Keywords: optimum adapting dose, adaptive response, ionising radiation, human lymphocytes, chromosome aberrations, low radiation, optimum irradiation time
The search for a possible optimum adapting dose under the optimum irradiation time scheme in cultured human lymphocytes
One of the most important questions in adaptive response studies is still the possible existence of an optimum adapting dose. In this study, using the optimum irradiation time scheme (24–48) that was reported by other investigators, we monitored the cytogenetic endpoint of chromosome aberrations to assess the magnitude of adaptation to ionising radiation in the cultured human lymphocytes. Lymphocytes were pre-exposed to an adapting dose of 1–20 cGy at 24 hours, before exposure to an acute challenge dose of 1 or 2 Gy at 48 hours. Cells were fixed at 54 hours. Lymphocytes, which were pretreated with 5 or 10 cGy adapting doses, had significantly fewer chromosome aberrations. In spite of the fact that lymphocytes of some of our blood donors which were pre-treated with 1 or 20 cGy adapting doses, showed an adaptive response, the pooled data (all donors) indicated these two adapting doses cannot induce a significant adaptive response.