Cellular dehydration and immunoglobulin binding in senescent neonatal erythrocytes

The life span of neonatal erythrocytes (60-80 days) is shorter than that of adult erythrocytes (120 days). We studied neonatal red blood cells separated on stractan density gradients to further characterize the aging process and to explore the possibility that senescence antigens play a role in the destruction of neonatal erythrocytes. Quantitation of membrane proteins 4.1a and 4.1b served as a marker for cell age and confirmed an enrichment for senescent red cells in the most dense layers of the gradients. Despite the shorter life span of neonatal erythrocytes, cord blood contained a larger percentage of very dense, K+-depleted red cells than did adult blood. ATP levels in dense neonatal and adult cells were decreased to 50-80% of normal values for unseparated red cells. Levels of reduced glutathione did not fall with increasing cell density. Sodium dodecyl sulfate polyacrylamide gel electrophoresis of red cell membrane proteins showed increased membrane-associated globin in senescent neonatal cells, but such gels run without reducing agents did not show oxidative protein cross-linking. Membrane bound immunoglobulins were detected on senescent neonatal and adult red cells by the rosetting antiglobulin test. We conclude that senescence antigens are revealed during the aging process of neonatal erythrocytes, thereby labeling them for antibody-mediated destruction in the reticuloendothelial system.