OXIDATIVELY DAMAGED ERYTHROCYTES ARE RECOGNIZED BY MEMBRANE-PROTEINS OF MACROPHAGES

Human erythrocytes incubated with an iron catalyst ADP-chelated Fe3+ u ndergo oxidative damage of the membrane including lipid peroxidation, protein oxidation, and protein aggregation, and become susceptible to recognition by human macrophages. Ln order to clarify the membrane com ponents 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 bind ing was effectively inhibited by saccharide chains of band 3, a major glycoprotein of human erythrocytes, and lowered when the saccharide ch ains of band 3 were removed from the cell surface by pretreatment of t he cells with endo-beta-galactosidase which specifically cleaves the p olylactosaminyl 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 oxida tively damaged erythrocytes are specifically recognized by these prote ins of macrophage membrane having saccharide binding ability.