Radioprotective effect of H2K-BCL-2 for hematopoietic populations following irradiation. (A) Cellularity in bone marrow, spleen, and thymus of H2K-BCL-2 transgenic mice and wild-type littermates following split-dose, 9.5-Gy total body irradiation. Bold lines, filled symbols depict H2K-BCL-2, thin lines; open symbols wild-type littermates. Circles show data from founderline 1043, rectangles from founderline 1053. Each datapoint represents one to three mice, the results from two separate experiments (circles and rectangles) are shown. (B) Flow cytometric analysis of bone marrow, thymus and spleen of H2K-BCL-2/1043 transgenic mice and wild-type littermates before (day 0) and after split-dose, 9.5-Gy total body irradiation. (Top left) B cells in bone marrow 16 hours after irradiation. This illustrates the extreme radiosensitivity of wild-type B cells. (Top right) Myeloid cells at the same timepoint. These relatively radioresistant cells accumulate in wild-type mice. (Bottom left) CD4 and CD8 staining in spleen 6 and 9 days after irradiation, illustrating the relative radiosensitivity of CD8 cells in wild-type mice. (Bottom right) CD4 and CD8 populations in thymus 6 and 9 days after irradiation. (C) Fate of various hematopoietic populations after irradiation. Symbols as in (A). The top two plots show erythroid cells in bone marrow (left) and myeloid cells in spleen (right). The second row shows NK cells (left) and B cells (right) in spleen. All as percentage of the populations before irradiation.