Abstract
Previously, we examined early events for lymphoma development in C57BL/6 mice after four consecutive irradiations of 1.8 Gy γ-rays at 1-week intervals, and it is concluded that the early stage of lymphomagenesis, induction of DNA double strand breaks, aneuploidy, delayed chromosomal instability, appearance of reactive oxygen (ROS) producing T cells, bystander effects, arrangements of cancer-related genes, and cell clonality were observed. Induction of these abnormalities might be associated with radiation-induced thymocyte atrophy. For a detailed analysis of early events of lymphomagenesis, the prelymphoma marker might be a useful tool. The thymic prelymphoma cells in sprit-dose irradiated B10 mice have been characterized phenotypically in relation to expression the marker defined by the mAb against TL-2 (thymus-leukemia) antigen. However in B6 mice, the expression of TL-2 antigens was limited. We found an monoclonal antibody against Ly-6C, which reacted at early stage of prelymphomas in irradiated B6 mice more strongly than TL-2. Also, Ly-6C positive cells were shown to be ROS-producing cells among the irradiated thymuses. Using an intrathymic infection assay after 4-10weeks of irradiation, it was demonstrated that some part of thymic lymphomas developed from cells highly reacted with anti Ly-6C antibody. It is concluded that Ly-6C surface antigen can be used as a marker of radiation-induced thymic prelymphomas.
