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Published on: March 7, 2019
Macrophage recognition of the erythrocytes modified by oxidizing agents
Abstract:
Mouse erythrocytes modified by oxidizing agents (ADP/Fe3+, tert-butyl hydroperoxide and phenylhydrazine) were examined for recognition by autologous macrophages (cell adhesion and phagocytosis). Treatment of erythrocytes with ADP/Fe3+ resulted in lipid oxidation but no significant alterations in physical properties, and the treated cells were adherent to macrophages. When the lipid oxidation of erythrocytes was prevented by alpha-tocopherol, erythrocytes were not susceptible to macrophage adhesion, indicating that free radical reactions involving lipid oxidation are responsible for the formation or exposure of the membrane sites for the macrophage adhesion. Treatment of erythrocytes with tert-butyl hydroperoxide caused lipid oxidation and alterations in physical properties. Deformability and osmotic fragility of the treated cells were markedly low. Not only cell adhesion but subsequent phagocytosis of the treated cells by macrophages were observed. A similar effect was observed on treatment of erythrocytes with phenylhydrazine. The pronounced alterations in physical properties of the erythrocytes treated with tert-butyl hydroperoxide and phenylhydrazine may be responsible for the macrophage phagocytosis.
Insights
Oxidizing agents trigger erythrocyte (red blood cell) lipid oxidation, leading to macrophage adhesion. Significant physical changes in red blood cells enhance their phagocytosis by macrophages.
Area of Science:
- Immunology
- Cell Biology
- Hematology
Background:
- Macrophages are key immune cells involved in clearing aged or damaged cells.
- Erythrocyte (red blood cell) surface modifications can influence their recognition by macrophages.
- Oxidative stress is implicated in cellular damage and immune responses.
Purpose of the Study:
- To investigate the role of erythrocyte lipid oxidation in macrophage recognition.
- To determine the impact of altered erythrocyte physical properties on phagocytosis.
- To elucidate the mechanisms by which oxidizing agents affect erythrocyte-macrophage interactions.
Main Methods:
- Treatment of mouse erythrocytes with oxidizing agents: ADP/Fe3+, tert-butyl hydroperoxide, and phenylhydrazine.
- Assessment of lipid oxidation and physical properties (deformability, osmotic fragility) of treated erythrocytes.
- Evaluation of erythrocyte adhesion and phagocytosis by autologous macrophages in vitro.
Main Results:
- ADP/Fe3+ treatment induced erythrocyte lipid oxidation, promoting macrophage adhesion, which was blocked by alpha-tocopherol.
- Tert-butyl hydroperoxide and phenylhydrazine caused significant lipid oxidation and reduced erythrocyte deformability and osmotic fragility.
- Erythrocytes treated with tert-butyl hydroperoxide and phenylhydrazine exhibited both adhesion and subsequent phagocytosis by macrophages.
Conclusions:
- Free radical-mediated lipid oxidation is crucial for generating macrophage adhesion sites on erythrocytes.
- Marked alterations in erythrocyte physical properties, induced by certain oxidizing agents, enhance macrophage phagocytosis.
- Oxidative stress plays a significant role in the clearance of erythrocytes by the immune system.
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