[Changes in the function of lymphocyte blast formation with aging estimated by ethidium bromide fluorescence assay]

Modification of DNA with aging has been proposed as a mechanism of cellular senescence. To test this hypothesis, we measured fluorescence of the DNA-Ethidium bromide (EB) complex in human peripheral lymphocytes. Lymphocytes were incubated in a medium containing phytohemagglutinin (PHA-P). EB was linked to lymphoblast-DNA. Healthy adults of three age groups were examined: 40-49 (N = 14), 50-59 (N = 16), 60-69 (N = 8). Moreover, we studied lymphocytes from 17 patients (47-74 years old) with probable Alzheimer's disease. An aged-related linear decrease in fluorescence intensity was found in healthy controls (r = 0.135, p < 0.05), and for Alzheimer's disease patients (r = 0.443, P < 0.10). The regression equation are: Y = -0.0405X + 7.164 (Healthy Controls) Y = -0.121X + 11.258 (Alzheimer's disease patients) where X and Y are age and fluorescence, respectively. These results indicate that the analysis of DNA-EB fluorescence in lymphocytes may be useful in the study of changes associated with aging, and also in the evaluation of the clinical diagnosis of Alzheimer's disease.