Comparison on the direct and bystander effect in lymphocyte and fibroblast exposed to low and high linear energy transfer radiation and to calculate its relative biological effectivenes

Abstract

It is important to understand the significance of alpha particle induced bystander effects newlineRIBE radiation induced genomic instability RIGI and its relative biological effectiveness this is because the phenomenon is not universal and the mechanism is unclear and the RBE is widely varying and projected to be very high Isolated lymphocytes from healthy volunteers were exposed to either low influence alpha particles gamma rays or X rays 225 kVp and 6 MV and Human Adult Dermal Fibroblast HADF was exposed to alpha and gammarays Co culture methodology using Thincert was employed to investigate bystander effects BE Chromosomal aberrations and micronucleus formation were used to study the RIBE RIGI and to calculate RBE Lymphocytes directly exposed to the different types of radiation showed a dose dependent increase in the frequency of CA and MN dose independent increases in the frequency of these chromosomal damages in co cultured bystander cells implies that all three types of radiation induced a BE The calculated RBE at the level of 5 percent induced aberrations varied between 9 to 20 for direct and in bystander population RIGI inlymphocytes and HADF exposed to alpha particles remains significantly less than 0 point 002 higher when compared to X rays The radiation induced secondary bystander response RISBE was also studied and their persistence was longer in alpha particle irradiated cells The magnitude of low fluence alpha particle induced RIBE is higher than in low LET linear energy transfer radiation The RBE also varies depending upon the endpoints used and adds up to targeted effects Since the endpoint of CA is considered as important and early marker to estimate observed dose in radiation biodosimetry the RIBE RIGI and RBE using CA as a marker are relevant for radiation protection purposes Moreover the novelty in this study is that the CA in bystander cells are taken into account and RBE is calculated RIGI studied in both direct, and bystander population and the results shows the primary bystander cells in turn p