FCs persist in allogeneic animals after transplantation. C3H mice were conditioned with 950 cGy TBI and received transplants of 5000 KSL HSCs with or without 30 000 EGFP⁺ FCs. Mice were killed at 2 and 4 weeks, and EGFP⁺ FCs (CD8⁺/TCR^-) were enumerated in spleen, peripheral blood (PB), and bone marrow. A minimum of 1 × 10⁶ events was analyzed. % reflects percent of GFP⁺ FCs in lymphoid gate. A minimum of 3 mice were analyzed per time point.