Comparison of UV-induced unscheduled DNA synthesis in lymphocytes exposed to low doses of ionising radiation in vivo and in vitro

In an attempt to understand and ascertain the stimulatory effects of low-do se ionising radiation, a study was conducted to compare the changes in the UV-induced repair capacity of human blood cells exposed to low conditioning doses of ionising radiation under in vivo and in vitro conditions. ii sign ificant increase in the rate of UV induced Unscheduled DNA synthesis (UDS) in lymphocytes pre-exposed to low doses of ionising radiation was observed both under in vitro and in vivo conditions. There was also a significant co rrelation between the adapting dose and net UDS in lymphocytes of radiation workers implying that the triggering action of the adaptation process is d ose dependent. However, on comparing the extent of UV-induced UDS of the in vivo and in vitro exposures, significantly higher rates of UDS were observ ed in the lymphocytes of radiation workers when compared to a corresponding in vitro adapting dose. We postulate that the response in vivo is much mor e pronounced due to cell repopulating events and extra cellular secretory f actors like hormones etc,. (C) 2000 Elsevier Science B.V. All rights reserv ed.