Age-related increase of protein glycation in peripheral blood lymphocytes is restricted to preferential target proteins.

Advanced glycation end products (AGE) have been analyzed in aging human peripheral blood lymphocytes since protein glycation and glycoxidation are believed to contribute to the intracellular age-related accumulation of damaged proteins, a process that has been associated with the cellular functional deficits that occur with age. The appearance of AGE in cell lysates was monitored with an enzyme-linked immunosorbent assay using an anti-AGE antibody raised against glycated RNAse. When lymphocyte cytosolic extracts from old donors (86-91 years old) were compared with those from young donors (20-25 years old), a small but significant 40% increase of protein glycation was observed. In both age groups, further analysis of the pattern of glycated proteins by two-dimensional gel electrophoresis followed by western blotting with the same anti-AGE antibody, showed that the protein silver stain and the immunoblot patterns were not superimposable indicating that glycoxidative modifications are targeting only a restricted set of proteins. Among these preferential protein targets, seven of them exhibited a significant age-related increased immunoreactivity with the anti-AGE antibody suggesting that the corresponding modified proteins might serve as biomarkers of aging lymphocytes.