles per cell. Control cells cultured in heparin-containing media (10 units/ml) or cells reacted with anti-hepatic triacylglycerol lipase monoclonal IgG or nonimmune mouse IgG did not exhibit membrane binding of protein A-gold. Macrophages were incubated with control and monoclonal anti-LPL IgGs and 125I-labeled anti-mouse IgG F(ab′)2. Heparin-releasable membrane-bound anti-LPL antibody was demonstrated. These studies demonstrate the presence of LPL on the surface of human monocyte-derived macrophages, such that the LPL is oriented with its lipid-binding portion (recognized by this antibody) exposed. Membrane-associated LPL may be important in the interaction and subsequent uptake of lipid and lipoproteins by macrophages and in the generation of atherosclerotic foam cells. |
| Databáze: | OpenAIRE |
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