Cytological basis for enhancement of radiation-induced mortality by Friend leukaemia virus infection

Purpose : To analyse the cytological basis for enhancement of radiation-induced mortality by Friend leukaemia virus infection. Materials and methods : Cellularity in haematopoietic tissues of C3H mice infected with FLV and/or whole-body irradiation was examined. Results : When mice were treated with a sublethal dose (3 Gy) of irradiation at 1 week after virus infection, most manifested a severe loss of cellularity in the spleen, bone marrow and peripheral blood 2 weeks after irradiation. More than 90% of the mice died within 1 month post-irradiation. However, this deleterious effect of virus infection on the survival of irradiated mice was observed only when they were irradiated at around 1 week after virus inoculation. Strain differences in the sensitivity to this effect were observed among virus-sensitive strains of mice. Conclusions : The results indicate that Friend leukaemia virus infection can cause enhancement of radiation sensitivity of haematopoietic cells in host animals in a restricted manner in terms of genetic background and the interval between infection and irradiation.