抄録
The current challenge of radiation biology research is to carefully define the response of cells and tissues to low dose exposure. With the observation of non-targeted responses, where cells do not respond according to the classical model of direct DNA damage, the response at low dose may not follow the predictions of the linear no threshold model. Our own approach has been to develop both charged particle and X-ray microbeams to accurately probe the spatial and low dose dependencies of cellular and tissue response. Our emphasis has been on the bystander response where cells, which have not been directly irradiated respond to their neighbours being exposed. These have been observed in a range of cell types under conditions where even exposure of only a single cell can lead to triggering of a bystander response. A common feature is that the responses predominate at low doses and saturate at higher exposure levels. Many factors have been shown to play a role in the downstream response. From our own studies we suggest that the release of the signal is a fundamental process which may not be related to the phenotype of the cell being targeted. However the ability of a population to respond to the released bystander signal is highly cell phenotype dependent, with cell type, cell cycle phase and DNA repair capacity all playing a modulating role.
