Radiation-induced DNA damage and repair in human gammadelta and alphabeta T-lymphocytes analysed by the alkaline comet assay.

It has been shown by a number of authors that the radiosensitivity of peripheral blood mononuclear cells (PBMC) is higher in cancer patients compared to healthy donors, which is interpreted as a sign of genomic instability. PBMC are composed of different cell subpopulations which are differently radiosensitive and the difference between cancer patients and healthy donors could also be due to different composition of their PBMC pools. Gamma-delta T-lymphocytes play an important role in immunosurveillance and are promising cells for immunotherapy. Their abundance is frequently reduced in cancer patients so should their sensitivity to radiation be lower than that of other T-lymphocytes, this could, at least partly explain the low radiosensitivity of PBMC from healthy individuals compared to cancer patients. The present investigation was carried out to test this. Using the alkaline comet assay we analysed the level of DNA damage and repair in isolated gammadelta T-lymphocytes, pan T-lymphocytes and in total PBMC exposed in vitro to gamma radiation. We found no difference in the level of DNA damage and the capacity of DNA repair between the T cell populations. This is the first study that addresses the question of sensitivity to radiation of gamma-delta T-cells.