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Surface charge of resident, elicited, and activated mouse peritoneal macrophages
Abstract:
The surface charge of resident, thioglycollate-elicited, and Trypanosoma cruzi-activated mouse peritoneal macrophages was analyzed using cell electrophoresis. All macrophages had a net negative surface charge. Activated macrophages had a lower zeta potential and a higher isoelectrophoretic point than resident and elicited macrophages. The populations of resident, elicited, and activated macrophages were heterogeneous in terms of surface charge. The analysis of the effect of the pH of the solution in which the macrophages were suspended on their cellular electrophoretic mobility (EPM) indicated that their surface contained both positively and negatively charged dissociating groups. The contribution of sialic acid residues to the surface charge was determined by analyzing the effect of neuraminidase treatment on the EPM of the cells. Activated macrophages possessed more sialic acid residues exposed on their surface, and sensitive to the neuraminidase from Clostridium perfringens, than resident and elicited macrophages. Treatment of the cells with the neuraminidase from Vibrio cholerae, however, reduced the surface charge of all macrophages in about the same extent. Macrophages had their mean EPM reduced when incubated in the presence of Ca++, suggesting that some cell surface anionogenic sites have Ca++-binding capacity.
Insights
Macrophages, immune cells, exhibit varying surface charges. Activated macrophages show distinct surface properties, including increased sialic acid residues, impacting their function and interaction.
Area of Science:
- Immunology
- Cell Biology
- Biophysics
Background:
- Macrophages are key immune cells with diverse functions.
- Cell surface properties, like charge, influence macrophage behavior.
- Trypanosoma cruzi activation alters macrophage characteristics.
Purpose of the Study:
- To analyze and compare the surface charge of different mouse peritoneal macrophage populations.
- To investigate the role of sialic acid residues and Ca++ binding in macrophage surface charge.
Main Methods:
- Cell electrophoresis was used to measure electrophoretic mobility (EPM) and zeta potential.
- Macrophage populations analyzed included resident, thioglycollate-elicited, and T. cruzi-activated.
- Neuraminidase treatment and varying pH solutions were employed to probe surface components.
Main Results:
- All macrophages displayed a net negative surface charge, but populations were heterogeneous.
- Activated macrophages had lower zeta potential and higher isoelectric points.
- Activated macrophages showed increased surface sialic acid residues sensitive to Clostridium perfringens neuraminidase.
Conclusions:
- Macrophage surface charge is heterogeneous and influenced by activation state.
- Sialic acid residues contribute significantly to the surface charge, especially in activated macrophages.
- Calcium ions may bind to anionic sites on the macrophage surface, affecting EPM.