Host: The Japan Radiation Research Society
Co-host: City of Kitakyushu, University of Occupational and Environmental Health, Japan
It is known that lymphoid tumors develop in nonirradiated syngeneic thymic grafts implanted into thymectomized, irradiated mice. This indirect effect of radiation on the induction of lymphomas indicates one of the mechanisms for radiation-induced lymphomagenesis. DNA-PK-deficient mutant (scid) mice were thymectomized, either nonirradiated or irradiated with 0.1 Gy to 1 Gy, and then transplanted with thymuses from new born B6-GFP mice subcutanesouly or under the kidney capsules. 100 to 200 days after implantation, T-cell lymphoma of graft origin developed with the incidence of 4-7% at 0 Gy to 19-30% at 1 Gy, and the differences in the indirect effect on the induction of T-cell lymphomas was substantiated in scid mice at 1 Gy. Bone marrow transplantation from B6 mice into irradiated, thymectomized scid mice prevented T-cell lymphoma development, suggesting that the indirect effect might be caused by severely restricted repopulation of grafted thymus, which might increase genetic and epigenetic plasticity during forced proliferation of cells.
