Macrophage recognition of the erythrocytes modified by oxidizing agents.

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.