An investigation of DNA excision repair capacity in human CD4+ T cell clones as a function of age in vitro.

DNA damage has been shown to increase with age in lymphocytes of healthy humans and in human CD4+ T cell clones. Such genetic damage, if unrepaired, may have a detrimental effect on lymphocyte-mediated immune responses. This study investigated DNA excision repair capacity of human CD4+ T cell clones as a function of age in vitro. Cultures of T cell clones were treated with a range of DNA damaging agents; hydrogen peroxide, N-methyl-N'-nitro-N-nitrosoguanidine or 254 nm ultraviolet irradiation. Following treatment, the amount of DNA damage in the clones was determined over a time course using modified comet assays. The results obtained revealed a decline related to in vitro age in the DNA repair capacity of clones derived from a 26 and a 45 year old donor. This decline may represent at least a partial explanation for the age related increase in DNA damage in these clones when cultured in vitro. In contrast, there was no evidence for a decline related to in vitro age in repair capacity in the clones derived from an 80 year old SENIEUR donor. An alternative mechanism must underlie the age related increased in DNA damage in these clones when cultured in vitro.