Inflammatory BM-derived KCs were not directly recruited from the bone marrow. (A) Bone marrow chimeras were injected with fluorescent microspheres and then infected with influenza. Microspheres were immediately removed from the circulation by phagocytes, but focus formation within the livers did not occur until 5 days after infection. The accumulation of bead-carrying KCs indicated that KCs engaging in focus formation had already populated the liver several days earlier and were not derived from circulating monocytes. KCs (F4/80-Cy5) are displayed in false color blue, DAPI-stained nuclei are red, and fluorescent microspheres green. (B) To evaluate if the sessile KC population was derived from radioresistant intrahepatic precursor cells, hepatic KCs were entirely eliminated by clodronate liposome injection 3 weeks after bone marrow transplantation. Three weeks or 9 weeks later, sections from bone marrow chimeras were stained for BM-derived (CD45.1, blue) and sessile (CD45.2, green) KCs (F4/80, red). While recipient CD45.2 non-KC leukocytes (lymphocytes, granulocytes, etc) were abundant 3 and 9 weeks after clodronate injection, there were only BM-derived KCs in the liver sections of these animals; sessile KCs were not detectable. Original magnification, ×400.