Flow-cytometric analysis of recipient leukocyte replacement in radiation bone marrow chimeras. The replacement of various leukocyte populations in B6.CD45.2 mice was analyzed 4 weeks after 10-Gy radiation and congenic bone marrow transplantation from B6.CD45.1 bone marrow donors. (A) Approximately 90% of intrahepatic leukocytes were replaced by donor-type leukocytes. The remaining 10% were almost entirely TCR-positive (top left) and negative for CD45R/B220, CD11b, and MHC class II, indicating that they were non-Kupffer cells. (B) The origin of isolated intrahepatic macrophages was greater than 99% donor BM-derived, based on expression of CD11b and MHC class II (IA^b). Numbers on plots are percentages of lymphocytes.