Effect of mediastinal irradiation on donor chimerism in peripheral blood in an Ly5-congenic strain combination. CD45.1 congenic B6 mice received 200 × 10⁶ B6 BMCs and either no MI (; n = 7) or 7-Gy MI (▦; n = 5). Mean percentages of donor CD4 cells, CD8 cells, B cells, monocytes, and granulocytes in WBCs are shown at the indicated time points. Statistically significant differences in chimerism in all lineages was seen between the no MI group and the 7-Gy MI group at all time points (except the CD4 cell lineage at 2 weeks). Error bars indicate SD.