Related Experiment Videos
Oxidatively damaged erythrocytes are recognized by membrane proteins of macrophages
1School of Pharmacy, Tokyo University of Pharmacy and Life Science, Japan.
Abstract:
Human erythrocytes incubated with an iron catalyst ADP-chelated Fe3+ undergo oxidative damage of the membrane including lipid peroxidation, protein oxidation, and protein aggregation, and become susceptible to recognition by human macrophages. In order to clarify the membrane components of macrophages responsible for the recognition of the oxidized erythrocytes, binding of the oxidized cells to dot and Western blots of solubilized membrane of macrophages was investigated. The oxidized erythrocytes but not unoxidized cells bound to the dot blots. The binding was effectively inhibited by saccharide chains of band 3, a major glycoprotein of human erythrocytes, and lowered when the saccharide chains of band 3 were removed from the cell surface by pretreatment of the cells with endo-beta-galactosidase which specifically cleaves the polylactosaminyl saccharide chains of band 3. The oxidized erythrocytes bound to the membrane proteins of macrophages with molecular mass of about 50, 80, and 120 kDa on Western blots depending on the saccharide chains of band 3 on their surface. The results suggest that the oxidatively damaged erythrocytes are specifically recognized by these proteins of macrophage membrane having saccharide binding ability.
Insights
Oxidatively damaged red blood cells (erythrocytes) are recognized by macrophages. This recognition involves specific macrophage membrane proteins binding to saccharide chains on damaged erythrocytes.
Area of Science:
- Cell biology
- Immunology
- Biochemistry
Background:
- Oxidative damage to human erythrocytes alters their membrane properties.
- These altered erythrocytes become susceptible to recognition by macrophages, a key component of the immune system.
Purpose of the Study:
- To identify specific macrophage membrane components responsible for recognizing oxidatively damaged erythrocytes.
- To elucidate the role of erythrocyte membrane components in this recognition process.
Main Methods:
- Incubation of human erythrocytes with an iron catalyst (ADP-chelated Fe3+) to induce oxidative damage.
- Binding assays using dot and Western blots with solubilized macrophage membranes.
- Inhibition studies using saccharide chains of band 3 and enzymatic removal of these chains.
Main Results:
- Oxidized erythrocytes, but not unoxidized cells, bound to macrophage membrane components.
- Binding was inhibited by saccharide chains of band 3, a major erythrocyte glycoprotein.
- Binding was reduced when these saccharide chains were removed enzymatically.
- Western blots revealed oxidized erythrocytes bind to macrophage proteins of approximately 50, 80, and 120 kDa.
Conclusions:
- Macrophage membrane proteins with molecular masses of 50, 80, and 120 kDa are involved in recognizing oxidatively damaged erythrocytes.
- The saccharide chains of band 3 on the erythrocyte surface play a crucial role in this specific recognition.
- These findings suggest macrophage proteins with saccharide-binding capabilities mediate the recognition of damaged erythrocytes.