Binding of bacterial endotoxins to the macrophage surface: visualization by fracture-flip and immunocytochemistryC Risco and P Pinto da Silva Mathematical Biology Department, National Cancer Institute, Frederick Cancer Research and Development Center, Maryland 21702-1201. Endotoxins (lipopolysaccharides, LPS) are surface components of gram- negative bacteria that stimulate macrophage activation and cause endotoxic shock. How LPS is recognized by host cells is still an open question, but it is generally accepted that many effects of endotoxins follow the overproduction of cytokines by macrophages. In the present study, we used fracture-flip and immunolabeling to study the morphology of isolated commercial LPS (C-LPS), the endotoxin release from the bacterial wall in presence of serum (S-LPS), and the distribution of these two endotoxins on the macrophage surface. Cells treated with C- LPS exhibited large LPS aggregates bound to smooth and particulate areas of the membrane and to microvilli. In contrast, macrophages incubated with S-LPS showed a uniform monodispersed labeling over the free surface of the membrane. Our results show that fracture-flip provides high-resolution images of the binding of ligands to the cell surface. They also suggest the importance of using highly dispersed LPS suspensions when the mechanisms of cell activation and damage by endotoxins are studied.
Volume 41,
Issue 4,
pp. 601-608,
04/01/1993
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R. L. Kitchens, P.-y. Wang, and R. S. Munford Bacterial Lipopolysaccharide Can Enter Monocytes Via Two CD14-Dependent Pathways J. Immunol., November 15, 1998; 161(10): 5534 - 5545. [Abstract] [Full Text] [PDF] |
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C Risco, L Menendez-Arias, T. Copeland, P Pinto da Silva, and S Oroszlan Intracellular transport of the murine leukemia virus during acute infection of NIH 3T3 cells: nuclear import of nucleocapsid protein and integrase J. Cell Sci., January 9, 1995; 108(9): 3039 - 3050. [Abstract] [PDF] |
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