Involvement of sialylated poly-N-acetyllactosaminyl sugar chains of band 3 glycoprotein on senescent erythrocytes in anti-band 3 autoantibody binding.

When young and senescent erythrocytes, separated from freshly collected human blood, were incubated with 125I-goat anti-human IgG, binding of the IgG to the senescent cells was three times as high as that to the young cells. The release of the radioactivity from the anti-human IgG-bound senescent cells was enhanced by incubation with band 3 oligosaccharides but not by those digested with endo-beta-galactosidase or neuraminidase. The senescent cells whose surface band 3 saccharide chains were cleaved by endo-beta-galactosidase or totally removed by N-glycosidase F showed decreased binding of the anti-human IgG. The radioactivity was effectively released from the anti-human IgG-bound senescent cells by digestion with endo-beta-galactosidase. The results suggest that senescent erythrocytes bind anti-band 3 autoantibody, and the antigenic sites on the cell surface are sialylated poly-N-acetyllactosaminyl sugar chains of band 3 glycoprotein.