The Radiosensitivity of the Processes of DNA-synthesis in Mouse Spleen

Abstract

The effect of different doses of X-rays on DNA-synthesis in mouse-spleen lymphocytes during the synthetic period has been studied in vivo and in vitro. DNA-synthesis was measured by the incorporation of 3H- or 14C-thymidine. The data have confirmed that the radiosensitivity is markedly greater in vivo. The discrepancy was not readily remedied by fortification of the incubation medium by "energy-producing" substances, and the increased depression does not seem to be due to the release of DNA-metabolites or an inhibitor of DNA-synthesis by the intact spleen. A triphasic response for lymphocytes in vivo is postulated to explain the greater radiosensitivity.