Chromosomal damage and ageing: effect on micronuclei frequency in peripheral blood lymphocytes

Background: instability in the organization and expression of the genetic m aterial has been hypothesized as the basic mechanism of ageing. Objective: to quantify the effect of ageing on chromosomal damage as measur ed by spontaneous micronuclei (MN) frequency in peripheral blood lymphocyte s. Method: analysis of a large population sample from two laboratories applyin g the cytokinesis-block technique and a third using traditional interphase analysis. The age-related effect on baseline level of micronuclei frequency and on cell proliferation measures was further investigated in a study of peripheral blood samples from healthy subjects. Results: there was an increase of MN frequency with age. The regression lin es showed a positive slope and were statistically significant (P < 0.01) wi th a steeper trend for cytochalasin B-treated samples. An inverse correlati on with age was detected for the percentage of binucleated cells in laborat ories using cytochalasin B. This study confirms the increase of basal level of MN with age. A decrease by age in proliferation efficiency measured by the percentage of binucleated cells suggests an interference of age-related factors on cell division. Conclusion: there is an increase in MN frequency with increasing age.