Antigenic determinants of senescent antigen of human erythrocytes are located in sialylated carbohydrate chains of Band 3 glycoprotein.
Naturally occurring IgG autoantibody against Band 3 glycoprotein of human erythrocyte membrane (anti-Band 3) recognizes the erythrocytes modified with oxidizing or SH-blocking agents as well as senescent erythrocytes. Location of the antigenic determinants of Band 3 this autoantibody recognizes was investigated by competitive inhibition studies of the antibody binding to the modified cells. Autologous IgG binds to the modified erythrocytes, and purified Band 3 totally inhibits the binding. This inhibitory activity of Band 3 was not affected by digestion of Band 3 with various proteases. Treatment of Band 3 with endo-beta-galactosidase that destroys the poly-N-acetyllactosaminyl sugar chain of Band 3 or with neuraminidase resulted in loss of the inhibitory activity. Oligosaccharides released from Band 3 by hydrazinolysis effectively inhibited the binding of autologous IgG and 125I-labeled purified anti-Band 3 to the modified cells, whereas the oligosaccharides depleted of acidic components did not. Endo-beta-galactosidase and neuraminidase destroyed the activity of the oligosaccharides, but alpha-L-fucosidase did not. Furthermore, human lactoferrin that contains sialylated two N-acetyllactosaminyl units also exhibited potent inhibitory activity, and the activity was destroyed by endo-beta-galactosidase and neuraminidase. These results indicate that the antigenic determinants of Band 3 are located in sialylated poly-N-acetyllactosaminyl sugar chains. Based on this finding, mechanism of appearance of the antigen on senescent erythrocytes recognized by anti-Band 3 (senescent antigen) was discussed.
Beppu
M
M
Tokyo College of Pharmacy, Japan.
Mizukami
A
A
Ando
K
K
Kikugawa
K
K
D001457:Anion Exchange Protein 1, Erythrocyte / Q000737:chemistry / Q000276:immunology*; D001323:Autoantibodies / Q000276:immunology*; D002240:Carbohydrate Sequence; D002241:Carbohydrates / Q000276:immunology*; D003958:Diamide / Q000494:pharmacology; D010450:Endopeptidases; D000939:Epitopes / Q000032:analysis*; D004905:Erythrocyte Aging; D004912:Erythrocytes / Q000276:immunology*; D005033:Ethylmaleimide / Q000494:pharmacology; D006026:Glycoside Hydrolases; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology; D008562:Membrane Glycoproteins / Q000737:chemistry* / Q000276:immunology; D008969:Molecular Sequence Data
D001457:Anion Exchange Protein 1, Erythrocyte; D001323:Autoantibodies; D002241:Carbohydrates; D000939:Epitopes; D007074:Immunoglobulin G; D008562:Membrane Glycoproteins; D003958:Diamide; D006026:Glycoside Hydrolases; D010450:Endopeptidases; D005033:Ethylmaleimide