Membrane proteins of human erythrocytes are modified by advanced glycationend products during aging in the circulation

Recent immunological studies demonstrated that proteins in vivo in several diseases are subjected to post-translational modification by advanced glyca tion end products (AGrEs), suggesting a potential role of AGEs in aging and age-enhanced disease processes such as diabetic complications, atheroscler osis and Alzheimer's disease. N-epsilon-(Carboxymethyl)lysine (CML) is one of the major AGE-structures demonstrated in vivo so far. In the present stu dy, membrane proteins from young erythrocyte population mere compared with those from senescent erythrocytes separated from the same individual in the ir CML-contents using a monoclonal antibody for CML (6D12). SDS-polyacrylam ide gel electrophoresis and subsequent Western blot showed that 6D12 bound to the band 1, 2, 3, 4.2, 5, 6 and 7 proteins from senescent erythrocytes, but not to those from young erythrocyte. Furthermore, quantitative estimati on of the reactivity of 6D12 to these erythrocyte membranes by ELISA showed that the reactivity of 6D12 to senescent erythrocyte membranes was 3- to 6 -fold higher than that of young erythrocyte membranes. These results indica te that membrane proteins of circulating erythrocytes undergo CML-modificat ion, and the modified proteins accumulated in an age-dependent manner durin g the life span of erythrocytes. (C) 1999 Academic Press.