Age related change in the frequency of ara C-induced chromosome aberrations in human peripheral blood lymphocytes

1-beta-D-Arabinofuranosylcytosine (ara C) has been known to inhibit repair replication in the G1 phase of cell cycle and to convert certain types of DNA damage into chromosome-type exchanges: e.g., dicentric or ring chromosomes. It is then considered to be a useful cytogenetic method to investigate the frequency of ara C-induced dicentric and ring chromosomes (dic and ring) for estimating cellular DNA damage or capacity to repair it. Peripheral blood lymphocytes from donors ranging from newborn to 91 years old were treated with 10 microM ara C in their G1 phase and the resulting disc and ring were observed to investigate whether age-related change in peripheral lymphocytes would be present in the amount of spontaneous DNA damage or in the capacity to repair it. Chromatid-type (Ct) aberrations and sister chromatid exchanges (SCEs) were also scored for additional cytogenetic indices of DNA damage in the lymphocytes. The results showed that the frequency of dic and ring had a negatively linear correlation with the logarithm of the age of the blood donors, but that the frequencies of Ct aberrations and SCEs were not influenced by the age. The present study suggests the presence of age-related change in the amount or in the capacity to repair certain types of DNA damage in the G1 phase of human peripheral lymphocytes. Other possible explanations for the present results are also discussed.