Non myeloablative conditioning and co-stimulatory blockade for chimerism induction. (A) C3H/Hen recipient mice were conditioned with busulfan (2×30mg/Kg) and T cell debulking (TCD) with 300mg anti CD4 and anti CD8. Post transplant treatment included 200mg CTLA4 Ig, 250mg anti CD48, and 0.1mg FTY720 administered at the indicated time points. (B-C): Long term multilineage chimerism (A) Chimerism level 163 days after cessation of immune suppression. (B) Typical multilineage chimerism in the spleen of a chimeric mouse shown in B.