Radioadaptive Response in Human Lymphocyte Cells

The adaptive response (AR) is a phenomenon by which cells exposure to sublethal doses of DNA-damaging
agents (non-mutagenic dose of chemical or radiation), known as conditioning treatment (CT), leads to increased
resistance to a subsequent exposure to a higher dose of the same or other agents, known as challenge treatment
(CR). The adaptive response (AR) induced by radiation in human lymphocytes has been reported in a range of 1-
20cGy pre-exposure. In this study, we investigated the adaptive response using 5cGy conditioning dose of
gamma rays followed by 2 Gy challenging dose in peripheral human lymphocyte cells. Blood samples were
taken from 30 female volunteers and this experiment was carried out by delivering 5 cGy gamma radiation
followed by 2 Gy of challenging. Consequently, the number of micronuclei (MN) in binuclear lymphocyte cells
was counted as an endpoint. The results showed that the mean frequency of micronuclei in binuclear
lymphocytes which have received both conditioning and challenge doses are significantly reduced in comparison
to those only exposed to 2 Gy (20.46±2.13, 30.2±3.29) (P< 0.01). The results showed the existence of an in vitro
adaptive response in lymphocyte cell exposed to low dose of gamma radiations.