Age population distribution of erythrocytes in young and old healthy donors.

Reports from several laboratories on a shorter life span of erythrocytes (E) in old animals and humans, induced the authors to search for a simple method for determining the younger age distribution of E in the blood of 20 old (over 70), as compared to 20 young (below 40), healthy donors. The following tests were performed: 1) Density Distribution of Cells (DDC), 2) Osmotic Fragility, 3) Agglutinability of E by Poly-L-lysine, 4) Analysis of Aspartate Amino Transferase (AST) activity, 5) Test for the presence of immunoglobulin on the surface of E (rosette formation on K562 cells); and 6) All the usual clinical and hematological tests were performed in order to avoid pathology. The most significant difference between the blood of the young and the old was found in the DDC. The shift of the cumulative curve indicated a younger population of cells in the blood of the elderly. The activity of AST was higher in the blood of the elderly, also indicating a younger cell population. The rosette formation was higher with the E from the blood of the elderly, indicating that the E, had more immunoglobulins on their surface than the E from the blood of the younger donors.